Re: [PATCH 6/7] smp: Don't yell about IRQs disabled in kgdb_roundup_cpus()

2018-10-30 Thread Peter Zijlstra 
On Mon, Oct 29, 2018 at 11:07:06AM -0700, Douglas Anderson wrote:
> In kgdb_roundup_cpus() we've got code that looks like:
>   local_irq_enable();
>   smp_call_function(kgdb_call_nmi_hook, NULL, 0);
>   local_irq_disable();

> Let's add kgdb to the list of reasons not to warn in
> smp_call_function_many().  That will allow us (in a future patch) to
> stop calling local_irq_enable() which will get rid of the original
> splat.
> 
> NOTE: with this change comes the obvious question: will we start
> deadlocking more often now when we drop into the debugger.  I can't
> say that for sure one way or the other, but the fact that we do the
> same logic for "oops_in_progress" makes me feel like it shouldn't
> happen too often.  Also note that the old logic of turning on
> interrupts temporarily wasn't exactly safe since (I presume) that
> could have violated spin_lock_irqsave() semantics and ended up with a
> deadlock of its own.

How is any of that not utterly and terminally broken?

> @@ -413,7 +414,8 @@ void smp_call_function_many(const struct cpumask *mask,
>* can't happen.
>*/
>   WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
> -  && !oops_in_progress && !early_boot_irqs_disabled);
> +  && !oops_in_progress && !early_boot_irqs_disabled
> +  && !in_dbg_master());
>  
>   /* Try to fastpath.  So, what's a CPU they want? Ignoring this one. */
>   cpu = cpumask_first_and(mask, cpu_online_mask);

Not a fan of this. There is a distinct difference between
oops_in_progress and dropping into kgdb in that you don't ever expect to
return/survive oopses, whereas we do expect to survive kgdb.

Also, how does kgdb work at all without actual NMIs ?

So no, NAK on this.

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Re: [PATCH 0/7] serial: Finish kgdb on qcom_geni; fix many lockdep splats w/ kgdb

2018-10-30 Thread Russell King - ARM Linux 
On Tue, Oct 30, 2018 at 11:56:28AM +, Daniel Thompson wrote:
> On Mon, Oct 29, 2018 at 11:07:00AM -0700, Douglas Anderson wrote:
> > Looking back, this is pretty much two series squashed that could be
> > treated indepdently.  The first is a serial series and the second is a
> > kgdb series.
> 
> Indeed.
> 
> I couldn't work out the link between the first 5 patches and the last 2
> until I read this...
> 
> Is anything in the 01->05 patch set even related to kgdb? From the stack
> traces it looks to me like the lock dep warning would trigger for any
> sysrq. I think separating into two threads for v2 would be sensible.

I'm concerned about calling smp_call_function() from IRQ context with
IRQs disabled - that will block the ability of the _calling_ CPU to
process IPIs from other CPUs in the system.  If we have other CPUs
waiting on their IPIs to complete on _this_ CPU, we could end up
deadlocking while trying to grab the CSD lock.

This is the intention of warnings in smp_call_function*() - to catch
cases where deadlocks _can_ occur, but do not reliably show up.

The exceptions to the warning (disregarding oops_in_progress) are
chosen to allow IRQs-disabled calls when we're sure that the rest of
the system isn't going to be sending the calling CPU an IPI (eg,
because the CPU isn't marked online, and we only send IPIs to online
CPUs, or if we're still early in the kernel boot and hence have no
other CPUs running.)  The exception is oops_in_progress, which can
occur at any time - even with the current CPU already holding some
CSD locks (eg, oops while trying to send an IPI.)

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Re: [PATCH 7/7] kgdb: Remove irq flags and local_irq_enable/disable from roundup

2018-10-30 Thread Daniel Thompson 
On Mon, Oct 29, 2018 at 11:07:07AM -0700, Douglas Anderson wrote:
> The function kgdb_roundup_cpus() was passed a parameter that was
> documented as:
> 
> > the flags that will be used when restoring the interrupts. There is
> > local_irq_save() call before kgdb_roundup_cpus().
> 
> Nobody used those flags.  Anyone who wanted to temporarily turn on
> interrupts just did local_irq_enable() and local_irq_disable() without
> looking at them.  So we can definitely remove the flags.

On the whole I'd rather that this change...


> Speaking of calling local_irq_enable(), it seems like a bad idea and
> it caused a nice splat on my system with lockdep turned on.
> Specifically it hit:
>   DEBUG_LOCKS_WARN_ON(current->hardirq_context)

... and fixes for this this were in separate patches. They don't appear
especially related.


Daniel.

 
> See the previous patch in this series ("smp: Don't yell about IRQs
> disabled in kgdb_roundup_cpus()") for more details, but the last few
> things on the stack were this on my arm64 board:
>   lockdep_hardirqs_on+0xf0/0x160
>   trace_hardirqs_on+0x188/0x1ac
>   kgdb_roundup_cpus+0x14/0x3c
> 
> As agrued in the the commit text of ("smp: Don't yell about IRQs
> disabled in kgdb_roundup_cpus()"), it seems better to make
> smp_call_function() lenient about kgdb than to locally turn on IRQs
> here.  Thus let's totally remove all the local_irq_enable() and
> local_irq_disable() calls from all of the kgdb_roundup_cpus() calls.
> 
> Signed-off-by: Douglas Anderson 
> ---
> 
>  arch/arc/kernel/kgdb.c |  4 +---
>  arch/arm/kernel/kgdb.c |  4 +---
>  arch/arm64/kernel/kgdb.c   |  4 +---
>  arch/hexagon/kernel/kgdb.c | 11 ++-
>  arch/mips/kernel/kgdb.c|  4 +---
>  arch/powerpc/kernel/kgdb.c |  2 +-
>  arch/sh/kernel/kgdb.c  |  4 +---
>  arch/sparc/kernel/smp_64.c |  2 +-
>  arch/x86/kernel/kgdb.c |  9 ++---
>  include/linux/kgdb.h   |  9 ++---
>  kernel/debug/debug_core.c  |  2 +-
>  11 files changed, 14 insertions(+), 41 deletions(-)
> 
> diff --git a/arch/arc/kernel/kgdb.c b/arch/arc/kernel/kgdb.c
> index 9a3c34af2ae8..d94d3cb7f9e8 100644
> --- a/arch/arc/kernel/kgdb.c
> +++ b/arch/arc/kernel/kgdb.c
> @@ -197,11 +197,9 @@ static void kgdb_call_nmi_hook(void *ignored)
>   kgdb_nmicallback(raw_smp_processor_id(), NULL);
>  }
>  
> -void kgdb_roundup_cpus(unsigned long flags)
> +void kgdb_roundup_cpus(void)
>  {
> - local_irq_enable();
>   smp_call_function(kgdb_call_nmi_hook, NULL, 0);
> - local_irq_disable();
>  }
>  
>  struct kgdb_arch arch_kgdb_ops = {
> diff --git a/arch/arm/kernel/kgdb.c b/arch/arm/kernel/kgdb.c
> index caa0dbe3dc61..a80e9259f7e9 100644
> --- a/arch/arm/kernel/kgdb.c
> +++ b/arch/arm/kernel/kgdb.c
> @@ -175,11 +175,9 @@ static void kgdb_call_nmi_hook(void *ignored)
> kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
>  }
>  
> -void kgdb_roundup_cpus(unsigned long flags)
> +void kgdb_roundup_cpus(void)
>  {
> -   local_irq_enable();
> smp_call_function(kgdb_call_nmi_hook, NULL, 0);
> -   local_irq_disable();
>  }
>  
>  static int __kgdb_notify(struct die_args *args, unsigned long cmd)
> diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c
> index a20de58061a8..5d171c26788f 100644
> --- a/arch/arm64/kernel/kgdb.c
> +++ b/arch/arm64/kernel/kgdb.c
> @@ -289,11 +289,9 @@ static void kgdb_call_nmi_hook(void *ignored)
>   kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
>  }
>  
> -void kgdb_roundup_cpus(unsigned long flags)
> +void kgdb_roundup_cpus(void)
>  {
> - local_irq_enable();
>   smp_call_function(kgdb_call_nmi_hook, NULL, 0);
> - local_irq_disable();
>  }
>  
>  static int __kgdb_notify(struct die_args *args, unsigned long cmd)
> diff --git a/arch/hexagon/kernel/kgdb.c b/arch/hexagon/kernel/kgdb.c
> index 16c24b22d0b2..30fbc491cf45 100644
> --- a/arch/hexagon/kernel/kgdb.c
> +++ b/arch/hexagon/kernel/kgdb.c
> @@ -119,17 +119,12 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned 
> long pc)
>  
>  /**
>   * kgdb_roundup_cpus - Get other CPUs into a holding pattern
> - * @flags: Current IRQ state
>   *
>   * On SMP systems, we need to get the attention of the other CPUs
>   * and get them be in a known state.  This should do what is needed
>   * to get the other CPUs to call kgdb_wait(). Note that on some arches,
>   * the NMI approach is not used for rounding up all the CPUs. For example,
> - * in case of MIPS, smp_call_function() is used to roundup CPUs. In
> - * this case, we have to make sure that interrupts are enabled before
> - * calling smp_call_function(). The argument to this function is
> - * the flags that will be used when restoring the interrupts. There is
> - * local_irq_save() call before kgdb_roundup_cpus().
> + * in case of MIPS, smp_call_function() is used to roundup CPUs.
>   *
>   * On non-SMP systems, this is not called.
>   */
> @@ -139,11 +134,9 @@ static void hexagon_kgdb_nmi_hook(void *ignored)
>   kgdb_nmic

[PATCH v2] ARC: IOC: panic if kernel was started with previously enabled IOC

2018-10-30 Thread Eugeniy Paltsev 
If IOC was already enabled (due to bootloader) it technically needs to
be reconfigured with aperture base,size corresponding to Linux memory
map which will certainly be different than uboot's. But disabling and
reenabling IOC when DMA might be potentially active is tricky business.
To avoid random memory issues later, just panic here and ask user to
upgrade bootloader to one which doesn't enable IOC.

