On Thu, 13 Nov 2014 22:48:33 -0600 Alex Elder <[email protected]> wrote:
> > diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c > > index e748971..4790191 100644 > > --- a/kernel/printk/printk.c > > +++ b/kernel/printk/printk.c > > @@ -1624,7 +1624,7 @@ asmlinkage int vprintk_emit(int facility, int level, > > int printed_len = 0; > > bool in_sched = false; > > /* cpu currently holding logbuf_lock in this function */ > > - static volatile unsigned int logbuf_cpu = UINT_MAX; > > + static unsigned int logbuf_cpu = UINT_MAX; > > If this is not volatile, can the compiler assume that it > can't change before the first access? Put another way, > does this assignment need to be done more like this? > > static unsigned int ACCESS_ONCE(logbuf_cpu) = UINT_MAX; > > (I haven't checked, but I don't believe that expands to valid code.) > I can bet you that it doesn't compile. That assignment is what it is initialized to at boot up. I can't see any optimization that would cause gcc to modify that. Especially since we are hiding its accesses within the ACCESS_ONCE(). That alone should confuse gcc enough to leave it a hell alone J. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
