| Message ID | 20180824024342.749-1-famz@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] job: Fix nested aio_poll() hanging in job_txn_apply | expand |
On Fri, 08/24 10:43, Fam Zheng wrote: > 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> Ping?
Am 24.08.2018 um 04:43 hat Fam Zheng geschrieben: > 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> Thanks, applied to the block branch. Kevin
diff --git a/job.c b/job.c index e36ebaafd8..a3bec7fb22 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; } @@ -807,11 +799,11 @@ 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); } } @@ -857,10 +849,10 @@ 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); } }
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> --- v2: Add Eric's r-b and some more details in commit message. --- job.c | 18 +++++------------- 1 file changed, 5 insertions(+), 13 deletions(-)