This was actually seen as issue on some of the HSDK board with a version
of uboot which enabled IOC. There were random issues later with starting
of X or peripherals etc.

Also while I'm at it, replace hardcoded bits in ARC_REG_IO_COH_PARTIAL
and ARC_REG_IO_COH_ENABLE registers by definitions.

Inspired by: https://lkml.org/lkml/2018/1/19/557
Signed-off-by: Eugeniy Paltsev 
---
Changes v1->v2:
 * Fix regression: check for IOC existence before accessing to any IOC
   register.

 arch/arc/include/asm/cache.h |  2 ++
 arch/arc/mm/cache.c  | 25 ++---
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/arch/arc/include/asm/cache.h b/arch/arc/include/asm/cache.h
index ff7d3232764a..f393b663413e 100644
--- a/arch/arc/include/asm/cache.h
+++ b/arch/arc/include/asm/cache.h
@@ -113,7 +113,9 @@ extern unsigned long perip_base, perip_end;
 
 /* IO coherency related Auxiliary registers */
 #define ARC_REG_IO_COH_ENABLE  0x500
+#define ARC_IO_COH_ENABLE_BIT  BIT(0)
 #define ARC_REG_IO_COH_PARTIAL 0x501
+#define ARC_IO_COH_PARTIAL_BIT BIT(0)
 #define ARC_REG_IO_COH_AP0_BASE0x508
 #define ARC_REG_IO_COH_AP0_SIZE0x509
 
diff --git a/arch/arc/mm/cache.c b/arch/arc/mm/cache.c
index f2701c13a66b..1b913c90676a 100644
--- a/arch/arc/mm/cache.c
+++ b/arch/arc/mm/cache.c
@@ -1144,6 +1144,25 @@ noinline void __init arc_ioc_setup(void)
 {
unsigned int ioc_base, mem_sz;
 
+   /*
+* Disabling and reconfiguring of IOC are quite a tricky actions because
+* nobody knows what happens if there're IOC-ahndled tarnsactions in
+* flight when we're disabling IOC.
+*
+* And the problem is external DMA masters [that were initialized and
+* set in a bootlaoder that was executed before we got here] might
+* continue to send data to memory even at this point and we have
+* no way to prevent that.
+*
+* That said it's much safer to not enable IOC at all anywhere before
+* Linux kernel.
+*/
+   if (read_aux_reg(ARC_REG_IO_COH_ENABLE) & ARC_IO_COH_ENABLE_BIT)
+   panic("kernel was started with previously enabled IOC!\n");
+
+   if (!ioc_enable)
+   return;
+
/*
 * As for today we don't support both IOC and ZONE_HIGHMEM enabled
 * simultaneously. This happens because as of today IOC aperture covers
@@ -1187,8 +1206,8 @@ noinline void __init arc_ioc_setup(void)
panic("IOC Aperture start must be aligned to the size of the 
aperture");
 
write_aux_reg(ARC_REG_IO_COH_AP0_BASE, ioc_base >> 12);
-   write_aux_reg(ARC_REG_IO_COH_PARTIAL, 1);
-   write_aux_reg(ARC_REG_IO_COH_ENABLE, 1);
+   write_aux_reg(ARC_REG_IO_COH_PARTIAL, ARC_IO_COH_PARTIAL_BIT);
+   write_aux_reg(ARC_REG_IO_COH_ENABLE, ARC_IO_COH_ENABLE_BIT);
 
/* Re-enable L1 dcache */
__dc_enable();
@@ -1265,7 +1284,7 @@ void __init arc_cache_init_master(void)
if (is_isa_arcv2() && l2_line_sz && !slc_enable)
arc_slc_disable();
 
-   if (is_isa_arcv2() && ioc_enable)
+   if (is_isa_arcv2() && ioc_exists)
arc_ioc_setup();
 
if (is_isa_arcv2() && l2_line_sz && slc_enable) {
-- 
2.14.5


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Re: [PATCH 0/7] serial: Finish kgdb on qcom_geni; fix many lockdep splats w/ kgdb

2018-10-30 Thread Andy Shevchenko 
On Mon, Oct 29, 2018 at 11:07:00AM -0700, Douglas Anderson wrote:
> I started out this series trying to make sysrq work over the serial
> console on qcom_geni_serial, then fell into a rat's nest.
> 
> To solve the deadlock I faced when enabling sysrq I tried to borrow
> code from '8250_port.c' which avoided grabbing the port lock in
> console_write().  ...but since these days I try to run with lockdep on
> all the time, I found it caused an annoying lockdep splat (which I
> also reproduced on my rk3399 board).  ...so I instead changed my
> qcom_geni_serial solution to borrow code from 'msm_serial.c'
> 
> I wasn't super happy with the solution in 'msm_serial.c' though.  I
> don't like releasing the spinlock there.  Not only is it ugly but it
> means we are unlocking / re-locking _all the time_ even though sysrq
> characters are rare.  ...so I came up with what I think is a better
> solution and then implemented it for qcom_geni_serial.
> 
> Since I had a good way to test 8250-based UARTs, I also fixed that
> driver to use my new method.  When doing so, I ran into a missing
> msm_serial.c at all, so I didn't switch that (or all other serial
> drivers for that matter) to the new method.
> 
> After fixing all the above issues, I found the next lockdep splat in
> kgdb and I think I've worked around it in a good-enough way, but I'm
> much less confident about this.  Hopefully folks can take a look at
> it.
> 
> In general, patches earlier in this series should be "less
> controversial" and hopefully can land even if people don't like
> patches later in the series.  ;-)
> 
> Looking back, this is pretty much two series squashed that could be
> treated indepdently.  The first is a serial series and the second is a
> kgdb series.
> 
> For all serial patches I'd expect them to go through the tty tree once
> they've been reviewed.
> 
> If folks are OK w/ the 'smp' patch it probably should go in some core
> kernel tree.  The kgdb patch won't work without it, though, so to land
> that we'd need coordination between the folks landing that and the
> folks landing the 'smp' patch.

I have got only 0/7 and 5/7, everything okay with your mail client and other 
tools?

> 
> 
> Douglas Anderson (7):
>   serial: qcom_geni_serial: Finish supporting sysrq
>   serial: core: Allow processing sysrq at port unlock time
>   serial: qcom_geni_serial: Process sysrq at port unlock time
>   serial: core: Include console.h from serial_core.h
>   serial: 8250: Process sysrq at port unlock time
>   smp: Don't yell about IRQs disabled in kgdb_roundup_cpus()
>   kgdb: Remove irq flags and local_irq_enable/disable from roundup
> 
>  arch/arc/kernel/kgdb.c  |  4 +--
>  arch/arm/kernel/kgdb.c  |  4 +--
>  arch/arm64/kernel/kgdb.c|  4 +--
>  arch/hexagon/kernel/kgdb.c  | 11 ++
>  arch/mips/kernel/kgdb.c |  4 +--
>  arch/powerpc/kernel/kgdb.c  |  2 +-
>  arch/sh/kernel/kgdb.c   |  4 +--
>  arch/sparc/kernel/smp_64.c  |  2 +-
>  arch/x86/kernel/kgdb.c  |  9 ++---
>  drivers/tty/serial/8250/8250_aspeed_vuart.c |  6 +++-
>  drivers/tty/serial/8250/8250_fsl.c  |  6 +++-
>  drivers/tty/serial/8250/8250_omap.c |  6 +++-
>  drivers/tty/serial/8250/8250_port.c |  8 ++---
>  drivers/tty/serial/qcom_geni_serial.c   | 10 --
>  include/linux/kgdb.h|  9 ++---
>  include/linux/serial_core.h | 38 -
>  kernel/debug/debug_core.c   |  2 +-
>  kernel/smp.c|  4 ++-
>  18 files changed, 80 insertions(+), 53 deletions(-)
> 
> -- 
> 2.19.1.568.g152ad8e336-goog
> 

-- 
With Best Regards,
Andy Shevchenko



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Re: [PATCH 0/7] serial: Finish kgdb on qcom_geni; fix many lockdep splats w/ kgdb

2018-10-30 Thread Daniel Thompson 
On Mon, Oct 29, 2018 at 11:07:00AM -0700, Douglas Anderson wrote:
> Looking back, this is pretty much two series squashed that could be
> treated indepdently.  The first is a serial series and the second is a
> kgdb series.

