[PATCH v16 02/16] accel/rocket: take the completion register writes under job_lock

[Jiaxing Hu]

The IRQ handler writes OPERATION_ENABLE and INTERRUPT_CLEAR before it
takes job_lock, while rocket_job_hw_submit() sets OPERATION_ENABLE to 1
under that lock.

If the two run at the same time, the 0 written by the IRQ handler can
overwrite the 1 written for a new task and stop a task that has just
started.

Move both writes into the existing scoped_guard(), so they are under the
same lock as the submit.

Fixes: 0810d5ad88a1 ("accel/rocket: Add job submission IOCTL")
Signed-off-by: Jiaxing Hu <gahing at gahingwoo.com>
Tested-by: Igor Paunovic <royalnet026 at gmail.com> # RK3588, three cores, induced reset, JOB_TIMEOUT_MS=2
Reviewed-by: Heiko Stuebner <heiko at sntech.de>
---
 drivers/accel/rocket/rocket_job.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/accel/rocket/rocket_job.c b/drivers/accel/rocket/rocket_job.c
index c3edb94355a3..03e5f094f60b 100644
--- a/drivers/accel/rocket/rocket_job.c
+++ b/drivers/accel/rocket/rocket_job.c
@@ -369,10 +369,15 @@ static void rocket_job_handle_irq(struct rocket_core *core)
 {
 	pm_runtime_mark_last_busy(core->dev);
 
-	rocket_pc_writel(core, OPERATION_ENABLE, 0x0);
-	rocket_pc_writel(core, INTERRUPT_CLEAR, 0x1ffff);
+	scoped_guard(mutex, &core->job_lock) {
+		/*
+		 * Stopping the block belongs under the lock. hw_submit() writes
+		 * OPERATION_ENABLE too, and outside the lock this zero can land
+		 * after that one and stop a task that has only just started.
+		 */
+		rocket_pc_writel(core, OPERATION_ENABLE, 0x0);
+		rocket_pc_writel(core, INTERRUPT_CLEAR, 0x1ffff);
 
-	scoped_guard(mutex, &core->job_lock)
 		if (core->in_flight_job) {
 			if (core->in_flight_job->next_task_idx < core->in_flight_job->task_count) {
 				rocket_job_hw_submit(core, core->in_flight_job);
@@ -384,6 +389,7 @@ static void rocket_job_handle_irq(struct rocket_core *core)
 			pm_runtime_put_autosuspend(core->dev);
 			core->in_flight_job = NULL;
 		}
+	}
 }
 
 static void
-- 
2.43.0