[PATCH v7 05/18] job.h: add _locked duplicates for job API functions called with and without job_mutex

[Emanuele Giuseppe Esposito]

In preparation to the job_lock/unlock usage, create _locked
duplicates of some functions, since they will be sometimes called with
job_mutex held (mostly within job.c),
and sometimes without (mostly from JobDrivers using the job API).

Therefore create a _locked version of such function, so that it
can be used in both cases.

List of functions duplicated as _locked:
job_is_ready (both versions are public)
job_is_completed (both versions are public)
job_is_cancelled (_locked version is public, needed by mirror.c)
job_pause_point (_locked version is static, purely done to simplify the code)
job_cancel_requested (_locked version is static)

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

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
---
 include/qemu/job.h | 25 +++++++++++++++++++++---
 job.c              | 48 ++++++++++++++++++++++++++++++++++++++++------
 2 files changed, 64 insertions(+), 9 deletions(-)

diff --git a/include/qemu/job.h b/include/qemu/job.h
index 4b64eb15f7..275d593715 100644
--- a/include/qemu/job.h
+++ b/include/qemu/job.h
@@ -475,21 +475,40 @@ const char *job_type_str(const Job *job);
 /** Returns true if the job should not be visible to the management layer. */
 bool job_is_internal(Job *job);
 
-/** Returns whether the job is being cancelled. */
+/**
+ * Returns whether the job is being cancelled.
+ * Called with job_mutex *not* held.
+ */
 bool job_is_cancelled(Job *job);
 
+/** Just like job_is_cancelled, but called between job_lock and job_unlock */
+bool job_is_cancelled_locked(Job *job);
+
 /**
  * Returns whether the job is scheduled for cancellation (at an
  * indefinite point).
+ * Called with job_mutex *not* held.
  */
 bool job_cancel_requested(Job *job);
 
-/** Returns whether the job is in a completed state. */
+/**
+ * Returns whether the job is in a completed state.
+ * Called with job_mutex *not* held.
+ */
 bool job_is_completed(Job *job);
 
-/** Returns whether the job is ready to be completed. */
+/** Just like job_is_completed, but called between job_lock and job_unlock */
+bool job_is_completed_locked(Job *job);
+
+/**
+ * Returns whether the job is ready to be completed.
+ * Called with job_mutex *not* held.
+ */
 bool job_is_ready(Job *job);
 
+/** Just like job_is_ready, but called between job_lock and job_unlock */
+bool job_is_ready_locked(Job *job);
+
 /**
  * Request @job to pause at the next pause point. Must be paired with
  * job_resume(). If the job is supposed to be resumed by user action, call
diff --git a/job.c b/job.c
index cafd597ba4..c4776985c4 100644
--- a/job.c
+++ b/job.c
@@ -236,19 +236,32 @@ const char *job_type_str(const Job *job)
     return JobType_str(job_type(job));
 }
 
-bool job_is_cancelled(Job *job)
+bool job_is_cancelled_locked(Job *job)
 {
     /* force_cancel may be true only if cancelled is true, too */
     assert(job->cancelled || !job->force_cancel);
     return job->force_cancel;
 }
 
-bool job_cancel_requested(Job *job)
+bool job_is_cancelled(Job *job)
+{
+    JOB_LOCK_GUARD();
+    return job_is_cancelled_locked(job);
+}
+
+/* Called with job_mutex held. */
+static bool job_cancel_requested_locked(Job *job)
 {
     return job->cancelled;
 }
 
-bool job_is_ready(Job *job)
+bool job_cancel_requested(Job *job)
+{
+    JOB_LOCK_GUARD();
+    return job_cancel_requested_locked(job);
+}
+
+bool job_is_ready_locked(Job *job)
 {
     switch (job->status) {
     case JOB_STATUS_UNDEFINED:
@@ -270,7 +283,13 @@ bool job_is_ready(Job *job)
     return false;
 }
 
-bool job_is_completed(Job *job)
+bool job_is_ready(Job *job)
+{
+    JOB_LOCK_GUARD();
+    return job_is_ready_locked(job);
+}
+
+bool job_is_completed_locked(Job *job)
 {
     switch (job->status) {
     case JOB_STATUS_UNDEFINED:
@@ -292,6 +311,12 @@ bool job_is_completed(Job *job)
     return false;
 }
 
+bool job_is_completed(Job *job)
+{
+    JOB_LOCK_GUARD();
+    return job_is_completed_locked(job);
+}
+
 static bool job_started(Job *job)
 {
     return job->co;
@@ -521,7 +546,8 @@ static void coroutine_fn job_do_yield(Job *job, uint64_t ns)
     assert(job->busy);
 }
 
-void coroutine_fn job_pause_point(Job *job)
+/* Called with job_mutex held, but releases it temporarily. */
+static void coroutine_fn job_pause_point_locked(Job *job)
 {
     assert(job && job_started(job));
 
@@ -552,6 +578,12 @@ void coroutine_fn job_pause_point(Job *job)
     }
 }
 
+void coroutine_fn job_pause_point(Job *job)
+{
+    JOB_LOCK_GUARD();
+    job_pause_point_locked(job);
+}
+
 void job_yield(Job *job)
 {
     assert(job->busy);
@@ -949,11 +981,15 @@ static void job_completed(Job *job)
     }
 }
 
-/** Useful only as a type shim for aio_bh_schedule_oneshot. */
+/**
+ * Useful only as a type shim for aio_bh_schedule_oneshot.
+ * Called with job_mutex *not* held.
+ */
 static void job_exit(void *opaque)
 {
     Job *job = (Job *)opaque;
     AioContext *ctx;
+    JOB_LOCK_GUARD();
 
     job_ref(job);
     aio_context_acquire(job->aio_context);
-- 
2.31.1