Indeed.

I couldn't work out the link between the first 5 patches and the last 2
until I read this...

Is anything in the 01->05 patch set even related to kgdb? From the stack
traces it looks to me like the lock dep warning would trigger for any
sysrq. I think separating into two threads for v2 would be sensible.


Daniel.


> 
> For all serial patches I'd expect them to go through the tty tree once
> they've been reviewed.
> 
> If folks are OK w/ the 'smp' patch it probably should go in some core
> kernel tree.  The kgdb patch won't work without it, though, so to land
> that we'd need coordination between the folks landing that and the
> folks landing the 'smp' patch.
> 
> 
> Douglas Anderson (7):
>   serial: qcom_geni_serial: Finish supporting sysrq
>   serial: core: Allow processing sysrq at port unlock time
>   serial: qcom_geni_serial: Process sysrq at port unlock time
>   serial: core: Include console.h from serial_core.h
>   serial: 8250: Process sysrq at port unlock time
>   smp: Don't yell about IRQs disabled in kgdb_roundup_cpus()
>   kgdb: Remove irq flags and local_irq_enable/disable from roundup
> 
>  arch/arc/kernel/kgdb.c  |  4 +--
>  arch/arm/kernel/kgdb.c  |  4 +--
>  arch/arm64/kernel/kgdb.c|  4 +--
>  arch/hexagon/kernel/kgdb.c  | 11 ++
>  arch/mips/kernel/kgdb.c |  4 +--
>  arch/powerpc/kernel/kgdb.c  |  2 +-
>  arch/sh/kernel/kgdb.c   |  4 +--
>  arch/sparc/kernel/smp_64.c  |  2 +-
>  arch/x86/kernel/kgdb.c  |  9 ++---
>  drivers/tty/serial/8250/8250_aspeed_vuart.c |  6 +++-
>  drivers/tty/serial/8250/8250_fsl.c  |  6 +++-
>  drivers/tty/serial/8250/8250_omap.c |  6 +++-
>  drivers/tty/serial/8250/8250_port.c |  8 ++---
>  drivers/tty/serial/qcom_geni_serial.c   | 10 --
>  include/linux/kgdb.h|  9 ++---
>  include/linux/serial_core.h | 38 -
>  kernel/debug/debug_core.c   |  2 +-
>  kernel/smp.c|  4 ++-
>  18 files changed, 80 insertions(+), 53 deletions(-)
> 
> -- 
> 2.19.1.568.g152ad8e336-goog
> 

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Re: [PATCH v2] ARC: IOC: panic if kernel was started with previously enabled IOC

2018-10-30 Thread Vineet Gupta 
On 10/30/18 1:54 AM, Eugeniy Paltsev wrote:
> If IOC was already enabled (due to bootloader) it technically needs to
> be reconfigured with aperture base,size corresponding to Linux memory
> map which will certainly be different than uboot's. But disabling and
> reenabling IOC when DMA might be potentially active is tricky business.
> To avoid random memory issues later, just panic here and ask user to
> upgrade bootloader to one which doesn't enable IOC.
>
> This was actually seen as issue on some of the HSDK board with a version
> of uboot which enabled IOC. There were random issues later with starting
> of X or peripherals etc.
>
> Also while I'm at it, replace hardcoded bits in ARC_REG_IO_COH_PARTIAL
> and ARC_REG_IO_COH_ENABLE registers by definitions.
>
> Inspired by: https://lkml.org/lkml/2018/1/19/557
> Signed-off-by: Eugeniy Paltsev 
> ---
> Changes v1->v2:
>  * Fix regression: check for IOC existence before accessing to any IOC
>register.
>
...
...
>   arc_slc_disable();
>  
> - if (is_isa_arcv2() && ioc_enable)
> + if (is_isa_arcv2() && ioc_exists)
>   arc_ioc_setup();

Folded this hunk into existing patch in for-curr.

Thx,
-Vineet

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Re: [PATCH 6/7] smp: Don't yell about IRQs disabled in kgdb_roundup_cpus()

2018-10-30 Thread Daniel Thompson 
On Mon, Oct 29, 2018 at 11:07:06AM -0700, Douglas Anderson wrote:
> In kgdb_roundup_cpus() we've got code that looks like:
>   local_irq_enable();
>   smp_call_function(kgdb_call_nmi_hook, NULL, 0);
>   local_irq_disable();
> 
> In certain cases when we drop into kgdb (like with sysrq-g on a serial
> console) we'll get a big yell that looks like:
> 
>   sysrq: SysRq : DEBUG
>   [ cut here ]
>   DEBUG_LOCKS_WARN_ON(current->hardirq_context)
>   WARNING: CPU: 0 PID: 0 at .../kernel/locking/lockdep.c:2875 
> lockdep_hardirqs_on+0xf0/0x160
>   CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.19.0 #27
>   pstate: 604003c9 (nZCv DAIF +PAN -UAO)
>   pc : lockdep_hardirqs_on+0xf0/0x160
>   ...
>   Call trace:
>lockdep_hardirqs_on+0xf0/0x160
>trace_hardirqs_on+0x188/0x1ac
>kgdb_roundup_cpus+0x14/0x3c
>kgdb_cpu_enter+0x53c/0x5cc
>kgdb_handle_exception+0x180/0x1d4
>kgdb_compiled_brk_fn+0x30/0x3c
>brk_handler+0x134/0x178
>do_debug_exception+0xfc/0x178
>el1_dbg+0x18/0x78
>kgdb_breakpoint+0x34/0x58
>sysrq_handle_dbg+0x54/0x5c
>__handle_sysrq+0x114/0x21c
>handle_sysrq+0x30/0x3c
>qcom_geni_serial_isr+0x2dc/0x30c
>   ...
>   ...
>   irq event stamp: ...45
>   hardirqs last  enabled at (...44): [...] __do_softirq+0xd8/0x4e4
>   hardirqs last disabled at (...45): [...] el1_irq+0x74/0x130
>   softirqs last  enabled at (...42): [...] _local_bh_enable+0x2c/0x34
>   softirqs last disabled at (...43): [...] irq_exit+0xa8/0x100
>   ---[ end trace adf21f830c46e638 ]---
> 
> Let's add kgdb to the list of reasons not to warn in
> smp_call_function_many().  That will allow us (in a future patch) to
> stop calling local_irq_enable() which will get rid of the original
> splat.
> 
> NOTE: with this change comes the obvious question: will we start
> deadlocking more often now when we drop into the debugger.  I can't
> say that for sure one way or the other, but the fact that we do the
> same logic for "oops_in_progress" makes me feel like it shouldn't
> happen too often.  Also note that the old logic of turning on
> interrupts temporarily wasn't exactly safe since (I presume) that
> could have violated spin_lock_irqsave() semantics and ended up with a
> deadlock of its own.

This is part of the code to bring all the cores to a halt and since
the other cores are still running kgdb isn't yet able to use the fact
all the CPUs are halted to bend the rules. It is better for this code
to play by the rules if it can.

Is is possible to get the roundup functions to use a private csd
alongside smp_call_function_single_async()? We could add a helper
function to the debug core to avoid having to add cpu_online loops into
every kgdb_roundup_cpus() implementaton.


Daniel.



> 
> Signed-off-by: Douglas Anderson 
> ---
> 
>  kernel/smp.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/smp.c b/kernel/smp.c
> index 163c451af42e..bb581e58c8dc 100644
> --- a/kernel/smp.c
> +++ b/kernel/smp.c
> @@ -19,6 +19,7 @@
>  #include 
>  #include 
>  #include 
> +#include 
>  
>  #include "smpboot.h"
>  
> @@ -413,7 +414,8 @@ void smp_call_function_many(const struct cpumask *mask,
>* can't happen.
>*/
>   WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
> -  && !oops_in_progress && !early_boot_irqs_disabled);
> +  && !oops_in_progress && !early_boot_irqs_disabled
> +  && !in_dbg_master());
>  
>   /* Try to fastpath.  So, what's a CPU they want? Ignoring this one. */
>   cpu = cpumask_first_and(mask, cpu_online_mask);
> -- 
> 2.19.1.568.g152ad8e336-goog
> 

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Re: [PATCH] ARC: [plat-hsdk] Enable DW APB GPIO support

2018-10-30 Thread Vineet Gupta 
On 10/23/18 5:09 AM, Eugeniy Paltsev wrote:
> Enable GPIO support on HSDK. HSDK SoC includes Synopsys
> DesignWare DW_apb_gpio IP with 24 GPIOs mapped onto port A.
> 
> Signed-off-by: Eugeniy Paltsev 

@Alexey, u happy with this ?

