[PATCH] ppc32: fix destroy_context() race condition

ddca3b80 · Guillaume Autran <[email protected]> · 2005-07-13 01:10:45 -07:00

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 <[email protected]>
Acked-by: Benjamin Herrenschmidt <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Commit: ddca3b80cef36cc668f924ef5154a79acb19ebd7
Parents: 88bd5121

Changes

1 files changed · +2 −0

File	Status	Add	Del	Content
include/asm-ppc/mmu_context.h	modified	+2	−0	View file

include/asm-ppc/mmu_context.h

View file

diff --git a/include/asm-ppc/mmu_context.h b/include/asm-ppc/mmu_context.h
index ccabbce..afe26ff 100644
--- a/include/asm-ppc/mmu_context.h
+++ b/include/asm-ppc/mmu_context.h
@@ -149,6 +149,7 @@ static inline void get_mmu_context(struct mm_struct *mm)
  */
 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 @@ static inline void destroy_context(struct mm_struct *mm)
 		atomic_inc(&nr_free_contexts);
 #endif
 	}
+	preempt_enable();
 }
 
 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,