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aio-posix: signal-proof fdmon-io_uring 

The io_uring_enter(2) syscall returns with errno=EINTR when interrupted
by a signal.  Retry the syscall in this case.

It's essential to do this in the io_uring_submit_and_wait() case.  My
interpretation of the Linux v5.5 io_uring_enter(2) code is that it
shouldn't affect the io_uring_submit() case, but there is no guarantee
this will always be the case.  Let's check for -EINTR around both APIs.

Note that the liburing APIs have -errno return values.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20200408091139.273851-1-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2020-04-08 10:11:39 +01:00
parent 8bac3ba57e
commit 636b836d5f
1 changed files with 8 additions and 2 deletions
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10
util/fdmon-io_uring.c
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@ -88,7 +88,10 @@ static struct io_uring_sqe *get_sqe(AioContext *ctx)
} }
/* No free sqes left, submit pending sqes first */ /* No free sqes left, submit pending sqes first */
ret = io_uring_submit(ring); do {
ret = io_uring_submit(ring);
} while (ret == -EINTR);
assert(ret > 1); assert(ret > 1);
sqe = io_uring_get_sqe(ring); sqe = io_uring_get_sqe(ring);
assert(sqe); assert(sqe);
@ -282,7 +285,10 @@ static int fdmon_io_uring_wait(AioContext *ctx, AioHandlerList *ready_list,
fill_sq_ring(ctx); fill_sq_ring(ctx);
ret = io_uring_submit_and_wait(&ctx->fdmon_io_uring, wait_nr); do {
ret = io_uring_submit_and_wait(&ctx->fdmon_io_uring, wait_nr);
} while (ret == -EINTR);
assert(ret >= 0); assert(ret >= 0);
return process_cq_ring(ctx, ready_list); return process_cq_ring(ctx, ready_list);