-Vineet

> ---
>  arch/arc/boot/dts/hsdk.dts  | 15 +++
>  arch/arc/configs/hsdk_defconfig |  3 +++
>  2 files changed, 18 insertions(+)
> 
> diff --git a/arch/arc/boot/dts/hsdk.dts b/arch/arc/boot/dts/hsdk.dts
> index ef149f59929a..43f17b51ee89 100644
> --- a/arch/arc/boot/dts/hsdk.dts
> +++ b/arch/arc/boot/dts/hsdk.dts
> @@ -222,6 +222,21 @@
>   bus-width = <4>;
>   dma-coherent;
>   };
> +
> + gpio: gpio@3000 {
> + compatible = "snps,dw-apb-gpio";
> + reg = <0x3000 0x20>;
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + gpio_port_a: gpio-controller@0 {
> + compatible = "snps,dw-apb-gpio-port";
> + gpio-controller;
> + #gpio-cells = <2>;
> + snps,nr-gpios = <24>;
> + reg = <0>;
> + };
> + };
>   };
>  
>   memory@8000 {
> diff --git a/arch/arc/configs/hsdk_defconfig b/arch/arc/configs/hsdk_defconfig
> index 1dec2b4bc5e6..eca10b8baea5 100644
> --- a/arch/arc/configs/hsdk_defconfig
> +++ b/arch/arc/configs/hsdk_defconfig
> @@ -45,6 +45,9 @@ CONFIG_SERIAL_8250_CONSOLE=y
>  CONFIG_SERIAL_8250_DW=y
>  CONFIG_SERIAL_OF_PLATFORM=y
>  # CONFIG_HW_RANDOM is not set
> +CONFIG_GPIOLIB=y
> +CONFIG_GPIO_SYSFS=y
> +CONFIG_GPIO_DWAPB=y
>  # CONFIG_HWMON is not set
>  CONFIG_DRM=y
>  # CONFIG_DRM_FBDEV_EMULATION is not set
> 


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[PATCH v2 2/2] kgdb: Fix kgdb_roundup_cpus() for arches who used smp_call_function()

2018-10-30 Thread Douglas Anderson 
When I had lockdep turned on and dropped into kgdb I got a nice splat
on my system.  Specifically it hit:
  DEBUG_LOCKS_WARN_ON(current->hardirq_context)

Specifically it looked like this:
  sysrq: SysRq : DEBUG
  [ cut here ]
  DEBUG_LOCKS_WARN_ON(current->hardirq_context)
  WARNING: CPU: 0 PID: 0 at .../kernel/locking/lockdep.c:2875 
lockdep_hardirqs_on+0xf0/0x160
  CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.19.0 #27
  pstate: 604003c9 (nZCv DAIF +PAN -UAO)
  pc : lockdep_hardirqs_on+0xf0/0x160
  ...
  Call trace:
   lockdep_hardirqs_on+0xf0/0x160
   trace_hardirqs_on+0x188/0x1ac
   kgdb_roundup_cpus+0x14/0x3c
   kgdb_cpu_enter+0x53c/0x5cc
   kgdb_handle_exception+0x180/0x1d4
   kgdb_compiled_brk_fn+0x30/0x3c
   brk_handler+0x134/0x178
   do_debug_exception+0xfc/0x178
   el1_dbg+0x18/0x78
   kgdb_breakpoint+0x34/0x58
   sysrq_handle_dbg+0x54/0x5c
   __handle_sysrq+0x114/0x21c
   handle_sysrq+0x30/0x3c
   qcom_geni_serial_isr+0x2dc/0x30c
  ...
  ...
  irq event stamp: ...45
  hardirqs last  enabled at (...44): [...] __do_softirq+0xd8/0x4e4
  hardirqs last disabled at (...45): [...] el1_irq+0x74/0x130
  softirqs last  enabled at (...42): [...] _local_bh_enable+0x2c/0x34
  softirqs last disabled at (...43): [...] irq_exit+0xa8/0x100
  ---[ end trace adf21f830c46e638 ]---

Looking closely at it, it seems like a really bad idea to be calling
local_irq_enable() in kgdb_roundup_cpus().  If nothing else that seems
like it could violate spinlock semantics and cause a deadlock.

Instead, let's use a private csd alongside
smp_call_function_single_async() to round up the other CPUs.  Using
smp_call_function_single_async() doesn't require interrupts to be
enabled so we can remove the offending bit of code.

In order to avoid duplicating this across all the architectures that
use the default kgdb_roundup_cpus(), we'll add a "weak" implementation
to debug_core.c.

Looking at all the people who previously had copies of this code,
there were a few variants.  I've attempted to keep the variants
working like they used to.  Specifically:
* For arch/arc we passed NULL to kgdb_nmicallback() instead of
  get_irq_regs().
* For arch/mips there was a bit of extra code around
  kgdb_nmicallback()

Suggested-by: Daniel Thompson 
Signed-off-by: Douglas Anderson 
---

Changes in v2:
- Removing irq flags separated from fixing lockdep splat.
- Don't use smp_call_function (Daniel).

 arch/arc/kernel/kgdb.c | 10 ++
 arch/arm/kernel/kgdb.c | 12 
 arch/arm64/kernel/kgdb.c   | 12 
 arch/hexagon/kernel/kgdb.c | 27 ---
 arch/mips/kernel/kgdb.c|  9 +
 arch/powerpc/kernel/kgdb.c |  4 ++--
 arch/sh/kernel/kgdb.c  | 12 
 include/linux/kgdb.h   | 15 +--
 kernel/debug/debug_core.c  | 36 
 9 files changed, 54 insertions(+), 83 deletions(-)

diff --git a/arch/arc/kernel/kgdb.c b/arch/arc/kernel/kgdb.c
index 0932851028e0..68d9fe4b5aa7 100644
--- a/arch/arc/kernel/kgdb.c
+++ b/arch/arc/kernel/kgdb.c
@@ -192,18 +192,12 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long 
ip)
instruction_pointer(regs) = ip;
 }
 
-static void kgdb_call_nmi_hook(void *ignored)
+void kgdb_call_nmi_hook(void *ignored)
 {
+   /* Default implementation passes get_irq_regs() but we don't */
kgdb_nmicallback(raw_smp_processor_id(), NULL);
 }
 
-void kgdb_roundup_cpus(void)
-{
-   local_irq_enable();
-   smp_call_function(kgdb_call_nmi_hook, NULL, 0);
-   local_irq_disable();
-}
-
 struct kgdb_arch arch_kgdb_ops = {
/* breakpoint instruction: TRAP_S 0x3 */
 #ifdef CONFIG_CPU_BIG_ENDIAN
diff --git a/arch/arm/kernel/kgdb.c b/arch/arm/kernel/kgdb.c
index f21077b077be..d9a69e941463 100644
--- a/arch/arm/kernel/kgdb.c
+++ b/arch/arm/kernel/kgdb.c
@@ -170,18 +170,6 @@ static struct undef_hook kgdb_compiled_brkpt_hook = {
.fn = kgdb_compiled_brk_fn
 };
 
-static void kgdb_call_nmi_hook(void *ignored)
-{
-   kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
-}
-
-void kgdb_roundup_cpus(void)
-{
-   local_irq_enable();
-   smp_call_function(kgdb_call_nmi_hook, NULL, 0);
-   local_irq_disable();
-}
-
 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
 {
struct pt_regs *regs = args->regs;
diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c
index 12c339ff6e75..da880247c734 100644
--- a/arch/arm64/kernel/kgdb.c
+++ b/arch/arm64/kernel/kgdb.c
@@ -284,18 +284,6 @@ static struct step_hook kgdb_step_hook = {
.fn = kgdb_step_brk_fn
 };
 
-static void kgdb_call_nmi_hook(void *ignored)
-{
-   kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
-}
-
-void kgdb_roundup_cpus(void)
-{
-   local_irq_enable();
-   smp_call_function(kgdb_call_nmi_hook, NULL, 0);
-   local_irq_disable();
-}
-
 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
 {

[PATCH v2 0/2] kgdb: Fix kgdb_roundup_cpus()

2018-10-30 Thread Douglas Anderson 
This series was originally part of the series ("serial: Finish kgdb on
qcom_geni; fix many lockdep splats w/ kgdb") but it made sense to
split it up.

It's believed that dropping into kgdb should be more robust once these
patches are applied.

