[PATCH] slimbus: messaging: Free transaction ID in delayed interrupt scenario

[Visweswara Tanuku <quic_vtanuku@xxxxxxxxxxx>]

In case of interrupt delay for any reason, slim_do_transfer()
returns timeout error but the transaction ID (TID) is not freed.
This results into invalid memory access inside
qcom_slim_ngd_rx_msgq_cb() due to invalid TID.

Fix the issue by freeing the TID in slim_do_transfer() before
returning timeout error to avoid invalid memory access.

Call trace:
__memcpy_fromio+0x20/0x190
qcom_slim_ngd_rx_msgq_cb+0x130/0x290 [slim_qcom_ngd_ctrl]
vchan_complete+0x2a0/0x4a0
tasklet_action_common+0x274/0x700
tasklet_action+0x28/0x3c
_stext+0x188/0x620
run_ksoftirqd+0x34/0x74
smpboot_thread_fn+0x1d8/0x464
kthread+0x178/0x238
ret_from_fork+0x10/0x20
Code: aa0003e8 91000429 f100044a 3940002b (3800150b)
---[ end trace 0fe00bec2b975c99 ]---
Kernel panic - not syncing: Oops: Fatal exception in interrupt.

Signed-off-by: Visweswara Tanuku <quic_vtanuku@xxxxxxxxxxx>
---
 drivers/slimbus/messaging.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/slimbus/messaging.c b/drivers/slimbus/messaging.c
index 242570a5e565..455c1fd1490f 100644
--- a/drivers/slimbus/messaging.c
+++ b/drivers/slimbus/messaging.c
@@ -148,8 +148,9 @@ int slim_do_transfer(struct slim_controller *ctrl, struct slim_msg_txn *txn)
 	}
 
 	ret = ctrl->xfer_msg(ctrl, txn);
-
-	if (!ret && need_tid && !txn->msg->comp) {
+	if (ret == -ETIMEDOUT) {
+		slim_free_txn_tid(ctrl, txn);
+	} else if (!ret && need_tid && !txn->msg->comp) {
 		unsigned long ms = txn->rl + HZ;
 
 		time_left = wait_for_completion_timeout(txn->comp,
-- 
2.17.1