From ddca3b80cef36cc668f924ef5154a79acb19ebd7 Mon Sep 17 00:00:00 2001 From: Guillaume Autran Date: Wed, 13 Jul 2005 01:10:45 -0700 Subject: [PATCH] [PATCH] ppc32: fix destroy_context() race condition 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 Acked-by: Benjamin Herrenschmidt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/asm-ppc/mmu_context.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/include/asm-ppc/mmu_context.h b/include/asm-ppc/mmu_context.h index ccabbce39d85..afe26ffc2e2d 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, -- 2.20.1