Changes in v2:
- Removing irq flags separated from fixing lockdep splat.
- Don't use smp_call_function (Daniel).

Douglas Anderson (2):
  kgdb: Remove irq flags from roundup
  kgdb: Fix kgdb_roundup_cpus() for arches who used smp_call_function()

 arch/arc/kernel/kgdb.c | 10 ++
 arch/arm/kernel/kgdb.c | 12 
 arch/arm64/kernel/kgdb.c   | 12 
 arch/hexagon/kernel/kgdb.c | 32 
 arch/mips/kernel/kgdb.c|  9 +
 arch/powerpc/kernel/kgdb.c |  6 +++---
 arch/sh/kernel/kgdb.c  | 12 
 arch/sparc/kernel/smp_64.c |  2 +-
 arch/x86/kernel/kgdb.c |  9 ++---
 include/linux/kgdb.h   | 22 ++
 kernel/debug/debug_core.c  | 38 +-
 11 files changed, 60 insertions(+), 104 deletions(-)

-- 
2.19.1.568.g152ad8e336-goog


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[PATCH v2 1/2] kgdb: Remove irq flags from roundup

2018-10-30 Thread Douglas Anderson 
The function kgdb_roundup_cpus() was passed a parameter that was
documented as:

> the flags that will be used when restoring the interrupts. There is
> local_irq_save() call before kgdb_roundup_cpus().

Nobody used those flags.  Anyone who wanted to temporarily turn on
interrupts just did local_irq_enable() and local_irq_disable() without
looking at them.  So we can definitely remove the flags.

Signed-off-by: Douglas Anderson 
---

Changes in v2:
- Removing irq flags separated from fixing lockdep splat.

 arch/arc/kernel/kgdb.c | 2 +-
 arch/arm/kernel/kgdb.c | 2 +-
 arch/arm64/kernel/kgdb.c   | 2 +-
 arch/hexagon/kernel/kgdb.c | 9 ++---
 arch/mips/kernel/kgdb.c| 2 +-
 arch/powerpc/kernel/kgdb.c | 2 +-
 arch/sh/kernel/kgdb.c  | 2 +-
 arch/sparc/kernel/smp_64.c | 2 +-
 arch/x86/kernel/kgdb.c | 9 ++---
 include/linux/kgdb.h   | 9 ++---
 kernel/debug/debug_core.c  | 2 +-
 11 files changed, 14 insertions(+), 29 deletions(-)

diff --git a/arch/arc/kernel/kgdb.c b/arch/arc/kernel/kgdb.c
index 9a3c34af2ae8..0932851028e0 100644
--- a/arch/arc/kernel/kgdb.c
+++ b/arch/arc/kernel/kgdb.c
@@ -197,7 +197,7 @@ static void kgdb_call_nmi_hook(void *ignored)
kgdb_nmicallback(raw_smp_processor_id(), NULL);
 }
 
-void kgdb_roundup_cpus(unsigned long flags)
+void kgdb_roundup_cpus(void)
 {
local_irq_enable();
smp_call_function(kgdb_call_nmi_hook, NULL, 0);
diff --git a/arch/arm/kernel/kgdb.c b/arch/arm/kernel/kgdb.c
index caa0dbe3dc61..f21077b077be 100644
--- a/arch/arm/kernel/kgdb.c
+++ b/arch/arm/kernel/kgdb.c
@@ -175,7 +175,7 @@ static void kgdb_call_nmi_hook(void *ignored)
kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
 }
 
-void kgdb_roundup_cpus(unsigned long flags)
+void kgdb_roundup_cpus(void)
 {
local_irq_enable();
smp_call_function(kgdb_call_nmi_hook, NULL, 0);
diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c
index a20de58061a8..12c339ff6e75 100644
--- a/arch/arm64/kernel/kgdb.c
+++ b/arch/arm64/kernel/kgdb.c
@@ -289,7 +289,7 @@ static void kgdb_call_nmi_hook(void *ignored)
kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
 }
 
-void kgdb_roundup_cpus(unsigned long flags)
+void kgdb_roundup_cpus(void)
 {
local_irq_enable();
smp_call_function(kgdb_call_nmi_hook, NULL, 0);
diff --git a/arch/hexagon/kernel/kgdb.c b/arch/hexagon/kernel/kgdb.c
index 16c24b22d0b2..012e0e230ac2 100644
--- a/arch/hexagon/kernel/kgdb.c
+++ b/arch/hexagon/kernel/kgdb.c
@@ -119,17 +119,12 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long 
pc)
 
 /**
  * kgdb_roundup_cpus - Get other CPUs into a holding pattern
- * @flags: Current IRQ state
  *
  * On SMP systems, we need to get the attention of the other CPUs
  * and get them be in a known state.  This should do what is needed
  * to get the other CPUs to call kgdb_wait(). Note that on some arches,
  * the NMI approach is not used for rounding up all the CPUs. For example,
- * in case of MIPS, smp_call_function() is used to roundup CPUs. In
- * this case, we have to make sure that interrupts are enabled before
- * calling smp_call_function(). The argument to this function is
- * the flags that will be used when restoring the interrupts. There is
- * local_irq_save() call before kgdb_roundup_cpus().
+ * in case of MIPS, smp_call_function() is used to roundup CPUs.
  *
  * On non-SMP systems, this is not called.
  */
@@ -139,7 +134,7 @@ static void hexagon_kgdb_nmi_hook(void *ignored)
kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
 }
 
-void kgdb_roundup_cpus(unsigned long flags)
+void kgdb_roundup_cpus(void)
 {
local_irq_enable();
smp_call_function(hexagon_kgdb_nmi_hook, NULL, 0);
diff --git a/arch/mips/kernel/kgdb.c b/arch/mips/kernel/kgdb.c
index eb6c0d582626..2b05effc17b4 100644
--- a/arch/mips/kernel/kgdb.c
+++ b/arch/mips/kernel/kgdb.c
@@ -219,7 +219,7 @@ static void kgdb_call_nmi_hook(void *ignored)
set_fs(old_fs);
 }
 
-void kgdb_roundup_cpus(unsigned long flags)
+void kgdb_roundup_cpus(void)
 {
local_irq_enable();
smp_call_function(kgdb_call_nmi_hook, NULL, 0);
diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c
index 59c578f865aa..b0e804844be0 100644
--- a/arch/powerpc/kernel/kgdb.c
+++ b/arch/powerpc/kernel/kgdb.c
@@ -124,7 +124,7 @@ static int kgdb_call_nmi_hook(struct pt_regs *regs)
 }
 
 #ifdef CONFIG_SMP
-void kgdb_roundup_cpus(unsigned long flags)
+void kgdb_roundup_cpus(void)
 {
smp_send_debugger_break();
 }
diff --git a/arch/sh/kernel/kgdb.c b/arch/sh/kernel/kgdb.c
index 4f04c6638a4d..cc57630f6bf2 100644
--- a/arch/sh/kernel/kgdb.c
+++ b/arch/sh/kernel/kgdb.c
@@ -319,7 +319,7 @@ static void kgdb_call_nmi_hook(void *ignored)
kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
 }
 
-void kgdb_roundup_cpus(unsigned long flags)
+void kgdb_roundup_cpus(void)
 {
local_irq_enable();
smp_call_function(kgdb_call_nmi_hook,

Re: [PATCH 6/7] smp: Don't yell about IRQs disabled in kgdb_roundup_cpus()

