On Mon, 14 Nov 2016 12:03:35 +0100
Uwe Kleine-König <u...@kleine-koenig.org> wrote:
> Make it possible to generate trace events for mdio read and write accesses.
>
> Signed-off-by: Uwe Kleine-König <u...@kleine-koenig.org>
> ---
> drivers/net/phy/mdio_bus.c | 15 +++++++++++++++
> include/trace/events/mdio.h | 40 ++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 55 insertions(+)
> create mode 100644 include/trace/events/mdio.h
>
> diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
> index 09deef4bed09..0f3f207419f6 100644
> --- a/drivers/net/phy/mdio_bus.c
> +++ b/drivers/net/phy/mdio_bus.c
> @@ -38,6 +38,9 @@
>
> #include <asm/irq.h>
>
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/mdio.h>
> +
> int mdiobus_register_device(struct mdio_device *mdiodev)
> {
> if (mdiodev->bus->mdio_map[mdiodev->addr])
> @@ -461,6 +464,9 @@ int mdiobus_read_nested(struct mii_bus *bus, int addr,
> u32 regnum)
> retval = bus->read(bus, addr, regnum);
> mutex_unlock(&bus->mdio_lock);
>
> + if (retval >= 0)
> + trace_mdio_access(bus, 1, addr, regnum, retval);
These cause branches to be taken when tracing is disabled, breaking the
zero overhead for disabled tracing guideline. As retval is passed to
the tracepoint, please look at TRACE_EVENT_CONDITION() and use that.
It will move the if statement into the enabling of the trace event and
keep the overhead to a minimum when the tracepoint is disabled.
Do the same for the below as well.
-- Steve
> +
> return retval;
> }
> EXPORT_SYMBOL(mdiobus_read_nested);
> @@ -485,6 +491,9 @@ int mdiobus_read(struct mii_bus *bus, int addr, u32
> regnum)
> retval = bus->read(bus, addr, regnum);
> mutex_unlock(&bus->mdio_lock);
>
> + if (retval >= 0)
> + trace_mdio_access(bus, 1, addr, regnum, retval);
> +
> return retval;
> }
> EXPORT_SYMBOL(mdiobus_read);
> @@ -513,6 +522,9 @@ int mdiobus_write_nested(struct mii_bus *bus, int addr,
> u32 regnum, u16 val)
> err = bus->write(bus, addr, regnum, val);
> mutex_unlock(&bus->mdio_lock);
>
> + if (!err)
> + trace_mdio_access(bus, 0, addr, regnum, val);
> +
> return err;
> }
> EXPORT_SYMBOL(mdiobus_write_nested);
> @@ -538,6 +550,9 @@ int mdiobus_write(struct mii_bus *bus, int addr, u32
> regnum, u16 val)
> err = bus->write(bus, addr, regnum, val);
> mutex_unlock(&bus->mdio_lock);
>
> + if (!err)
> + trace_mdio_access(bus, 0, addr, regnum, val);
> +
> return err;
> }
> EXPORT_SYMBOL(mdiobus_write);
> diff --git a/include/trace/events/mdio.h b/include/trace/events/mdio.h
> new file mode 100644
> index 000000000000..dcb2d456a346
> --- /dev/null
> +++ b/include/trace/events/mdio.h
> @@ -0,0 +1,40 @@
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM mdio
> +
> +#if !defined(_TRACE_MDIO_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_MDIO_H
> +
> +#include <linux/tracepoint.h>
> +
> +TRACE_EVENT(mdio_access,
> +
> + TP_PROTO(struct mii_bus *bus, int read,
> + unsigned addr, unsigned regnum, u16 val),
> +
> + TP_ARGS(bus, read, addr, regnum, val),
> +
> + TP_STRUCT__entry(
> + __array(char, busid, MII_BUS_ID_SIZE)
> + __field(int, read)
> + __field(unsigned, addr)
> + __field(unsigned, regnum)
> + __field(u16, val)
> + ),
> +
> + TP_fast_assign(
> + strncpy(__entry->busid, bus->id, MII_BUS_ID_SIZE);
> + __entry->read = read;
> + __entry->addr = addr;
> + __entry->regnum = regnum;
> + __entry->val = val;
> + ),
> +
> + TP_printk("%s %-5s phy:0x%02x reg:0x%02x val:0x%04hx",
> + __entry->busid, __entry->read ? "read" : "write",
> + __entry->addr, __entry->regnum, __entry->val)
> +);
> +
> +#endif /* if !defined(_TRACE_MDIO_H) || defined(TRACE_HEADER_MULTI_READ) */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
