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, 10 insertions, 4 deletions

diff --git a/blockdev.c b/blockdev.c
index 2e941e2979..46090bb0aa 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -150,12 +150,15 @@ void blockdev_mark_auto_del(BlockBackend *blk)
         return;
     }
 
-    for (job = block_job_next(NULL); job; job = block_job_next(job)) {
+    JOB_LOCK_GUARD();
+
+    for (job = block_job_next_locked(NULL); job;
+         job = block_job_next_locked(job)) {
         if (block_job_has_bdrv(job, blk_bs(blk))) {
             AioContext *aio_context = job->job.aio_context;
             aio_context_acquire(aio_context);
 
-            job_cancel(&job->job, false);
+            job_cancel_locked(&job->job, false);
 
             aio_context_release(aio_context);
         }
@@ -3756,7 +3759,10 @@ BlockJobInfoList *qmp_query_block_jobs(Error **errp)
     BlockJobInfoList *head = NULL, **tail = &head;
     BlockJob *job;
 
-    for (job = block_job_next(NULL); job; job = block_job_next(job)) {
+    JOB_LOCK_GUARD();
+
+    for (job = block_job_next_locked(NULL); job;
+         job = block_job_next_locked(job)) {
         BlockJobInfo *value;
         AioContext *aio_context;
 
@@ -3765,7 +3771,7 @@ BlockJobInfoList *qmp_query_block_jobs(Error **errp)
         }
         aio_context = block_job_get_aio_context(job);
         aio_context_acquire(aio_context);
-        value = block_job_query(job, errp);
+        value = block_job_query_locked(job, errp);
         aio_context_release(aio_context);
         if (!value) {
             qapi_free_BlockJobInfoList(head);