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Location : parse_addr6(), p0f-client.c:67 X-Received-From: 2a00:1450:4864:20::342 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: kwolf@redhat.com, fam@euphon.net, qemu-block@nongnu.org, qemu-devel@nongnu.org, mreitz@redhat.com, Stefan Hajnoczi , den@openvz.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --EemXnrF2ob+xzFeB Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Apr 22, 2020 at 04:47:07PM +0300, Vladimir Sementsov-Ogievskiy wrot= e: > 20.04.2020 19:22, Stefan Hajnoczi wrote: > > On Wed, Apr 08, 2020 at 12:30:47PM +0300, Vladimir Sementsov-Ogievskiy = wrote: > > > It's safer to expand in_flight request to start before enter to > >=20 > > Please explain what exeactly "safer" means. If I understand correctly > > this is just a refactoring and does not fix bugs that have been hit in > > the real world. > >=20 > > Is this just a generate attempt to avoid accidentally performing > > operations that need to happen as part of the request after the dec > > call? >=20 > Consider write. >=20 > It's possible, that qemu_coroutine_enter only schedules execution, assume= such case. > Then we may possibly have the following: >=20 > 1. Somehow check that we are not in drained section in outer code >=20 > 2. call bdrv_pwritev(), assuming that it will increse in_flight, which wi= ll protect us from starting drained section >=20 > 3. it calls bdrv_prwv_co -> bdrv_coroutine_enter (not yet increased in_fl= ight) >=20 > 4. assume coroutine not yet actually entered, only scheduled, and we go t= o some code, which starts drained section (as in_flight is zero) >=20 > 5. scheduled coroutine starts, and blindly increases in_flight, and we ar= e in drained section with in_flight request. >=20 > The series does the same thing for block/io.c like Kevin's "block: Fix bl= k->in_flight during blk_wait_while_drained()" for blk layer. Please include this in the commit description. Thanks! Stefan --EemXnrF2ob+xzFeB Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAl6ga48ACgkQnKSrs4Gr c8gqwQf+N51Jvfl6eeRMeFLHsXfB+G/Tq4yFcN2qZlfq+Ztzj2wggtKYpudMbsmC evyTErRCKS1/DpvmmJMwjAFyX2A/DnujVhefrY3ELjZnTUzpNAYO3IMHvstPegGw 6NoeRMILfFs0zYU3hn1ta5miZ0K1YvniUGMlbmQGf4E3VN9PczaQY/hQsIfNMp+X ZcHVAGNDc4ZWblUz5G7ZVpgULdh4hR9n700ofYe+kSOSzvA3F82EjGE/DdeTE6Y/ DFsS6nAo9Kf7bgCzjtK3bZpXAgQkpm/3sPr5nMwiOXc8LZANreRZfJ2H43EXdnZ1 fHCW9IvvEYgPNZnZsdZym5Lgc+9+tg== =sqNn -----END PGP SIGNATURE----- --EemXnrF2ob+xzFeB--