[PATCH v7 07/18] 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 | 46 +++++++++++++++++++++++++++++++++++-----------
 job-qmp.c  | 37 +++++++++++++++++++++++++++++--------
 2 files changed, 64 insertions(+), 19 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index b1099e678c..6f83783f10 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3311,9 +3311,13 @@ out:
     aio_context_release(aio_context);
 }
 
-/* Get a block job using its ID and acquire its AioContext */
-static BlockJob *find_block_job(const char *id, AioContext **aio_context,
-                                Error **errp)
+/*
+ * Get a block job using its ID and acquire its AioContext.
+ * Called with job_mutex held.
+ */
+static BlockJob *find_block_job_locked(const char *id,
+                                       AioContext **aio_context,
+                                       Error **errp)
 {
     BlockJob *job;
 
@@ -3322,7 +3326,6 @@ static BlockJob *find_block_job(const char *id, AioContext **aio_context,
     *aio_context = NULL;
 
     job = block_job_get(id);
-
     if (!job) {
         error_set(errp, ERROR_CLASS_DEVICE_NOT_ACTIVE,
                   "Block job '%s' not found", id);
@@ -3338,7 +3341,10 @@ static BlockJob *find_block_job(const char *id, AioContext **aio_context,
 void qmp_block_job_set_speed(const char *device, int64_t speed, Error **errp)
 {
     AioContext *aio_context;
-    BlockJob *job = find_block_job(device, &aio_context, errp);
+    BlockJob *job;
+
+    JOB_LOCK_GUARD();
+    job = find_block_job_locked(device, &aio_context, errp);
 
     if (!job) {
         return;
@@ -3352,7 +3358,10 @@ void qmp_block_job_cancel(const char *device,
                           bool has_force, bool force, Error **errp)
 {
     AioContext *aio_context;
-    BlockJob *job = find_block_job(device, &aio_context, errp);
+    BlockJob *job;
+
+    JOB_LOCK_GUARD();
+    job = find_block_job_locked(device, &aio_context, errp);
 
     if (!job) {
         return;
@@ -3377,7 +3386,10 @@ out:
 void qmp_block_job_pause(const char *device, Error **errp)
 {
     AioContext *aio_context;
-    BlockJob *job = find_block_job(device, &aio_context, errp);
+    BlockJob *job;
+
+    JOB_LOCK_GUARD();
+    job = find_block_job_locked(device, &aio_context, errp);
 
     if (!job) {
         return;
@@ -3391,7 +3403,10 @@ void qmp_block_job_pause(const char *device, Error **errp)
 void qmp_block_job_resume(const char *device, Error **errp)
 {
     AioContext *aio_context;
-    BlockJob *job = find_block_job(device, &aio_context, errp);
+    BlockJob *job;
+
+    JOB_LOCK_GUARD();
+    job = find_block_job_locked(device, &aio_context, errp);
 
     if (!job) {
         return;
@@ -3405,7 +3420,10 @@ void qmp_block_job_resume(const char *device, Error **errp)
 void qmp_block_job_complete(const char *device, Error **errp)
 {
     AioContext *aio_context;
-    BlockJob *job = find_block_job(device, &aio_context, errp);
+    BlockJob *job;
+
+    JOB_LOCK_GUARD();
+    job = find_block_job_locked(device, &aio_context, errp);
 
     if (!job) {
         return;
@@ -3419,7 +3437,10 @@ void qmp_block_job_complete(const char *device, Error **errp)
 void qmp_block_job_finalize(const char *id, Error **errp)
 {
     AioContext *aio_context;
-    BlockJob *job = find_block_job(id, &aio_context, errp);
+    BlockJob *job;
+
+    JOB_LOCK_GUARD();
+    job = find_block_job_locked(id, &aio_context, errp);
 
     if (!job) {
         return;
@@ -3442,9 +3463,12 @@ void qmp_block_job_finalize(const char *id, Error **errp)
 void qmp_block_job_dismiss(const char *id, Error **errp)
 {
     AioContext *aio_context;
-    BlockJob *bjob = find_block_job(id, &aio_context, errp);
+    BlockJob *bjob;
     Job *job;
 
+    JOB_LOCK_GUARD();
+    bjob = find_block_job_locked(id, &aio_context, errp);
+
     if (!bjob) {
         return;
     }
diff --git a/job-qmp.c b/job-qmp.c
index 270df1eb7e..58ca9b6632 100644
--- a/job-qmp.c
+++ b/job-qmp.c
@@ -29,8 +29,11 @@
 #include "qapi/error.h"
 #include "trace/trace-root.h"
 
-/* Get a job using its ID and acquire its AioContext */
-static Job *find_job(const char *id, AioContext **aio_context, Error **errp)
+/*
+ * Get a block job using its ID and acquire its AioContext.
+ * Called with job_mutex held.
+ */
+static Job *find_job_locked(const char *id, AioContext **aio_context, Error **errp)
 {
     Job *job;
 
@@ -51,7 +54,10 @@ static Job *find_job(const char *id, AioContext **aio_context, Error **errp)
 void qmp_job_cancel(const char *id, Error **errp)
 {
     AioContext *aio_context;
-    Job *job = find_job(id, &aio_context, errp);
+    Job *job;
+
+    JOB_LOCK_GUARD();
+    job = find_job_locked(id, &aio_context, errp);
 
     if (!job) {
         return;
@@ -65,7 +71,10 @@ void qmp_job_cancel(const char *id, Error **errp)
 void qmp_job_pause(const char *id, Error **errp)
 {
     AioContext *aio_context;
-    Job *job = find_job(id, &aio_context, errp);
+    Job *job;
+
+    JOB_LOCK_GUARD();
+    job = find_job_locked(id, &aio_context, errp);
 
     if (!job) {
         return;
@@ -79,7 +88,10 @@ void qmp_job_pause(const char *id, Error **errp)
 void qmp_job_resume(const char *id, Error **errp)
 {
     AioContext *aio_context;
-    Job *job = find_job(id, &aio_context, errp);
+    Job *job;
+
+    JOB_LOCK_GUARD();
+    job = find_job_locked(id, &aio_context, errp);
 
     if (!job) {
         return;
@@ -93,7 +105,10 @@ void qmp_job_resume(const char *id, Error **errp)
 void qmp_job_complete(const char *id, Error **errp)
 {
     AioContext *aio_context;
-    Job *job = find_job(id, &aio_context, errp);
+    Job *job;
+
+    JOB_LOCK_GUARD();
+    job = find_job_locked(id, &aio_context, errp);
 
     if (!job) {
         return;
@@ -107,7 +122,10 @@ void qmp_job_complete(const char *id, Error **errp)
 void qmp_job_finalize(const char *id, Error **errp)
 {
     AioContext *aio_context;
-    Job *job = find_job(id, &aio_context, errp);
+    Job *job;
+
+    JOB_LOCK_GUARD();
+    job = find_job_locked(id, &aio_context, errp);
 
     if (!job) {
         return;
@@ -130,7 +148,10 @@ void qmp_job_finalize(const char *id, Error **errp)
 void qmp_job_dismiss(const char *id, Error **errp)
 {
     AioContext *aio_context;
-    Job *job = find_job(id, &aio_context, errp);
+    Job *job;
+
+    JOB_LOCK_GUARD();
+    job = find_job_locked(id, &aio_context, errp);
 
     if (!job) {
         return;
-- 
2.31.1