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[83.42.57.116]) by smtp.gmail.com with ESMTPSA id ch5sm457694ejb.60.2020.04.08.04.47.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 08 Apr 2020 04:47:45 -0700 (PDT) Subject: Re: [PATCH for-5.0] aio-posix: signal-proof fdmon-io_uring To: Stefan Hajnoczi , qemu-devel@nongnu.org References: <20200408091139.273851-1-stefanha@redhat.com> From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= Message-ID: Date: Wed, 8 Apr 2020 13:47:43 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200408091139.273851-1-stefanha@redhat.com> Content-Language: en-US X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Fam Zheng , Paolo Bonzini , Julia Suvorova , qemu-block@nongnu.org, sgarzare@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 4/8/20 11:11 AM, Stefan Hajnoczi wrote: > The io_uring_enter(2) syscall returns with errno=3DEINTR when interrupted > by a signal. Retry the syscall in this case. >=20 > 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. This is how io_uring_enter() is documented indeed (no EINTR). Reviewed-by: Philippe Mathieu-Daud=C3=A9 > Let's check for -EINTR around both APIs. >=20 > Note that the liburing APIs have -errno return values. >=20 > Signed-off-by: Stefan Hajnoczi > --- > util/fdmon-io_uring.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) >=20 > diff --git a/util/fdmon-io_uring.c b/util/fdmon-io_uring.c > index b4d6109f20..d5a80ed6fb 100644 > --- a/util/fdmon-io_uring.c > +++ b/util/fdmon-io_uring.c > @@ -88,7 +88,10 @@ static struct io_uring_sqe *get_sqe(AioContext *ctx) > } > =20 > /* No free sqes left, submit pending sqes first */ > - ret =3D io_uring_submit(ring); > + do { > + ret =3D io_uring_submit(ring); > + } while (ret =3D=3D -EINTR); > + > assert(ret > 1); > sqe =3D io_uring_get_sqe(ring); > assert(sqe); > @@ -282,7 +285,10 @@ static int fdmon_io_uring_wait(AioContext *ctx, AioH= andlerList *ready_list, > =20 > fill_sq_ring(ctx); > =20 > - ret =3D io_uring_submit_and_wait(&ctx->fdmon_io_uring, wait_nr); > + do { > + ret =3D io_uring_submit_and_wait(&ctx->fdmon_io_uring, wait_nr); > + } while (ret =3D=3D -EINTR); > + > assert(ret >=3D 0); > =20 > return process_cq_ring(ctx, ready_list); >=20