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author | Emanuele Giuseppe Esposito <eesposit@redhat.com> | 2023-09-29 16:51:40 +0200 |
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committer | Kevin Wolf <kwolf@redhat.com> | 2023-10-12 16:31:33 +0200 |
commit | d05ab380db649d882396653f9830b67d84bffbe1 (patch) | |
tree | b52f78b422f88e78caba4fde57d8a425519cd295 /block.c | |
parent | 2b3912f1350971fbc2c04d986a1d0c60ae757c78 (diff) | |
download | qemu-d05ab380db649d882396653f9830b67d84bffbe1.zip qemu-d05ab380db649d882396653f9830b67d84bffbe1.tar.gz qemu-d05ab380db649d882396653f9830b67d84bffbe1.tar.bz2 |
block: Mark drain related functions GRAPH_RDLOCK
Draining recursively traverses the graph, therefore we need to make sure
that also such accesses to the graph are protected by the graph rdlock.
There are 3 different drain callers to consider:
1. drain in the main loop: no issue at all, rdlock is nop.
2. drain in an iothread: rdlock only works in main loop or coroutines,
so disallow it.
3. drain in a coroutine (regardless of AioContext): the drain mechanism
takes care of scheduling a BH in the bs->aio_context that will
then take care of perform the actual draining. This is wrong,
because as pointed in (2) if bs->aio_context is an iothread then
rdlock won't work. Therefore change bdrv_co_yield_to_drain to
schedule the BH in the main loop.
Caller (2) also implies that we need to modify test-bdrv-drain.c to
disallow draining in the iothreads.
For some places, we know that they will hold the lock, but we don't have
the GRAPH_RDLOCK annotations yet. In this case, add assume_graph_lock()
with a FIXME comment. These places will be removed once everything is
properly annotated.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20230929145157.45443-6-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'block.c')
-rw-r--r-- | block.c | 6 |
1 files changed, 3 insertions, 3 deletions
@@ -1192,19 +1192,19 @@ static char *bdrv_child_get_parent_desc(BdrvChild *c) return g_strdup_printf("node '%s'", bdrv_get_node_name(parent)); } -static void bdrv_child_cb_drained_begin(BdrvChild *child) +static void GRAPH_RDLOCK bdrv_child_cb_drained_begin(BdrvChild *child) { BlockDriverState *bs = child->opaque; bdrv_do_drained_begin_quiesce(bs, NULL); } -static bool bdrv_child_cb_drained_poll(BdrvChild *child) +static bool GRAPH_RDLOCK bdrv_child_cb_drained_poll(BdrvChild *child) { BlockDriverState *bs = child->opaque; return bdrv_drain_poll(bs, NULL, false); } -static void bdrv_child_cb_drained_end(BdrvChild *child) +static void GRAPH_RDLOCK bdrv_child_cb_drained_end(BdrvChild *child) { BlockDriverState *bs = child->opaque; bdrv_drained_end(bs); |