diff options
| author | Mike Waychison <mikew@google.com> | 2005-09-30 00:01:27 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-09-29 15:41:42 -0700 |
| commit | 7644143cd6f7e029f3a8ea64f5fb0ab33ec39f72 (patch) | |
| tree | 253112e894c11c37a52ac93fe0f470fe990c2c18 /arch/x86_64 | |
| parent | 7d318d774789657c37a5e994a4a2cf59d4879ae7 (diff) | |
[PATCH] x86_64: Fix mce_log
The attempt to fixup the lockless mce log buffer introduced an infinite loop
when trying to find a free entry.
And:
Using rcu_dereference() to load mcelog.next doesn't seem to be sufficient
enough to ensure that mcelog.next is loaded each time around the loop in
mce_log(). Instead, use an explicit rmb() to ensure that the compiler gets it
right.
AK: turned the smp_wmbs into true wmbs to make sure they are not
reordered by the compiler on UP.
Signed-off-by: Mike Waychison <mikew@google.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/x86_64')
| -rw-r--r-- | arch/x86_64/kernel/mce.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/arch/x86_64/kernel/mce.c b/arch/x86_64/kernel/mce.c index 08203b07f4b..69541db5ff2 100644 --- a/arch/x86_64/kernel/mce.c +++ b/arch/x86_64/kernel/mce.c @@ -54,9 +54,12 @@ void mce_log(struct mce *mce) { unsigned next, entry; mce->finished = 0; - smp_wmb(); + wmb(); for (;;) { entry = rcu_dereference(mcelog.next); + /* The rmb forces the compiler to reload next in each + iteration */ + rmb(); for (;;) { /* When the buffer fills up discard new entries. Assume that the earlier errors are the more interesting. */ @@ -69,6 +72,7 @@ void mce_log(struct mce *mce) entry++; continue; } + break; } smp_rmb(); next = entry + 1; @@ -76,9 +80,9 @@ void mce_log(struct mce *mce) break; } memcpy(mcelog.entry + entry, mce, sizeof(struct mce)); - smp_wmb(); + wmb(); mcelog.entry[entry].finished = 1; - smp_wmb(); + wmb(); if (!test_and_set_bit(0, &console_logged)) notify_user = 1; |