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authorBart Van Assche <bvanassche@acm.org>2019-07-01 14:42:32 -0700
committerJens Axboe <axboe@kernel.dk>2019-07-02 07:33:52 -0600
commitecefd7958eb32602df07f12e9808598b2c2de84b (patch)
tree789bcf30a838d99b02237568dae0b215cc13f944 /test/io_uring_enter.c
parentbbb30995a0b4c9e3489aa5d66d1807425734b791 (diff)
downloadliburing-ecefd7958eb32602df07f12e9808598b2c2de84b.tar.gz
liburing-ecefd7958eb32602df07f12e9808598b2c2de84b.tar.bz2
Fix the use of memory barriers
Introduce the smp_load_acquire() and smp_store_release() macros. Fix synchronization in io_uring_cq_advance() and __io_uring_get_cqe(). Remove a superfluous local variable, if-test and write barrier from __io_uring_submit(). Remove a superfluous barrier from test/io_uring_enter.c. Cc: Stefan Hajnoczi <stefanha@redhat.com> Cc: Roman Penyaev <rpenyaev@suse.de> Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'test/io_uring_enter.c')
-rw-r--r--test/io_uring_enter.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/test/io_uring_enter.c b/test/io_uring_enter.c
index d6e407e..b25afd5 100644
--- a/test/io_uring_enter.c
+++ b/test/io_uring_enter.c
@@ -262,9 +262,11 @@ main(int argc, char **argv)
ktail = *sq->ktail;
sq->array[ktail & mask] = index;
++ktail;
- write_barrier();
- *sq->ktail = ktail;
- write_barrier();
+ /*
+ * Ensure that the kernel sees the SQE update before it sees the tail
+ * update.
+ */
+ smp_store_release(sq->ktail, ktail);
ret = io_uring_enter(ring.ring_fd, 1, 0, 0, NULL);
/* now check to see if our sqe was dropped */