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bh=6NIeb6J2hXZMS6IPTLtCJ3U06o+IQckAJ6Imw5hiW/c=; b=VLQ5j0jrvUQcKD5hSzuDdouVTlfuz+nJHAczxfZ6he4tZGOfsmcPV+Dwu98dlZt20lS35D FnpoGoPRvdS7KAFGBeBh2x9IpmA8GHCDW6PauRx3/BfB6mr6eKW4pdpGqCPp3UcejWFGhv M6LVAoWZfRXhTQyK5glejE4QD0/S5CQ= X-MC-Unique: m39a5ieEOwCmLoW2U8xhvw-1 From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, richard.henderson@linaro.org, qemu-devel@nongnu.org Subject: [PULL 04/23] block: Fix AioContext locking in bdrv_open_child() Date: Wed, 28 Jun 2023 16:15:07 +0200 Message-ID: <20230628141526.293104-5-kwolf@redhat.com> In-Reply-To: <20230628141526.293104-1-kwolf@redhat.com> References: <20230628141526.293104-1-kwolf@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1687961785541100003 Content-Type: text/plain; charset="utf-8" bdrv_attach_child() requires that the caller holds the AioContext lock for the new child node. Take it in bdrv_open_child() and document that the caller must not hold any AioContext apart from the main AioContext. Signed-off-by: Kevin Wolf Message-ID: <20230605085711.21261-5-kwolf@redhat.com> Reviewed-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf --- block.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/block.c b/block.c index 0637265c26..213a09643d 100644 --- a/block.c +++ b/block.c @@ -3654,6 +3654,7 @@ done: * * The BlockdevRef will be removed from the options QDict. * + * The caller must hold the lock of the main AioContext and no other AioCo= ntext. * @parent can move to a different AioContext in this function. Callers mu= st * make sure that their AioContext locking is still correct after this. */ @@ -3665,6 +3666,8 @@ BdrvChild *bdrv_open_child(const char *filename, bool allow_none, Error **errp) { BlockDriverState *bs; + BdrvChild *child; + AioContext *ctx; =20 GLOBAL_STATE_CODE(); =20 @@ -3674,13 +3677,19 @@ BdrvChild *bdrv_open_child(const char *filename, return NULL; } =20 - return bdrv_attach_child(parent, bs, bdref_key, child_class, child_rol= e, - errp); + ctx =3D bdrv_get_aio_context(bs); + aio_context_acquire(ctx); + child =3D bdrv_attach_child(parent, bs, bdref_key, child_class, child_= role, + errp); + aio_context_release(ctx); + + return child; } =20 /* * Wrapper on bdrv_open_child() for most popular case: open primary child = of bs. * + * The caller must hold the lock of the main AioContext and no other AioCo= ntext. * @parent can move to a different AioContext in this function. Callers mu= st * make sure that their AioContext locking is still correct after this. */ --=20 2.41.0