Max Reitz <mre...@redhat.com> writes: > From: Sergio Lopez <s...@redhat.com> > > 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. > > To avoid this situation, update job->nodes head on each iteration to > ensure that already freed entries are no longer linked to the list. > > RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=1746631 > Signed-off-by: Sergio Lopez <s...@redhat.com> > Cc: qemu-sta...@nongnu.org > Signed-off-by: Max Reitz <mre...@redhat.com> > --- > v3: > - Rewrote the loop to make the whole function a bit simpler > (Also, remove the node from the job->nodes list before unref'ing it, > just to be extra-safe) > --- > blockjob.c | 17 +++++++++++++---- > 1 file changed, 13 insertions(+), 4 deletions(-) > > diff --git a/blockjob.c b/blockjob.c > index 2abed0f551..c6e20e2fcd 100644 > --- a/blockjob.c > +++ b/blockjob.c > @@ -175,14 +175,23 @@ static const BdrvChildRole child_job = { > > void block_job_remove_all_bdrv(BlockJob *job) > { > - GSList *l; > - for (l = job->nodes; l; l = l->next) { > + /* > + * bdrv_root_unref_child() may reach child_job_[can_]set_aio_ctx(), > + * which will also traverse job->nodes, so consume the list one by > + * one to make sure that such a concurrent access does not attempt > + * to process an already freed BdrvChild. > + */ > + while (job->nodes) { > + GSList *l = job->nodes; > BdrvChild *c = l->data; > + > + job->nodes = l->next; > + > bdrv_op_unblock_all(c->bs, job->blocker); > bdrv_root_unref_child(c); > + > + g_slist_free_1(l); > } > - g_slist_free(job->nodes); > - job->nodes = NULL; > } > > bool block_job_has_bdrv(BlockJob *job, BlockDriverState *bs)
Reviewed-by: Sergio Lopez <s...@redhat.com>
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