2018-10-30 Thread Doug Anderson 
Daniel,

On Tue, Oct 30, 2018 at 2:42 AM Daniel Thompson
 wrote:
>
> On Mon, Oct 29, 2018 at 11:07:06AM -0700, Douglas Anderson wrote:
> > In kgdb_roundup_cpus() we've got code that looks like:
> >   local_irq_enable();
> >   smp_call_function(kgdb_call_nmi_hook, NULL, 0);
> >   local_irq_disable();
> >
> > In certain cases when we drop into kgdb (like with sysrq-g on a serial
> > console) we'll get a big yell that looks like:
> >
> >   sysrq: SysRq : DEBUG
> >   [ cut here ]
> >   DEBUG_LOCKS_WARN_ON(current->hardirq_context)
> >   WARNING: CPU: 0 PID: 0 at .../kernel/locking/lockdep.c:2875 
> > lockdep_hardirqs_on+0xf0/0x160
> >   CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.19.0 #27
> >   pstate: 604003c9 (nZCv DAIF +PAN -UAO)
> >   pc : lockdep_hardirqs_on+0xf0/0x160
> >   ...
> >   Call trace:
> >lockdep_hardirqs_on+0xf0/0x160
> >trace_hardirqs_on+0x188/0x1ac
> >kgdb_roundup_cpus+0x14/0x3c
> >kgdb_cpu_enter+0x53c/0x5cc
> >kgdb_handle_exception+0x180/0x1d4
> >kgdb_compiled_brk_fn+0x30/0x3c
> >brk_handler+0x134/0x178
> >do_debug_exception+0xfc/0x178
> >el1_dbg+0x18/0x78
> >kgdb_breakpoint+0x34/0x58
> >sysrq_handle_dbg+0x54/0x5c
> >__handle_sysrq+0x114/0x21c
> >handle_sysrq+0x30/0x3c
> >qcom_geni_serial_isr+0x2dc/0x30c
> >   ...
> >   ...
> >   irq event stamp: ...45
> >   hardirqs last  enabled at (...44): [...] __do_softirq+0xd8/0x4e4
> >   hardirqs last disabled at (...45): [...] el1_irq+0x74/0x130
> >   softirqs last  enabled at (...42): [...] _local_bh_enable+0x2c/0x34
> >   softirqs last disabled at (...43): [...] irq_exit+0xa8/0x100
> >   ---[ end trace adf21f830c46e638 ]---
> >
> > Let's add kgdb to the list of reasons not to warn in
> > smp_call_function_many().  That will allow us (in a future patch) to
> > stop calling local_irq_enable() which will get rid of the original
> > splat.
> >
> > NOTE: with this change comes the obvious question: will we start
> > deadlocking more often now when we drop into the debugger.  I can't
> > say that for sure one way or the other, but the fact that we do the
> > same logic for "oops_in_progress" makes me feel like it shouldn't
> > happen too often.  Also note that the old logic of turning on
> > interrupts temporarily wasn't exactly safe since (I presume) that
> > could have violated spin_lock_irqsave() semantics and ended up with a
> > deadlock of its own.
>
> This is part of the code to bring all the cores to a halt and since
> the other cores are still running kgdb isn't yet able to use the fact
> all the CPUs are halted to bend the rules. It is better for this code
> to play by the rules if it can.
>
> Is is possible to get the roundup functions to use a private csd
> alongside smp_call_function_single_async()? We could add a helper
> function to the debug core to avoid having to add cpu_online loops into
> every kgdb_roundup_cpus() implementaton.

Exactly the kind of helpful suggestion I was looking for.  Thank you
very much!  See v2 and hopefully it matches what you were thinking of.

-Doug

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Re: [PATCH 0/7] serial: Finish kgdb on qcom_geni; fix many lockdep splats w/ kgdb

2018-10-30 Thread Doug Anderson 
Hi,

On Tue, Oct 30, 2018 at 4:56 AM Daniel Thompson
 wrote:
>
> On Mon, Oct 29, 2018 at 11:07:00AM -0700, Douglas Anderson wrote:
> > Looking back, this is pretty much two series squashed that could be
> > treated indepdently.  The first is a serial series and the second is a
> > kgdb series.
>
> Indeed.
>
> I couldn't work out the link between the first 5 patches and the last 2
> until I read this...
>
> Is anything in the 01->05 patch set even related to kgdb? From the stack
> traces it looks to me like the lock dep warning would trigger for any
> sysrq. I think separating into two threads for v2 would be sensible.

Yes, sorry about the mess.  Splitting this into two series makes the
most sense.  Then I can focus more on trying to get the CCs right and
people can just get the patches that matter to them.

OK, I've sent v2 of both series out now.  Please yell if you can't
find them for whatever reason.

-Doug

-Doug

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Re: [PATCH 7/7] kgdb: Remove irq flags and local_irq_enable/disable from roundup

2018-10-30 Thread Doug Anderson 
Hi,

On Tue, Oct 30, 2018 at 4:46 AM Daniel Thompson
 wrote:
>
> On Mon, Oct 29, 2018 at 11:07:07AM -0700, Douglas Anderson wrote:
> > The function kgdb_roundup_cpus() was passed a parameter that was
> > documented as:
> >
> > > the flags that will be used when restoring the interrupts. There is
> > > local_irq_save() call before kgdb_roundup_cpus().
> >
> > Nobody used those flags.  Anyone who wanted to temporarily turn on
> > interrupts just did local_irq_enable() and local_irq_disable() without
> > looking at them.  So we can definitely remove the flags.
>
> On the whole I'd rather that this change...
>
>
> > Speaking of calling local_irq_enable(), it seems like a bad idea and
> > it caused a nice splat on my system with lockdep turned on.
> > Specifically it hit:
> >   DEBUG_LOCKS_WARN_ON(current->hardirq_context)
>
> ... and fixes for this this were in separate patches. They don't appear
> especially related.

Agreed that this is cleaner.  Done for v2.

-Doug

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[PATCH v2 0/6] arm64: Get rid of __early_init_dt_declare_initrd()

2018-10-30 Thread Florian Fainelli 
Hi all,

Changes in v2:

- get rid of ARCH_HAS_PHYS_INITRD and instead define
  phys_initrd_start/phys_initrd_size in init/do_mounts_initrd.c

- make __early_init_dt_declare_initrd() account for ARM64 specific
  behavior with __va() when having CONFIG_DEBUG_VM enabled

- consolidate early_initrd() command line parsing into
  init/do_mounts_initrd.c

Because phys_initrd_start/phys_initrd_size are now compiled in
ini/do_mounts_initrd.c which is only built with CONFIG_BLK_DEV_INITRD=y,
we need to be a bit careful about the uses throughout architecture
specific code.

Previous discussions/submissions list here:

v3:
https://www.spinics.net/lists/arm-kernel/msg683566.html
v2:
https://lkml.org/lkml/2018/10/25/4

Florian Fainelli (6):
  nds32: Remove phys_initrd_start and phys_initrd_size
  arch: Make phys_initrd_start and phys_initrd_size global variables
  of/fdt: Populate phys_initrd_start/phys_initrd_size from FDT
  arm64: Utilize phys_initrd_start/phys_initrd_size
  of/fdt: Remove custom __early_init_dt_declare_initrd() implementation
  arch: Move initrd= parsing into do_mounts_initrd.c

 arch/arc/mm/init.c  | 25 +--
 arch/arm/mm/init.c  | 28 ++
 arch/arm64/include/asm/memory.h |  8 
 arch/arm64/mm/init.c| 35 +++--
 arch/nds32/mm/init.c|  2 --
 arch/unicore32/mm/init.c| 24 +-
 drivers/of/fdt.c| 11 +--
 include/linux/initrd.h  |  3 +++
 init/do_mounts_initrd.c | 20 +++
 9 files changed, 51 insertions(+), 105 deletions(-)

-- 
2.17.1


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[PATCH v2 3/6] of/fdt: Populate phys_initrd_start/phys_initrd_size from FDT

2018-10-30 Thread Florian Fainelli 
Now that we have central and global variables holding the physical
address and size of the initrd, we can have
early_init_dt_check_for_initrd() populate
phys_initrd_start/phys_initrd_size for us.

This allows us to remove a chunk of code from arch/arm/mm/init.c
introduced with commit 65939301acdb ("arm: set initrd_start/initrd_end
for fdt scan").

Signed-off-by: Florian Fainelli 
---
 arch/arm/mm/init.c | 6 --
 drivers/of/fdt.c   | 2 ++
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 87d59a53861d..4bfa08e27319 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -236,12 +236,6 @@ static void __init arm_initrd_init(void)
phys_addr_t start;
unsigned long size;
 
-   /* FDT scan will populate initrd_start */
-   if (initrd_start && !phys_initrd_size) {
-   phys_initrd_start = __virt_to_phys(initrd_start);
-   phys_initrd_size = initrd_end - initrd_start;
-   }
-
initrd_start = initrd_end = 0;
 
if (!phys_initrd_size)
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 76c83c1ffeda..e34cb49231b5 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -925,6 +925,8 @@ static void __init early_init_dt_check_for_initrd(unsigned 
long node)
end = of_read_number(prop, len/4);
 
__early_init_dt_declare_initrd(start, end);
+   phys_initrd_start = start;
+   phys_initrd_size = end - start;
 
pr_debug("initrd_start=0x%llx  initrd_end=0x%llx\n",
 (unsigned long long)start, (unsigned long long)end);
-- 
2.17.1


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[PATCH v2 1/6] nds32: Remove phys_initrd_start and phys_initrd_size

2018-10-30 Thread Florian Fainelli 
This will conflict with a subsequent change making phys_initrd_start and
phys_initrd_size global variables. nds32 does not make use of those nor
provides a suitable declarations so just get rid of them.

