Messages in this thread | | | Date | Wed, 14 Jan 2009 12:44:01 +0100 | From | Joerg Roedel <> | Subject | Re: [PATCH 08/16] dma-debug: add core checking functions |
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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.
As I wrote in a previous email, a race here is no big deal. I add a comment to document it. Or do we want another global lock here?
> Also, please dont use a macro for this - printk details can be passed in > to helper inlines/functions too.
Hmm, how does this look like? There is not WARN variant which can use va_args as a parameter. And it is important that the error message is logged in the warning itself. So the driver developer can see it when a user reports the warning.
Joerg
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