lkml.org 
[lkml]   [2009]   [Jan]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 08/16] dma-debug: add core checking functions
On Sun, Jan 11, 2009 at 12:11:27AM +0100, Ingo Molnar wrote:
>
> * Joerg Roedel <joerg.roedel@amd.com> wrote:
>
> > +#define err_printk(dev, format, arg...) do { \
> > + error_count += 1; \
> > + if (show_all_errors || show_num_errors > 0) { \
> > + WARN(1, "%s %s: " format, \
> > + dev_driver_string(dev), \
> > + dev_name(dev) , ## arg); \
> > + } \
> > + if (!show_all_errors && show_num_errors > 0) \
> > + show_num_errors -= 1; \
>
> Note that the arithmetics here is SMP-unsafe: we only hold the hash bucket
> so if two errors hit at once on two CPUs then the error tracking variables
> can be accessed at once.
>
> I'd suggest a simple global lock for this error case (taken inside the
> hash bucket lock), to be on the safe side.
>
> Also, please dont use a macro for this - printk details can be passed in
> to helper inlines/functions too.

Yeah, this is not SMP-safe, I know. But debugfs does not support
atomic_t so I made the variables u32. But at least a race condition has
not a too bad impact. What may habben is that error_count misses a error
or the show_num_errors become negative.
But if we really want to avoid this I think its better to add atomic_t
support to debugfs. What do you think?

Joerg


\
 
 \ /
  Last update: 2009-01-11 09:01    [W:0.092 / U:10.452 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site