Signed-off-by: Florian Fainelli 
---
 arch/nds32/mm/init.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/nds32/mm/init.c b/arch/nds32/mm/init.c
index c713d2ad55dc..32f55a24ccbb 100644
--- a/arch/nds32/mm/init.c
+++ b/arch/nds32/mm/init.c
@@ -22,8 +22,6 @@
 DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
 DEFINE_SPINLOCK(anon_alias_lock);
 extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
-extern unsigned long phys_initrd_start;
-extern unsigned long phys_initrd_size;
 
 /*
  * empty_zero_page is a special page that is used for
-- 
2.17.1


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[PATCH v2 6/6] arch: Move initrd= parsing into do_mounts_initrd.c

2018-10-30 Thread Florian Fainelli 
ARC, ARM, ARM64 and Unicore32 are all capable of parsing the "initrd="
command line parameter to allow specifying the physical address and size
of an initrd. Move that parsing into init/do_mounts_initrd.c such that
we no longer duplicate that logic.

Signed-off-by: Florian Fainelli 
---
 arch/arc/mm/init.c   | 25 +
 arch/arm/mm/init.c   | 17 -
 arch/arm64/mm/init.c | 18 --
 arch/unicore32/mm/init.c | 18 --
 init/do_mounts_initrd.c  | 17 +
 5 files changed, 22 insertions(+), 73 deletions(-)

diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c
index ba145065c579..369d3d699929 100644
--- a/arch/arc/mm/init.c
+++ b/arch/arc/mm/init.c
@@ -79,24 +79,6 @@ void __init early_init_dt_add_memory_arch(u64 base, u64 size)
base, TO_MB(size), !in_use ? "Not used":"");
 }
 
-#ifdef CONFIG_BLK_DEV_INITRD
-static int __init early_initrd(char *p)
-{
-   unsigned long start, size;
-   char *endp;
-
-   start = memparse(p, &endp);
-   if (*endp == ',') {
-   size = memparse(endp + 1, NULL);
-
-   initrd_start = (unsigned long)__va(start);
-   initrd_end = (unsigned long)__va(start + size);
-   }
-   return 0;
-}
-early_param("initrd", early_initrd);
-#endif
-
 /*
  * First memory setup routine called from setup_arch()
  * 1. setup swapper's mm @init_mm
@@ -141,8 +123,11 @@ void __init setup_arch_memory(void)
memblock_reserve(low_mem_start, __pa(_end) - low_mem_start);
 
 #ifdef CONFIG_BLK_DEV_INITRD
-   if (initrd_start)
-   memblock_reserve(__pa(initrd_start), initrd_end - initrd_start);
+   if (phys_initrd_size) {
+   memblock_reserve(phys_initrd_start, phys_initrd_size);
+   initrd_start = __va(phys_initrd_start);
+   initrd_end = initrd_start + phys_initrd_size;
+   }
 #endif
 
early_init_fdt_reserve_self();
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 4bfa08e27319..58ec68709606 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -52,23 +52,6 @@ unsigned long __init __clear_cr(unsigned long mask)
 #endif
 
 #ifdef CONFIG_BLK_DEV_INITRD
-static int __init early_initrd(char *p)
-{
-   phys_addr_t start;
-   unsigned long size;
-   char *endp;
-
-   start = memparse(p, &endp);
-   if (*endp == ',') {
-   size = memparse(endp + 1, NULL);
-
-   phys_initrd_start = start;
-   phys_initrd_size = size;
-   }
-   return 0;
-}
-early_param("initrd", early_initrd);
-
 static int __init parse_tag_initrd(const struct tag *tag)
 {
pr_warn("ATAG_INITRD is deprecated; "
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index e95cee656a55..9045afacd10b 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -62,24 +62,6 @@
 s64 memstart_addr __ro_after_init = -1;
 phys_addr_t arm64_dma_phys_limit __ro_after_init;
 
-#ifdef CONFIG_BLK_DEV_INITRD
-static int __init early_initrd(char *p)
-{
-   unsigned long start, size;
-   char *endp;
-
-   start = memparse(p, &endp);
-   if (*endp == ',') {
-   size = memparse(endp + 1, NULL);
-
-   phys_initrd_start = start;
-   phys_initrd_size = size;
-   }
-   return 0;
-}
-early_param("initrd", early_initrd);
-#endif
-
 #ifdef CONFIG_KEXEC_CORE
 /*
  * reserve_crashkernel() - reserves memory for crash kernel
diff --git a/arch/unicore32/mm/init.c b/arch/unicore32/mm/init.c
index f2f815d46846..99acdb829a7e 100644
--- a/arch/unicore32/mm/init.c
+++ b/arch/unicore32/mm/init.c
@@ -31,24 +31,6 @@
 
 #include "mm.h"
 
-#ifdef CONFIG_BLK_DEV_INITRD
-static int __init early_initrd(char *p)
-{
-   unsigned long start, size;
-   char *endp;
-
-   start = memparse(p, &endp);
-   if (*endp == ',') {
-   size = memparse(endp + 1, NULL);
-
-   phys_initrd_start = start;
-   phys_initrd_size = size;
-   }
-   return 0;
-}
-early_param("initrd", early_initrd);
-#endif
-
 /*
  * This keeps memory configuration data used by a couple memory
  * initialization functions, as well as show_mem() for the skipping
diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c
index 45865b72f4ea..732d21f4a637 100644
--- a/init/do_mounts_initrd.c
+++ b/init/do_mounts_initrd.c
@@ -27,6 +27,23 @@ static int __init no_initrd(char *str)
 
 __setup("noinitrd", no_initrd);
 
+static int __init early_initrd(char *p)
+{
+   phys_addr_t start;
+   unsigned long size;
+   char *endp;
+
+   start = memparse(p, &endp);
+   if (*endp == ',') {
+   size = memparse(endp + 1, NULL);
+
+   phys_initrd_start = start;
+   phys_initrd_size = size;
+   }
+   return 0;
+}
+early_param("initrd", early_initrd);
+
 static int init_linuxrc(struct subprocess_info *info, struct cred *new)
 {
ksys_unshare(CLONE_FS

[PATCH v2 2/6] arch: Make phys_initrd_start and phys_initrd_size global variables

2018-10-30 Thread Florian Fainelli 
Make phys_initrd_start and phys_initrd_size global variables declared in
init/do_mounts_initrd.c such that we can later have generic code in
drivers/of/fdt.c populate those variables for us.

This requires both the ARM and unicore32 implementations to be properly
guarded against CONFIG_BLK_DEV_INITRD, and also initialize the variables
to the expected default values (unicore32).

Signed-off-by: Florian Fainelli 
---
 arch/arm/mm/init.c   |  5 ++---
 arch/unicore32/mm/init.c | 10 +++---
 include/linux/initrd.h   |  3 +++
 init/do_mounts_initrd.c  |  3 +++
 4 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 0cc8e04295a4..87d59a53861d 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -51,9 +51,7 @@ unsigned long __init __clear_cr(unsigned long mask)
 }
 #endif
 
-static phys_addr_t phys_initrd_start __initdata = 0;
-static unsigned long phys_initrd_size __initdata = 0;
-
+#ifdef CONFIG_BLK_DEV_INITRD
 static int __init early_initrd(char *p)
 {
phys_addr_t start;
@@ -90,6 +88,7 @@ static int __init parse_tag_initrd2(const struct tag *tag)
 }
 
 __tagtable(ATAG_INITRD2, parse_tag_initrd2);
+#endif
 
 static void __init find_limits(unsigned long *min, unsigned long *max_low,
   unsigned long *max_high)
diff --git a/arch/unicore32/mm/init.c b/arch/unicore32/mm/init.c
index 8f8699e62bd5..f2f815d46846 100644
--- a/arch/unicore32/mm/init.c
+++ b/arch/unicore32/mm/init.c
@@ -31,9 +31,7 @@
 
 #include "mm.h"
 
-static unsigned long phys_initrd_start __initdata = 0x0100;
-static unsigned long phys_initrd_size __initdata = SZ_8M;
-
+#ifdef CONFIG_BLK_DEV_INITRD
 static int __init early_initrd(char *p)
 {
unsigned long start, size;
@@ -49,6 +47,7 @@ static int __init early_initrd(char *p)
return 0;
 }
 early_param("initrd", early_initrd);
+#endif
 
 /*
  * This keeps memory configuration data used by a couple memory
@@ -157,6 +156,11 @@ void __init uc32_memblock_init(struct meminfo *mi)
memblock_reserve(__pa(_text), _end - _text);
 
 #ifdef CONFIG_BLK_DEV_INITRD
+   if (!phys_initrd_size) {
+   phys_initrd_start = 0x0100;
+   phys_initrd_size = SZ_8M;
+   }
+
if (phys_initrd_size) {
memblock_reserve(phys_initrd_start, phys_initrd_size);
 
diff --git a/include/linux/initrd.h b/include/linux/initrd.h
index 84b423044088..14beaff9b445 100644
--- a/include/linux/initrd.h
+++ b/include/linux/initrd.h
@@ -21,4 +21,7 @@ extern int initrd_below_start_ok;
 extern unsigned long initrd_start, initrd_end;
 extern void free_initrd_mem(unsigned long, unsigned long);
 
+extern phys_addr_t phys_initrd_start;
+extern unsigned long phys_initrd_size;
+
 extern unsigned int real_root_dev;
diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c
index d1a5d885ce13..45865b72f4ea 100644
--- a/init/do_mounts_initrd.c
+++ b/init/do_mounts_initrd.c
@@ -16,6 +16,9 @@ int initrd_below_start_ok;
 unsigned int real_root_dev;/* do_proc_dointvec cannot handle kdev_t */
 static int __initdata mount_initrd = 1;
 
+phys_addr_t phys_initrd_start __initdata;
+unsigned long phys_initrd_size __initdata;
+
 static int __init no_initrd(char *str)
 {
mount_initrd = 0;
-- 
2.17.1


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[PATCH v2 4/6] arm64: Utilize phys_initrd_start/phys_initrd_size

2018-10-30 Thread Florian Fainelli 
ARM64 is the only architecture that re-defines
__early_init_dt_declare_initrd() in order for that function to populate
initrd_start/initrd_end with physical addresses instead of virtual
addresses. Instead of having an override we can leverage
drivers/of/fdt.c populating phys_initrd_start/phys_initrd_size to
populate those variables for us.

