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authorNick Piggin <nickpiggin@yahoo.com.au>2008-08-12 18:05:13 +1000
committerIngo Molnar <mingo@elte.hu>2008-08-12 11:21:27 +0200
commitc2fc11985db304572322f1dcdcb0f71337315006 (patch)
tree330196cefd4eb0ad3b4999fb14518a62f0294d93 /kernel
parent23a0ee908cbfba3264d19729c67c22b20fa73886 (diff)
downloadop-kernel-dev-c2fc11985db304572322f1dcdcb0f71337315006.zip
op-kernel-dev-c2fc11985db304572322f1dcdcb0f71337315006.tar.gz
generic-ipi: fix stack and rcu interaction bug in smp_call_function_mask(), fix
> > Nick Piggin (1): > > generic-ipi: fix stack and rcu interaction bug in > > smp_call_function_mask() > > I'm still not 100% sure that I have this patch right... I might have seen > a lockup trace implicating the smp call function path... which may have > been due to some other problem or a different bug in the new call function > code, but if some more people can take a look at it before merging? OK indeed it did have a couple of bugs. Firstly, I wasn't freeing the data properly in the alloc && wait case. Secondly, I wasn't resetting CSD_FLAG_WAIT in the for each cpu loop (so only the first CPU would wait). After those fixes, the patch boots and runs with the kmalloc commented out (so it always executes the slowpath). Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/smp.c10
1 files changed, 6 insertions, 4 deletions
diff --git a/kernel/smp.c b/kernel/smp.c
index e6084f6..782e2b9 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -135,7 +135,8 @@ void generic_smp_call_function_interrupt(void)
*/
smp_wmb();
data->csd.flags &= ~CSD_FLAG_WAIT;
- } else
+ }
+ if (data->csd.flags & CSD_FLAG_ALLOC)
call_rcu(&data->rcu_head, rcu_free_call_data);
}
rcu_read_unlock();
@@ -289,10 +290,11 @@ static void smp_call_function_mask_quiesce_stack(cpumask_t mask)
data.func = quiesce_dummy;
data.info = NULL;
- data.flags = CSD_FLAG_WAIT;
- for_each_cpu_mask(cpu, mask)
+ for_each_cpu_mask(cpu, mask) {
+ data.flags = CSD_FLAG_WAIT;
generic_exec_single(cpu, &data);
+ }
}
/**
@@ -371,7 +373,7 @@ int smp_call_function_mask(cpumask_t mask, void (*func)(void *), void *info,
if (wait) {
csd_flag_wait(&data->csd);
if (unlikely(slowpath))
- smp_call_function_mask_quiesce_stack(allbutself);
+ smp_call_function_mask_quiesce_stack(mask);
}
return 0;
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