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From: Kevin Wolf <kwolf@redhat.com>
To: qemu-block@nongnu.org
Cc: kwolf@redhat.com, richard.henderson@linaro.org, qemu-devel@nongnu.org
Subject: [PULL 02/32] block: Clarify locking rules for bdrv_open(_inherit)()
Date: Tue, 30 May 2023 18:32:09 +0200	[thread overview]
Message-ID: <20230530163239.576632-3-kwolf@redhat.com> (raw)
In-Reply-To: <20230530163239.576632-1-kwolf@redhat.com>

These functions specify that the caller must hold the "@filename
AioContext lock". This doesn't make sense, file names don't have an
AioContext. New BlockDriverStates always start in the main AioContext,
so this is what we really need here.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230525124713.401149-3-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/block.c b/block.c
index a2f8d5a0c0..6ac47112fe 100644
--- a/block.c
+++ b/block.c
@@ -3810,9 +3810,7 @@ out:
  * should be opened. If specified, neither options nor a filename may be given,
  * nor can an existing BDS be reused (that is, *pbs has to be NULL).
  *
- * The caller must always hold @filename AioContext lock, because this
- * function eventually calls bdrv_refresh_total_sectors() which polls
- * when called from non-coroutine context.
+ * The caller must always hold the main AioContext lock.
  */
 static BlockDriverState * no_coroutine_fn
 bdrv_open_inherit(const char *filename, const char *reference, QDict *options,
@@ -4100,11 +4098,7 @@ close_and_fail:
     return NULL;
 }
 
-/*
- * The caller must always hold @filename AioContext lock, because this
- * function eventually calls bdrv_refresh_total_sectors() which polls
- * when called from non-coroutine context.
- */
+/* The caller must always hold the main AioContext lock. */
 BlockDriverState *bdrv_open(const char *filename, const char *reference,
                             QDict *options, int flags, Error **errp)
 {
-- 
2.40.1



  parent reply	other threads:[~2023-05-30 16:33 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-30 16:32 [PULL 00/32] Block layer patches Kevin Wolf
2023-05-30 16:32 ` [PULL 01/32] block-coroutine-wrapper: Take AioContext lock in no_co_wrappers Kevin Wolf
2023-05-30 16:32 ` Kevin Wolf [this message]
2023-05-30 16:32 ` [PULL 03/32] block: Take main AioContext lock when calling bdrv_open() Kevin Wolf
2023-05-30 16:32 ` [PULL 04/32] block-backend: Fix blk_new_open() for iothreads Kevin Wolf
2023-05-30 16:32 ` [PULL 05/32] mirror: Hold main AioContext lock for calling bdrv_open_backing_file() Kevin Wolf
2023-05-30 16:32 ` [PULL 06/32] qcow2: Fix open with 'file' in iothread Kevin Wolf
2023-05-30 16:32 ` [PULL 07/32] raw-format: " Kevin Wolf
2023-05-30 16:32 ` [PULL 08/32] copy-before-write: Fix open with child " Kevin Wolf
2023-05-30 16:32 ` [PULL 09/32] block: Take AioContext lock in bdrv_open_driver() Kevin Wolf
2023-05-30 16:32 ` [PULL 10/32] block: Fix AioContext locking in bdrv_insert_node() Kevin Wolf
2023-05-30 16:32 ` [PULL 11/32] iotests: Make verify_virtio_scsi_pci_or_ccw() public Kevin Wolf
2023-05-30 16:32 ` [PULL 12/32] iotests: Test blockdev-create in iothread Kevin Wolf
2023-05-30 16:32 ` [PULL 13/32] block-backend: split blk_do_set_aio_context() Kevin Wolf
2023-05-30 16:32 ` [PULL 14/32] hw/qdev: introduce qdev_is_realized() helper Kevin Wolf
2023-05-30 16:32 ` [PULL 15/32] virtio-scsi: avoid race between unplug and transport event Kevin Wolf
2023-05-30 16:32 ` [PULL 16/32] virtio-scsi: stop using aio_disable_external() during unplug Kevin Wolf
2023-05-30 16:32 ` [PULL 17/32] util/vhost-user-server: rename refcount to in_flight counter Kevin Wolf
2023-05-30 16:32 ` [PULL 18/32] block/export: wait for vhost-user-blk requests when draining Kevin Wolf
2023-05-30 16:32 ` [PULL 19/32] block/export: stop using is_external in vhost-user-blk server Kevin Wolf
2023-05-30 16:32 ` [PULL 20/32] hw/xen: do not use aio_set_fd_handler(is_external=true) in xen_xenstore Kevin Wolf
2023-05-30 16:32 ` [PULL 21/32] block: add blk_in_drain() API Kevin Wolf
2023-05-30 16:32 ` [PULL 22/32] block: drain from main loop thread in bdrv_co_yield_to_drain() Kevin Wolf
2023-05-30 16:32 ` [PULL 23/32] xen-block: implement BlockDevOps->drained_begin() Kevin Wolf
2023-05-30 16:32 ` [PULL 24/32] hw/xen: do not set is_external=true on evtchn fds Kevin Wolf
2023-05-30 16:32 ` [PULL 25/32] block/export: rewrite vduse-blk drain code Kevin Wolf
2023-05-30 16:32 ` [PULL 26/32] block/export: don't require AioContext lock around blk_exp_ref/unref() Kevin Wolf
2023-05-30 16:32 ` [PULL 27/32] block/fuse: do not set is_external=true on FUSE fd Kevin Wolf
2023-05-30 16:32 ` [PULL 28/32] virtio: make it possible to detach host notifier from any thread Kevin Wolf
2023-05-30 16:32 ` [PULL 29/32] virtio-blk: implement BlockDevOps->drained_begin() Kevin Wolf
2023-11-03 13:12   ` Fiona Ebner
2023-11-13 14:38     ` Fiona Ebner
2023-12-07 15:22     ` Fiona Ebner
2023-12-08  8:32       ` Kevin Wolf
2023-12-11 10:48         ` Fiona Ebner
2023-12-13 21:19           ` Stefan Hajnoczi
2023-05-30 16:32 ` [PULL 30/32] virtio-scsi: " Kevin Wolf
2023-05-30 16:32 ` [PULL 31/32] virtio: do not set is_external=true on host notifiers Kevin Wolf
2023-05-30 16:32 ` [PULL 32/32] aio: remove aio_disable_external() API Kevin Wolf
2023-05-30 18:33 ` [PULL 00/32] Block layer patches Richard Henderson

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