Signed-off-by: Florian Fainelli 
---
 arch/arm64/mm/init.c | 21 +
 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 3cf87341859f..e95cee656a55 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -72,8 +72,8 @@ static int __init early_initrd(char *p)
if (*endp == ',') {
size = memparse(endp + 1, NULL);
 
-   initrd_start = start;
-   initrd_end = start + size;
+   phys_initrd_start = start;
+   phys_initrd_size = size;
}
return 0;
 }
@@ -408,14 +408,14 @@ void __init arm64_memblock_init(void)
memblock_add(__pa_symbol(_text), (u64)(_end - _text));
}
 
-   if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && initrd_start) {
+   if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {
/*
 * Add back the memory we just removed if it results in the
 * initrd to become inaccessible via the linear mapping.
 * Otherwise, this is a no-op
 */
-   u64 base = initrd_start & PAGE_MASK;
-   u64 size = PAGE_ALIGN(initrd_end) - base;
+   u64 base = phys_initrd_start & PAGE_MASK;
+   u64 size = PAGE_ALIGN(phys_initrd_size);
 
/*
 * We can only add back the initrd memory if we don't end up
@@ -460,13 +460,10 @@ void __init arm64_memblock_init(void)
 */
memblock_reserve(__pa_symbol(_text), _end - _text);
 #ifdef CONFIG_BLK_DEV_INITRD
-   if (initrd_start) {
-   memblock_reserve(initrd_start, initrd_end - initrd_start);
-
-   /* the generic initrd code expects virtual addresses */
-   initrd_start = __phys_to_virt(initrd_start);
-   initrd_end = __phys_to_virt(initrd_end);
-   }
+   /* the generic initrd code expects virtual addresses */
+   initrd_start = __phys_to_virt(phys_initrd_start);
+   initrd_end = initrd_start + phys_initrd_size;
+   initrd_below_start_ok = 0;
 #endif
 
early_init_fdt_scan_reserved_mem();
-- 
2.17.1


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[PATCH v2 5/6] of/fdt: Remove custom __early_init_dt_declare_initrd() implementation

2018-10-30 Thread Florian Fainelli 
Now that ARM64 uses phys_initrd_start/phys_initrd_size, we can get rid
of its custom __early_init_dt_declare_initrd() which causes a fair
amount of objects rebuild when changing CONFIG_BLK_DEV_INITRD. In order
to make sure ARM64 does not produce a BUG() when VM debugging is turned
on though, we must avoid early calls to __va() which is what
__early_init_dt_declare_initrd() does and wrap this around to avoid
running that code on ARM64.

Signed-off-by: Florian Fainelli 
---
 arch/arm64/include/asm/memory.h | 8 
 drivers/of/fdt.c| 9 +++--
 2 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index b96442960aea..dc3ca21ba240 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -168,14 +168,6 @@
 #define IOREMAP_MAX_ORDER  (PMD_SHIFT)
 #endif
 
-#ifdef CONFIG_BLK_DEV_INITRD
-#define __early_init_dt_declare_initrd(__start, __end) \
-   do {\
-   initrd_start = (__start);   \
-   initrd_end = (__end);   \
-   } while (0)
-#endif
-
 #ifndef __ASSEMBLY__
 
 #include 
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index e34cb49231b5..f2b5becae96a 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -892,15 +892,20 @@ const void * __init of_flat_dt_match_machine(const void 
*default_match,
 }
 
 #ifdef CONFIG_BLK_DEV_INITRD
-#ifndef __early_init_dt_declare_initrd
 static void __early_init_dt_declare_initrd(unsigned long start,
   unsigned long end)
 {
+   /* ARM64 would cause a BUG to occur here when CONFIG_DEBUG_VM is
+* enabled since __va() is called too early. ARM64 does make use
+* of phys_initrd_start/phys_initrd_size so we can skip this
+* conversion.
+*/
+#if (!IS_ENABLED(CONFIG_ARM64))
initrd_start = (unsigned long)__va(start);
initrd_end = (unsigned long)__va(end);
initrd_below_start_ok = 1;
-}
 #endif
+}
 
 /**
  * early_init_dt_check_for_initrd - Decode initrd location from flat tree
-- 
2.17.1


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Re: [PATCH v2 2/2] kgdb: Fix kgdb_roundup_cpus() for arches who used smp_call_function()

2018-10-30 Thread kbuild test robot 
Hi Douglas,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on kgdb/kgdb-next]
[also build test WARNING on v4.19 next-20181030]
[if your patch is applied to the wrong git tree, please drop us a note to help 
improve the system]

url:
https://github.com/0day-ci/linux/commits/Douglas-Anderson/kgdb-Fix-kgdb_roundup_cpus/20181031-063733
base:   https://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb.git 
kgdb-next
reproduce: make htmldocs

All warnings (new ones prefixed by >>):

   WARNING: convert(1) not found, for SVG to PDF conversion install ImageMagick 
(https://www.imagemagick.org)
   include/linux/srcu.h:175: warning: Function parameter or member 'p' not 
described in 'srcu_dereference_notrace'
   include/linux/srcu.h:175: warning: Function parameter or member 'sp' not 
described in 'srcu_dereference_notrace'
   include/linux/gfp.h:1: warning: no structured comments found
>> include/linux/kgdb.h:188: warning: Function parameter or member 'ignored' 
>> not described in 'kgdb_call_nmi_hook'
   include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' 
description in 'reg_query_regdb_wmm'
   include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' 
description in 'reg_query_regdb_wmm'
   include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' 
description in 'reg_query_regdb_wmm'
   include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' 
description in 'reg_query_regdb_wmm'
   include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' 
description in 'reg_query_regdb_wmm'
   include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' 
description in 'reg_query_regdb_wmm'
   include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' 
description in 'reg_query_regdb_wmm'
   include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' 
description in 'reg_query_regdb_wmm'
   include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' 
description in 'reg_query_regdb_wmm'
   include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' 
description in 'reg_query_regdb_wmm'
   include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' 
description in 'reg_query_regdb_wmm'
   include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' 
description in 'reg_query_regdb_wmm'
   include/net/cfg80211.h:4381: warning: Function parameter or member 
'wext.ibss' not described in 'wireless_dev'
   include/net/cfg80211.h:4381: warning: Function parameter or member 
'wext.connect' not described in 'wireless_dev'
   include/net/cfg80211.h:4381: warning: Function parameter or member 
'wext.keys' not described in 'wireless_dev'
   include/net/cfg80211.h:4381: warning: Function parameter or member 'wext.ie' 
not described in 'wireless_dev'
   include/net/cfg80211.h:4381: warning: Function parameter or member 
'wext.ie_len' not described in 'wireless_dev'
   include/net/cfg80211.h:4381: warning: Function parameter or member 
'wext.bssid' not described in 'wireless_dev'
   include/net/cfg80211.h:4381: warning: Function parameter or member 
'wext.ssid' not described in 'wireless_dev'
   include/net/cfg80211.h:4381: warning: Function parameter or member 
'wext.default_key' not described in 'wireless_dev'
   include/net/cfg80211.h:4381: warning: Function parameter or member 
'wext.default_mgmt_key' not described in 'wireless_dev'
   include/net/cfg80211.h:4381: warning: Function parameter or member 
'wext.prev_bssid_valid' not described in 'wireless_dev'
   include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' 
description in 'reg_query_regdb_wmm'
   include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' 
description in 'reg_query_regdb_wmm'
   include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' 
description in 'reg_query_regdb_wmm'
   include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' 
description in 'reg_query_regdb_wmm'
   include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' 
description in 'reg_query_regdb_wmm'
   include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' 
description in 'reg_query_regdb_wmm'
   include/net/cfg80211.h:4869: warning: Excess function parameter 'ptr' 
description in 'reg_query_r