Re: [PATCH for-5.0] aio-posix: signal-proof fdmon-io_uring

[Stefano Garzarella]

On Wed, Apr 08, 2020 at 10:11:39AM +0100, Stefan Hajnoczi wrote:
> 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 <stefa...@redhat.com>
> ---
>  util/fdmon-io_uring.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)

The patch LGTM:

Reviewed-by: Stefano Garzarella <sgarz...@redhat.com>

Not related to this patch, looking at block/io_uring.c, should we retry
if the io_uring_submit() fails with EINTR?

I mean something like this:

diff --git a/block/io_uring.c b/block/io_uring.c
index a3142ca989..9765681f7c 100644
--- a/block/io_uring.c
+++ b/block/io_uring.c
@@ -231,7 +231,7 @@ static int ioq_submit(LuringState *s)
         trace_luring_io_uring_submit(s, ret);
         /* Prevent infinite loop if submission is refused */
         if (ret <= 0) {
-            if (ret == -EAGAIN) {
+            if (ret == -EAGAIN || ret == -EINTR) {
                 continue;
             }
             break;

Thanks,
Stefano