Commit-ID: 5ebd4c22897dce65845807a9bd3a31cc4e142b53
Gitweb: http://git.kernel.org/tip/5ebd4c22897dce65845807a9bd3a31cc4e142b53
Author: Soeren Sandmann <sandmann@xxxxxxxxxxx>
AuthorDate: Wed, 28 Oct 2009 18:55:36 +0100
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Tue, 10 Nov 2009 04:15:32 +0100
highmem: Fix race in debug_kmap_atomic() which could cause warn_count to underflow
debug_kmap_atomic() tries to prevent ever printing more than 10
warnings, but it does so by testing whether an unsigned integer
is equal to 0. However, if the warning is caused by a nested
IRQ, then this counter may underflow and the stream of warnings
will never end.
Fix that by using a signed integer instead.
Signed-off-by: Soeren Sandmann Pedersen <sandmann@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: a.p.zijlstra@xxxxxxxxx
Cc: <stable@xxxxxxxxxx> # .31.x
LKML-Reference: <ye8zl7b8ktj.fsf@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
mm/highmem.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/highmem.c b/mm/highmem.c
index 25878cc..33587de 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -426,9 +426,9 @@ void __init page_address_init(void)
void debug_kmap_atomic(enum km_type type)
{
- static unsigned warn_count = 10;
+ static int warn_count = 10;
- if (unlikely(warn_count == 0))
+ if (unlikely(warn_count < 0))
return;
if (unlikely(in_interrupt())) {
--
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