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Tue, 10 Sep 2019 13:56:50 +0000 (UTC) Received: from dresden.str.redhat.com (ovpn-117-90.ams2.redhat.com [10.36.117.90]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8193C5D6B2; Tue, 10 Sep 2019 13:56:43 +0000 (UTC) To: Sergio Lopez , qemu-block@nongnu.org References: <20190910133611.149421-1-slp@redhat.com> From: Max Reitz Openpgp: preference=signencrypt Autocrypt: addr=mreitz@redhat.com; prefer-encrypt=mutual; keydata= mQENBFXOJlcBCADEyyhOTsoa/2ujoTRAJj4MKA21dkxxELVj3cuILpLTmtachWj7QW+TVG8U /PsMCFbpwsQR7oEy8eHHZwuGQsNpEtNC2G/L8Yka0BIBzv7dEgrPzIu+W3anZXQW4702+uES U29G8TP/NGfXRRHGlbBIH9KNUnOSUD2vRtpOLXkWsV5CN6vQFYgQfFvmp5ZpPeUe6xNplu8V mcTw8OSEDW/ZnxJc8TekCKZSpdzYoxfzjm7xGmZqB18VFwgJZlIibt1HE0EB4w5GsD7x5ekh awIe3RwoZgZDLQMdOitJ1tUc8aqaxvgA4tz6J6st8D8pS//m1gAoYJWGwwIVj1DjTYLtABEB AAG0HU1heCBSZWl0eiA8bXJlaXR6QHJlZGhhdC5jb20+iQFTBBMBCAA9AhsDBQkSzAMABQsJ CAcCBhUICQoLAgQWAgMBAh4BAheABQJVzie5FRhoa3A6Ly9rZXlzLmdudXBnLm5ldAAKCRD0 B9sAYdXPQDcIB/9uNkbYEex1rHKz3mr12uxYMwLOOFY9fstP5aoVJQ1nWQVB6m2cfKGdcRe1 2/nFaHSNAzT0NnKz2MjhZVmcrpyd2Gp2QyISCfb1FbT82GMtXFj1wiHmPb3CixYmWGQUUh+I AvUqsevLA+WihgBUyaJq/vuDVM1/K9Un+w+Tz5vpeMidlIsTYhcsMhn0L9wlCjoucljvbDy/ 8C9L2DUdgi3XTa0ORKeflUhdL4gucWoAMrKX2nmPjBMKLgU7WLBc8AtV+84b9OWFML6NEyo4 4cP7cM/07VlJK53pqNg5cHtnWwjHcbpGkQvx6RUx6F1My3y52vM24rNUA3+ligVEgPYBuQEN BFXOJlcBCADAmcVUNTWT6yLWQHvxZ0o47KCP8OcLqD+67T0RCe6d0LP8GsWtrJdeDIQk+T+F xO7DolQPS6iQ6Ak2/lJaPX8L0BkEAiMuLCKFU6Bn3lFOkrQeKp3u05wCSV1iKnhg0UPji9V2 W5eNfy8F4ZQHpeGUGy+liGXlxqkeRVhLyevUqfU0WgNqAJpfhHSGpBgihUupmyUg7lfUPeRM DzAN1pIqoFuxnN+BRHdAecpsLcbR8sQddXmDg9BpSKozO/JyBmaS1RlquI8HERQoe6EynJhd 64aICHDfj61rp+/0jTIcevxIIAzW70IadoS/y3DVIkuhncgDBvGbF3aBtjrJVP+5ABEBAAGJ ASUEGAEIAA8FAlXOJlcCGwwFCRLMAwAACgkQ9AfbAGHVz0CbFwf9F/PXxQR9i4N0iipISYjU sxVdjJOM2TMut+ZZcQ6NSMvhZ0ogQxJ+iEQ5OjnIputKvPVd5U7WRh+4lF1lB/NQGrGZQ1ic alkj6ocscQyFwfib+xIe9w8TG1CVGkII7+TbS5pXHRxZH1niaRpoi/hYtgzkuOPp35jJyqT/ /ELbqQTDAWcqtJhzxKLE/ugcOMK520dJDeb6x2xVES+S5LXby0D4juZlvUj+1fwZu+7Io5+B bkhSVPb/QdOVTpnz7zWNyNw+OONo1aBUKkhq2UIByYXgORPFnbfMY7QWHcjpBVw9MgC4tGeF R4bv+1nAMMxKmb5VvQCExr0eFhJUAHAhVg== Message-ID: Date: Tue, 10 Sep 2019 15:56:42 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190910133611.149421-1-slp@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="DP21KtyH7XZPNZBdy1raefn8R7pyvWlL0" X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Tue, 10 Sep 2019 13:56:50 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH v2] blockjob: update nodes head while removing all bdrv 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, jsnow@redhat.