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author | 2022-08-26 09:17:08 -0400 | |
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committer | 2022-08-26 09:30:25 -0700 | |
commit | 8238b4579866b7c1bb99883cfe102a43db5506ff (patch) | |
tree | a61b3a10f1d6b53bc7c05b08b8b49bb84156ee2e /kernel/sched/wait_bit.c | |
parent | Merge tag 'net-6.0-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/netd... (diff) | |
download | linux-8238b4579866b7c1bb99883cfe102a43db5506ff.tar.gz linux-8238b4579866b7c1bb99883cfe102a43db5506ff.tar.bz2 linux-8238b4579866b7c1bb99883cfe102a43db5506ff.zip |
wait_on_bit: add an acquire memory barrier
There are several places in the kernel where wait_on_bit is not followed
by a memory barrier (for example, in drivers/md/dm-bufio.c:new_read).
On architectures with weak memory ordering, it may happen that memory
accesses that follow wait_on_bit are reordered before wait_on_bit and
they may return invalid data.
Fix this class of bugs by introducing a new function "test_bit_acquire"
that works like test_bit, but has acquire memory ordering semantics.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Acked-by: Will Deacon <will@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/sched/wait_bit.c')
-rw-r--r-- | kernel/sched/wait_bit.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched/wait_bit.c b/kernel/sched/wait_bit.c index d4788f810b55..0b1cd985dc27 100644 --- a/kernel/sched/wait_bit.c +++ b/kernel/sched/wait_bit.c @@ -47,7 +47,7 @@ __wait_on_bit(struct wait_queue_head *wq_head, struct wait_bit_queue_entry *wbq_ prepare_to_wait(wq_head, &wbq_entry->wq_entry, mode); if (test_bit(wbq_entry->key.bit_nr, wbq_entry->key.flags)) ret = (*action)(&wbq_entry->key, mode); - } while (test_bit(wbq_entry->key.bit_nr, wbq_entry->key.flags) && !ret); + } while (test_bit_acquire(wbq_entry->key.bit_nr, wbq_entry->key.flags) && !ret); finish_wait(wq_head, &wbq_entry->wq_entry); |