jobs: group together API calls under the same job lock

Now that the API offers also _locked() functions, take advantage
of it and give also the caller control to take the lock and call
_locked functions.

This makes sense especially when we have for loops, because it
makes no sense to have:

for(job = job_next(); ...)

where each job_next() takes the lock internally.
Instead we want

JOB_LOCK_GUARD();
for(job = job_next_locked(); ...)

In addition, protect also direct field accesses, by either creating a
new critical section or widening the existing ones.

Note: at this stage, job_{lock/unlock} and job lock guard macros
are *nop*.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-Id: <20220926093214.506243-12-eesposit@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 22 insertions, 13 deletions

diff --git a/blockjob.c b/blockjob.c
index 0d59aba439..96fb9d9f73 100644
--- a/blockjob.c
+++ b/blockjob.c
@@ -111,8 +111,10 @@ static bool child_job_drained_poll(BdrvChild *c)
     /* An inactive or completed job doesn't have any pending requests. Jobs
      * with !job->busy are either already paused or have a pause point after
      * being reentered, so no job driver code will run before they pause. */
-    if (!job->busy || job_is_completed(job)) {
-        return false;
+    WITH_JOB_LOCK_GUARD() {
+        if (!job->busy || job_is_completed_locked(job)) {
+            return false;
+        }
     }
 
     /* Otherwise, assume that it isn't fully stopped yet, but allow the job to
@@ -475,13 +477,15 @@ void *block_job_create(const char *job_id, const BlockJobDriver *driver,
     job->ready_notifier.notify = block_job_event_ready;
     job->idle_notifier.notify = block_job_on_idle;
 
-    notifier_list_add(&job->job.on_finalize_cancelled,
-                      &job->finalize_cancelled_notifier);
-    notifier_list_add(&job->job.on_finalize_completed,
-                      &job->finalize_completed_notifier);
-    notifier_list_add(&job->job.on_pending, &job->pending_notifier);
-    notifier_list_add(&job->job.on_ready, &job->ready_notifier);
-    notifier_list_add(&job->job.on_idle, &job->idle_notifier);
+    WITH_JOB_LOCK_GUARD() {
+        notifier_list_add(&job->job.on_finalize_cancelled,
+                          &job->finalize_cancelled_notifier);
+        notifier_list_add(&job->job.on_finalize_completed,
+                          &job->finalize_completed_notifier);
+        notifier_list_add(&job->job.on_pending, &job->pending_notifier);
+        notifier_list_add(&job->job.on_ready, &job->ready_notifier);
+        notifier_list_add(&job->job.on_idle, &job->idle_notifier);
+    }
 
     error_setg(&job->blocker, "block device is in use by block job: %s",
                job_type_str(&job->job));
@@ -558,10 +562,15 @@ BlockErrorAction block_job_error_action(BlockJob *job, BlockdevOnError on_err,
                                         action);
     }
     if (action == BLOCK_ERROR_ACTION_STOP) {
-        if (!job->job.user_paused) {
-            job_pause(&job->job);
-            /* make the pause user visible, which will be resumed from QMP. */
-            job->job.user_paused = true;
+        WITH_JOB_LOCK_GUARD() {
+            if (!job->job.user_paused) {
+                job_pause_locked(&job->job);
+                /*
+                 * make the pause user visible, which will be
+                 * resumed from QMP.
+                 */
+                job->job.user_paused = true;
+            }
         }
         block_job_iostatus_set_err(job, error);
     }