From: Guillaume Autran <gautran@mrv.com>
To: akpm@osdl.org
Cc: linuxppc-embedded@ozlabs.org
Subject: [PATCH] ppc32: fix destroy_context() race condition
Date: Tue, 12 Jul 2005 10:23:51 -0400 [thread overview]
Message-ID: <42D3D277.106@mrv.com> (raw)
Fix for a race condition when a task gets preempted by another task
while executing the destroy_context(...) in a FEW_CONTEXTS environment.
mm->context == NO_CONTEXT but the context_map may indicate all contexts
are in use.
The solution to this problem is to disable kernel preemption while
destroying a MMU context.
Signed-off-by: Guillaume Autran <gautran@mrv.com>
---
diff -Nru a/include/asm-ppc/mmu_context.h b/include/asm-ppc/mmu_context.h
--- a/include/asm-ppc/mmu_context.h 2005-06-17 15:48:29.000000000 -0400
+++ b/include/asm-ppc/mmu_context.h 2005-07-05 08:58:46.000000000 -0400
@@ -149,6 +149,7 @@
*/
static inline void destroy_context(struct mm_struct *mm)
{
+ preempt_disable();
if (mm->context != NO_CONTEXT) {
clear_bit(mm->context, context_map);
mm->context = NO_CONTEXT;
@@ -156,6 +157,7 @@
atomic_inc(&nr_free_contexts);
#endif
}
+ preempt_enable();
}
static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
next reply other threads:[~2005-07-12 14:22 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-07-12 14:23 Guillaume Autran [this message]
2005-07-12 16:39 ` [PATCH] ppc32: fix destroy_context() race condition Eugene Surovegin
2005-07-12 18:29 ` Guillaume Autran
2005-07-12 18:45 ` Eugene Surovegin
2005-07-13 0:09 ` Benjamin Herrenschmidt
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