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| author | Paolo Bonzini <pbonzini@redhat.com> | 2017-02-27 12:17:26 +0100 |
|---|---|---|
| committer | Peter Maydell <peter.maydell@linaro.org> | 2017-02-27 12:54:08 +0000 |
| commit | 3b1d8169844fafee184366b0e0d7080534758b4d (patch) | |
| tree | 8f494ceb20aecaeea0d11077de547e102a9ba54f /tests/test-aio-multithread.c | |
| parent | d992f2f1368ceb92e6bfd8efece174110f4236ff (diff) | |
| download | qemu-3b1d8169844fafee184366b0e0d7080534758b4d.zip qemu-3b1d8169844fafee184366b0e0d7080534758b4d.tar.gz qemu-3b1d8169844fafee184366b0e0d7080534758b4d.tar.bz2 | |
tests-aio-multithread: use atomic_read properly
nodes[id].next is written by other threads. If atomic_read is not used
(matching atomic_set in mcs_mutex_lock!) the compiler can optimize the
whole "if" away!
Reported-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Tested-by: Greg Kurz <groug@kaod.org>
Message-id: 20170227111726.9237-1-pbonzini@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'tests/test-aio-multithread.c')
| -rw-r--r-- | tests/test-aio-multithread.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/tests/test-aio-multithread.c b/tests/test-aio-multithread.c index f11e990..8b0b40e 100644 --- a/tests/test-aio-multithread.c +++ b/tests/test-aio-multithread.c @@ -309,7 +309,7 @@ static void mcs_mutex_lock(void) static void mcs_mutex_unlock(void) { int next; - if (nodes[id].next == -1) { + if (atomic_read(&nodes[id].next) == -1) { if (atomic_read(&mutex_head) == id && atomic_cmpxchg(&mutex_head, id, -1) == id) { /* Last item in the list, exit. */ @@ -323,7 +323,7 @@ static void mcs_mutex_unlock(void) } /* Wake up the next in line. */ - next = nodes[id].next; + next = atomic_read(&nodes[id].next); nodes[next].locked = 0; qemu_futex_wake(&nodes[next].locked, 1); } |