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authorMaarten Lankhorst <maarten.lankhorst@canonical.com>2013-07-30 12:13:41 +0400
committerIngo Molnar <mingo@kernel.org>2013-07-31 00:16:40 +0400
commit85f4896123d0299128f2c95cc40f3b8b01d4b0f6 (patch)
treecadd786200b218479e020386c4aa77cdd15688e5
parent36f571e9ed0419e73d127e18aa8992ced867268c (diff)
downloadlinux-85f4896123d0299128f2c95cc40f3b8b01d4b0f6.tar.xz
mutex: Fix w/w mutex deadlock injection
The check needs to be for > 1, because ctx->acquired is already incremented. This will prevent ww_mutex_lock_slow from returning -EDEADLK and not locking the mutex. It caused a lot of false gpu lockups on radeon with CONFIG_DEBUG_WW_MUTEX_SLOWPATH=y because a function that shouldn't be able to return -EDEADLK did. Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Alex Deucher <alexander.deucher@amd.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/51F775B5.201@canonical.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--kernel/mutex.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/mutex.c b/kernel/mutex.c
index ff05f4bd86eb..a52ee7bb830d 100644
--- a/kernel/mutex.c
+++ b/kernel/mutex.c
@@ -686,7 +686,7 @@ __ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
might_sleep();
ret = __mutex_lock_common(&lock->base, TASK_UNINTERRUPTIBLE,
0, &ctx->dep_map, _RET_IP_, ctx);
- if (!ret && ctx->acquired > 0)
+ if (!ret && ctx->acquired > 1)
return ww_mutex_deadlock_injection(lock, ctx);
return ret;
@@ -702,7 +702,7 @@ __ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
ret = __mutex_lock_common(&lock->base, TASK_INTERRUPTIBLE,
0, &ctx->dep_map, _RET_IP_, ctx);
- if (!ret && ctx->acquired > 0)
+ if (!ret && ctx->acquired > 1)
return ww_mutex_deadlock_injection(lock, ctx);
return ret;