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --DP21KtyH7XZPNZBdy1raefn8R7pyvWlL0 Content-Type: multipart/mixed; boundary="ExK8cqMuSUBtTAjSUZSvIjXCZvC68qzQE"; protected-headers="v1" From: Max Reitz To: Sergio Lopez , qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, kwolf@redhat.com, jsnow@redhat.com Message-ID: Subject: Re: [PATCH v2] blockjob: update nodes head while removing all bdrv References: <20190910133611.149421-1-slp@redhat.com> In-Reply-To: <20190910133611.149421-1-slp@redhat.com> --ExK8cqMuSUBtTAjSUZSvIjXCZvC68qzQE Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 10.09.19 15:36, Sergio Lopez wrote: > block_job_remove_all_bdrv() iterates through job->nodes, calling > bdrv_root_unref_child() for each entry. The call to the latter may > reach child_job_[can_]set_aio_ctx(), which will also attempt to > traverse job->nodes, potentially finding entries that where freed > on previous iterations. >=20 > To avoid this situation, update job->nodes head on each iteration to > ensure that already freed entries are no longer linked to the list. >=20 > RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=3D1746631 > Signed-off-by: Sergio Lopez > --- > Changelog >=20 > v2: > - Avoid leaking job->nodes (thanks Max Reitz) > --- > blockjob.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > --- > diff --git a/blockjob.c b/blockjob.c > index 6e32d1a0c0..ffda6dd1e4 100644 > --- a/blockjob.c > +++ b/blockjob.c > @@ -187,13 +187,21 @@ static const BdrvChildRole child_job =3D { > =20 > void block_job_remove_all_bdrv(BlockJob *job) > { > - GSList *l; > + GSList *l, *orig_nodes; > + > + orig_nodes =3D job->nodes; > for (l =3D job->nodes; l; l =3D l->next) { > BdrvChild *c =3D l->data; > bdrv_op_unblock_all(c->bs, job->blocker); > bdrv_root_unref_child(c); > + /* > + * The call above may reach child_job_[can_]set_aio_ctx(), whi= ch will > + * also traverse job->nodes, so update the head here to make s= ure it > + * doesn't attempt to process an already freed BdrvChild. > + */ > + job->nodes =3D l->next; > } > - g_slist_free(job->nodes); > + g_slist_free(orig_nodes); > job->nodes =3D NULL; Hm, this assignment is now a no-op. I think I=E2=80=99d just rewrite the whole function in the following fash= ion: orig_nodes =3D job->nodes; while (job->nodes) { BdrvChild *c =3D job->nodes->data; [...] job->nodes =3D job->nodes->next; } g_slist_free(orig_nodes); What do you think? > } > =20 >=20 --ExK8cqMuSUBtTAjSUZSvIjXCZvC68qzQE-- --DP21KtyH7XZPNZBdy1raefn8R7pyvWlL0 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEkb62CjDbPohX0Rgp9AfbAGHVz0AFAl13q5oACgkQ9AfbAGHV z0DRGAf/SaVK6IpDV36rSKUdlo/FKJPxOMK73pZYfsm0hYdSW0KFS/nXNhvA1/A5 QGDkx0z4jkvdQHHsSFvgHm5EjnOZ33w4BtkpKldIGHJtnMeg+f+OrvEY0He7GO/C NhsQKuEtaqhHZKYLuIAcNonZaKI7nrk1a3Z4R/oI2TKxw7Om2e6Yz8E/iY+Y3W7F oLXgkxIXTLHNs2MSdBiiD07nCSe3PJwFt/FKhv9oDa15jwGAjQ21zLbxgpJe1Wyu FvJIaIxz0op5geHd5ovlsU24HceWTwWSY8lcpnlA9xubX/80xMYRJ5WKCYWmxcpp F9EznmBlZlDUL1qpg+3dxodYeOjUDQ== =ETx6 -----END PGP SIGNATURE----- --DP21KtyH7XZPNZBdy1raefn8R7pyvWlL0--