Andrew Morton (on Wed, 30 Jul 2008 02:43:29 -0700) wrote: >On Tue, 29 Jul 2008 23:07:45 +1000 Simon Horman <horms@xxxxxxxxxxxx> wrote: > >> On Tue, Jul 29, 2008 at 10:47:09PM +1000, Keith Owens wrote: >> > Simon Horman (on Tue, 29 Jul 2008 19:47:20 +1000) wrote: >> > >Aesthetic issues aside is it safe to call up() if down_trylock() failed? >> > > >> > >arch/ia64/kernel/salinfo.c: In function `salinfo_work_to_do': >> > >arch/ia64/kernel/salinfo.c:195: warning: ignoring return value of `down_trylock' >> > > >> > >Signed-off-by: Simon Horman <horms@xxxxxxxxxxxx> >> > > >> > >Index: linux-2.6/arch/ia64/kernel/salinfo.c >> > >=================================================================== >> > >--- linux-2.6.orig/arch/ia64/kernel/salinfo.c 2008-07-29 19:06:33.000000000 +1000 >> > >+++ linux-2.6/arch/ia64/kernel/salinfo.c 2008-07-29 19:40:02.000000000 +1000 >> > >@@ -192,8 +192,8 @@ struct salinfo_platform_oemdata_parms { >> > > static void >> > > salinfo_work_to_do(struct salinfo_data *data) >> > > { >> > >- down_trylock(&data->mutex); >> > >- up(&data->mutex); >> > >+ if (down_trylock(&data->mutex) == 0) >> > >+ up(&data->mutex); >> > > } >> > > >> > > static void >> > >> > NAK. The whole point of this function is to set the mutex to the up >> > state, irrespective of whether it was already down or not. Tracking >> > the state of data->mutex in all the possible contexts is just too >> > fragile, especially since it can be modified from NMI context. >> > salinfo_work_to_do() ensures that the mtuex ends in the up state. > >boggle. I daren't look. > >> > To remove the warning, just stick '(void)' in front of down_trylock(). >> >> Thanks, will do. >> > >For gawd's sake add a comment there too. You mean like the comment that is already in there? /* Kick the mutex that tells user space that there is work to do. Instead of * trying to track the state of the mutex across multiple cpus, in user * context, interrupt context, non-maskable interrupt context and hotplug cpu, * it is far easier just to grab the mutex if it is free then release it. * * This routine must be called with data_saved_lock held, to make the down/up * operation atomic. */ -- To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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