[PATCH V2] remoteproc: imx_rproc: Add mutex protection for workqueue

["Peng Fan (OSS)" <peng.fan@oss.nxp.com>]

From: Peng Fan <peng.fan@nxp.com>

Same as commit 47e6ab07018e ("remoteproc: imx_dsp_rproc: Add mutex
protection for workqueue") and commit 35bdafda40cc ("remoteproc:
stm32_rproc: Add mutex protection for workqueue"), imx_rproc driver
also has similar issue, although no issue reported until now.

The workqueue may execute late even after remoteproc is stopped or
stopping, some resources (rpmsg device and endpoint) have been
released in rproc_stop_subdevices(), then rproc_vq_interrupt()
accessing these resources will cause kennel dump.

Call trace:
 virtqueue_add_split
 virtqueue_add_inbuf
 rpmsg_recv_done
 vring_interrupt
 rproc_vq_interrupt
 imx_rproc_vq_work
 process_one_work
 worker_thread
 kthread
 ret_from_fork

Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
---

V2:
 Add RPROC_ATTACHED check, because i.MX supports remote cores started by
 bootloader.
 Update commit and add R-b from Frank

 drivers/remoteproc/imx_rproc.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/remoteproc/imx_rproc.c b/drivers/remoteproc/imx_rproc.c
index 74299af1d7f1..4819a9e57543 100644
--- a/drivers/remoteproc/imx_rproc.c
+++ b/drivers/remoteproc/imx_rproc.c
@@ -5,6 +5,7 @@
 
 #include <dt-bindings/firmware/imx/rsrc.h>
 #include <linux/arm-smccc.h>
+#include <linux/cleanup.h>
 #include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/firmware/imx/sci.h>
@@ -785,6 +786,11 @@ static void imx_rproc_vq_work(struct work_struct *work)
 					      rproc_work);
 	struct rproc *rproc = priv->rproc;
 
+	guard(mutex)(&rproc->lock);
+
+	if (rproc->state != RPROC_RUNNING && rproc->state != RPROC_ATTACHED)
+		return;
+
 	idr_for_each(&rproc->notifyids, imx_rproc_notified_idr_cb, rproc);
 }
 
-- 
2.37.1