The patch titled
Subject: ipc-semc-chance-memory-barrier-in-sem_lock-to-smp_rmb-fix
has been added to the -mm tree. Its filename is
ipc-semc-chance-memory-barrier-in-sem_lock-to-smp_rmb-fix.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/ipc-semc-chance-memory-barrier-in-sem_lock-to-smp_rmb-fix.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/ipc-semc-chance-memory-barrier-in-sem_lock-to-smp_rmb-fix.patch
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------------------------------------------------------
From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Subject: ipc-semc-chance-memory-barrier-in-sem_lock-to-smp_rmb-fix
update sem_lock() comment, from Davidlohr
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Cc: Rafael Aquini <aquini@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
ipc/sem.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff -puN ipc/sem.c~ipc-semc-chance-memory-barrier-in-sem_lock-to-smp_rmb-fix ipc/sem.c
--- a/ipc/sem.c~ipc-semc-chance-memory-barrier-in-sem_lock-to-smp_rmb-fix
+++ a/ipc/sem.c
@@ -327,10 +327,11 @@ static inline int sem_lock(struct sem_ar
/* Then check that the global lock is free */
if (!spin_is_locked(&sma->sem_perm.lock)) {
/*
- * The next test must happen after the test for
- * sem_perm.lock, otherwise we can race with another
- * thread that does
- * complex_count++;spin_unlock(sem_perm.lock);
+ * The ipc object lock check must be visible on all
+ * cores before rechecking the complex count. Otherwise
+ * we can race with another thread that does:
+ * complex_count++++;
+ * spin_unlock(sem_perm.lock);
*/
smp_rmb();
_
Patches currently in -mm which might be from akpm@xxxxxxxxxxxxxxxxxxxx are
origin.patch
i-need-old-gcc.patch
arch-alpha-kernel-systblss-remove-debug-check.patch
kernel-posix-timersc-code-clean-up-checkpatch-fixes.patch
input-route-kbd-leds-through-the-generic-leds-layer.patch
o2dlm-fix-null-pointer-dereference-in-o2dlm_blocking_ast_wrapper-checkpatch-fixes.patch
ocfs2-free-inode-when-i_count-becomes-zero.patch
ocfs2-do-not-fallback-to-buffer-i-o-write-if-fill-holes-checkpatch-fixes.patch
mm.patch
mm-memcontrol-lockless-page-counters-fix.patch
mm-memcontrol-lockless-page-counters-fix-fix.patch
mm-introduce-do_shared_fault-and-drop-do_fault-fix-fix.patch
do_shared_fault-check-that-mmap_sem-is-held.patch
fs-proc-use-a-rb-tree-for-the-directory-entries-fix.patch
rtc-pm8xxx-rework-to-support-pm8941-rtc-checkpatch-fixes.patch
ipc-semc-chance-memory-barrier-in-sem_lock-to-smp_rmb-fix.patch
linux-next.patch
linux-next-git-rejects.patch
drivers-gpio-gpio-zevioc-fix-build.patch
mm-replace-remap_file_pages-syscall-with-emulation.patch
debugging-keep-track-of-page-owners.patch
debugging-keep-track-of-page-owners-fix.patch
journal_add_journal_head-debug.patch
journal_add_journal_head-debug-fix.patch
kernel-forkc-export-kernel_thread-to-modules.patch
mutex-subsystem-synchro-test-module.patch
slab-leaks3-default-y.patch
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