[PATCH 2/2] remoteproc: qcom: Check glink->edge in glink_subdev_stop()

[Jingyi Wang <jingyi.wang@oss.qualcomm.com>]

For rproc that doing attach, glink_subdev_start() is called only when
attach successfully. If rproc_report_crash() is called in the attach
function, rproc_boot_recovery()->rproc_stop()->glink_subdev_stop() could
be called and cause NULL pointer dereference:

 Unable to handle kernel NULL pointer dereference at virtual address 0000000000000300
 Mem abort info:
 ...
 pc : qcom_glink_smem_unregister+0x14/0x48 [qcom_glink_smem]
 lr : glink_subdev_stop+0x1c/0x30 [qcom_common]
 ...
 Call trace:
  qcom_glink_smem_unregister+0x14/0x48 [qcom_glink_smem] (P)
  glink_subdev_stop+0x1c/0x30 [qcom_common]
  rproc_stop+0x58/0x17c
  rproc_trigger_recovery+0xb0/0x150
  rproc_crash_handler_work+0xa4/0xc4
  process_scheduled_works+0x18c/0x2d8
  worker_thread+0x144/0x280
  kthread+0x124/0x138
  ret_from_fork+0x10/0x20
 Code: a9be7bfd 910003fd a90153f3 aa0003f3 (b9430000)
 ---[ end trace 0000000000000000 ]---

Add NULL pointer check in the glink_subdev_stop() to make sure
qcom_glink_smem_unregister() will not be called if glink_subdev_start()
is not called.

Signed-off-by: Jingyi Wang <jingyi.wang@oss.qualcomm.com>
---
 drivers/remoteproc/qcom_common.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/remoteproc/qcom_common.c b/drivers/remoteproc/qcom_common.c
index fd2b6824ad26..79d9d45e0b81 100644
--- a/drivers/remoteproc/qcom_common.c
+++ b/drivers/remoteproc/qcom_common.c
@@ -220,6 +220,9 @@ static void glink_subdev_stop(struct rproc_subdev *subdev, bool crashed)
 {
 	struct qcom_rproc_glink *glink = to_glink_subdev(subdev);
 
+	if (!glink->edge)
+		return;
+
 	qcom_glink_smem_unregister(glink->edge);
 	glink->edge = NULL;
 }

-- 
2.34.1