[RFC PATCH v2 13/14] jobs: add job lock in find_* functions

[Emanuele Giuseppe Esposito <eesposit@redhat.com>]

Both blockdev.c and job-qmp.c have TOC/TOU conditions, because
they first search for the job and then perform an action on it.
Therefore, we need to do the search + action under the same
job mutex critical section.

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

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
---
 blockdev.c | 9 +++++++++
 job-qmp.c  | 8 ++++++++
 2 files changed, 17 insertions(+)

diff --git a/blockdev.c b/blockdev.c
index c5a835d9ed..0bd79757fc 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3327,12 +3327,14 @@ static BlockJob *find_block_job(const char *id, AioContext **aio_context,
     assert(id != NULL);
 
     *aio_context = NULL;
+    job_lock();
 
     job = block_job_get(id);
 
     if (!job) {
         error_set(errp, ERROR_CLASS_DEVICE_NOT_ACTIVE,
                   "Block job '%s' not found", id);
+        job_unlock();
         return NULL;
     }
 
@@ -3353,6 +3355,7 @@ void qmp_block_job_set_speed(const char *device, int64_t speed, Error **errp)
 
     block_job_set_speed(job, speed, errp);
     aio_context_release(aio_context);
+    job_unlock();
 }
 
 void qmp_block_job_cancel(const char *device,
@@ -3379,6 +3382,7 @@ void qmp_block_job_cancel(const char *device,
     job_user_cancel(&job->job, force, errp);
 out:
     aio_context_release(aio_context);
+    job_unlock();
 }
 
 void qmp_block_job_pause(const char *device, Error **errp)
@@ -3393,6 +3397,7 @@ void qmp_block_job_pause(const char *device, Error **errp)
     trace_qmp_block_job_pause(job);
     job_user_pause(&job->job, errp);
     aio_context_release(aio_context);
+    job_unlock();
 }
 
 void qmp_block_job_resume(const char *device, Error **errp)
@@ -3407,6 +3412,7 @@ void qmp_block_job_resume(const char *device, Error **errp)
     trace_qmp_block_job_resume(job);
     job_user_resume(&job->job, errp);
     aio_context_release(aio_context);
+    job_unlock();
 }
 
 void qmp_block_job_complete(const char *device, Error **errp)
@@ -3421,6 +3427,7 @@ void qmp_block_job_complete(const char *device, Error **errp)
     trace_qmp_block_job_complete(job);
     job_complete(&job->job, errp);
     aio_context_release(aio_context);
+    job_unlock();
 }
 
 void qmp_block_job_finalize(const char *id, Error **errp)
@@ -3444,6 +3451,7 @@ void qmp_block_job_finalize(const char *id, Error **errp)
     aio_context = blk_get_aio_context(job->blk);
     job_unref(&job->job);
     aio_context_release(aio_context);
+    job_unlock();
 }
 
 void qmp_block_job_dismiss(const char *id, Error **errp)
@@ -3460,6 +3468,7 @@ void qmp_block_job_dismiss(const char *id, Error **errp)
     job = &bjob->job;
     job_dismiss(&job, errp);
     aio_context_release(aio_context);
+    job_unlock();
 }
 
 void qmp_change_backing_file(const char *device,
diff --git a/job-qmp.c b/job-qmp.c
index a355dc2954..8f07c51db8 100644
--- a/job-qmp.c
+++ b/job-qmp.c
@@ -35,10 +35,12 @@ static Job *find_job(const char *id, AioContext **aio_context, Error **errp)
     Job *job;
 
     *aio_context = NULL;
+    job_lock();
 
     job = job_get(id);
     if (!job) {
         error_setg(errp, "Job not found");
+        job_unlock();
         return NULL;
     }
 
@@ -60,6 +62,7 @@ void qmp_job_cancel(const char *id, Error **errp)
     trace_qmp_job_cancel(job);
     job_user_cancel(job, true, errp);
     aio_context_release(aio_context);
+    job_unlock();
 }
 
 void qmp_job_pause(const char *id, Error **errp)
@@ -74,6 +77,7 @@ void qmp_job_pause(const char *id, Error **errp)
     trace_qmp_job_pause(job);
     job_user_pause(job, errp);
     aio_context_release(aio_context);
+    job_unlock();
 }
 
 void qmp_job_resume(const char *id, Error **errp)
@@ -88,6 +92,7 @@ void qmp_job_resume(const char *id, Error **errp)
     trace_qmp_job_resume(job);
     job_user_resume(job, errp);
     aio_context_release(aio_context);
+    job_unlock();
 }
 
 void qmp_job_complete(const char *id, Error **errp)
@@ -102,6 +107,7 @@ void qmp_job_complete(const char *id, Error **errp)
     trace_qmp_job_complete(job);
     job_complete(job, errp);
     aio_context_release(aio_context);
+    job_unlock();
 }
 
 void qmp_job_finalize(const char *id, Error **errp)
@@ -125,6 +131,7 @@ void qmp_job_finalize(const char *id, Error **errp)
     aio_context = job->aio_context;
     job_unref(job);
     aio_context_release(aio_context);
+    job_unlock();
 }
 
 void qmp_job_dismiss(const char *id, Error **errp)
@@ -139,6 +146,7 @@ void qmp_job_dismiss(const char *id, Error **errp)
     trace_qmp_job_dismiss(job);
     job_dismiss(&job, errp);
     aio_context_release(aio_context);
+    job_unlock();
 }
 
 static JobInfo *job_query_single(Job *job, Error **errp)
-- 
2.27.0