Messages in this thread | | | From | Keith Owens <> | Subject | Re: [patch] IA64: only call up() in salinfo_work_to_do() if down_trylock() was successful | Date | Tue, 29 Jul 2008 22:47:09 +1000 |
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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@verge.net.au> > >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.
To remove the warning, just stick '(void)' in front of down_trylock().
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