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authorFam Zheng <famz@redhat.com>2018-08-24 10:43:42 +0800
committerKevin Wolf <kwolf@redhat.com>2018-09-25 15:50:15 +0200
commit49880165a44f26dc84651858750facdee31f2513 (patch)
tree3618fd2603a21d63298456f8b1d679d7ed736560
parent6808ae0417131f8dbe7b051256dff7a16634dc1d (diff)
job: Fix nested aio_poll() hanging in job_txn_apply
All callers have acquired ctx already. Doing that again results in aio_poll() hang. This fixes the problem that a BDRV_POLL_WHILE() in the callback cannot make progress because ctx is recursively locked, for example, when drive-backup finishes. There are two callers of job_finalize(): fam@lemon:~/work/qemu [master]$ git grep -w -A1 '^\s*job_finalize' blockdev.c: job_finalize(&job->job, errp); blockdev.c- aio_context_release(aio_context); -- job-qmp.c: job_finalize(job, errp); job-qmp.c- aio_context_release(aio_context); -- tests/test-blockjob.c: job_finalize(&job->job, &error_abort); tests/test-blockjob.c- assert(job->job.status == JOB_STATUS_CONCLUDED); Ignoring the test, it's easy to see both callers to job_finalize (and job_do_finalize) have acquired the context. Cc: qemu-stable@nongnu.org Reported-by: Gu Nini <ngu@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Fam Zheng <famz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
-rw-r--r--job.c18
1 files changed, 5 insertions, 13 deletions
diff --git a/job.c b/job.c
index 192f168423..3dd31a5f8e 100644
--- a/job.c
+++ b/job.c
@@ -136,21 +136,13 @@ static void job_txn_del_job(Job *job)
}
}
-static int job_txn_apply(JobTxn *txn, int fn(Job *), bool lock)
+static int job_txn_apply(JobTxn *txn, int fn(Job *))
{
- AioContext *ctx;
Job *job, *next;
int rc = 0;
QLIST_FOREACH_SAFE(job, &txn->jobs, txn_list, next) {
- if (lock) {
- ctx = job->aio_context;
- aio_context_acquire(ctx);
- }
rc = fn(job);
- if (lock) {
- aio_context_release(ctx);
- }
if (rc) {
break;
}
@@ -780,11 +772,11 @@ static void job_do_finalize(Job *job)
assert(job && job->txn);
/* prepare the transaction to complete */
- rc = job_txn_apply(job->txn, job_prepare, true);
+ rc = job_txn_apply(job->txn, job_prepare);
if (rc) {
job_completed_txn_abort(job);
} else {
- job_txn_apply(job->txn, job_finalize_single, true);
+ job_txn_apply(job->txn, job_finalize_single);
}
}
@@ -830,10 +822,10 @@ static void job_completed_txn_success(Job *job)
assert(other_job->ret == 0);
}
- job_txn_apply(txn, job_transition_to_pending, false);
+ job_txn_apply(txn, job_transition_to_pending);
/* If no jobs need manual finalization, automatically do so */
- if (job_txn_apply(txn, job_needs_finalize, false) == 0) {
+ if (job_txn_apply(txn, job_needs_finalize) == 0) {
job_do_finalize(job);
}
}