linux-kernel - [PATCH 5/7] staging: typec: tcpm: Add timeout when waiting for role swap completion

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Message-Id: <1502424945-19969-5-git-send-email-linux@roeck-us.net>
Date:   Thu, 10 Aug 2017 21:15:43 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Badhri Jagan Sridharan <Badhri@...gle.com>,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH 5/7] staging: typec: tcpm: Add timeout when waiting for role swap completion

The Type-C protocol manager state machine could fail, which might result
in role swap requests from user space to hang forever. Add a generous
timeout when waiting for role swaps to complete to avoid this situation.

Originally-from: Badhri Jagan Sridharan <badhri@...gle.com>
Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
 drivers/staging/typec/tcpm.c | 21 +++++++++++++++------
 drivers/staging/typec/tcpm.h |  3 ++-
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/drivers/staging/typec/tcpm.c b/drivers/staging/typec/tcpm.c
index cf498c68c4af..515bec1807d7 100644
--- a/drivers/staging/typec/tcpm.c
+++ b/drivers/staging/typec/tcpm.c
@@ -3166,9 +3166,12 @@ static int tcpm_dr_set(const struct typec_capability *cap,
 	tcpm_set_state(port, DR_SWAP_SEND, 0);
 	mutex_unlock(&port->lock);
 
-	wait_for_completion(&port->swap_complete);
+	if (!wait_for_completion_timeout(&port->swap_complete,
+				msecs_to_jiffies(PD_ROLE_SWAP_TIMEOUT)))
+		ret = -ETIMEDOUT;
+	else
+		ret = port->swap_status;
 
-	ret = port->swap_status;
 	goto swap_unlock;
 
 port_unlock:
@@ -3223,9 +3226,12 @@ static int tcpm_pr_set(const struct typec_capability *cap,
 	tcpm_set_state(port, PR_SWAP_SEND, 0);
 	mutex_unlock(&port->lock);
 
-	wait_for_completion(&port->swap_complete);
+	if (!wait_for_completion_timeout(&port->swap_complete,
+				msecs_to_jiffies(PD_ROLE_SWAP_TIMEOUT)))
+		ret = -ETIMEDOUT;
+	else
+		ret = port->swap_status;
 
-	ret = port->swap_status;
 	goto swap_unlock;
 
 port_unlock:
@@ -3260,9 +3266,12 @@ static int tcpm_vconn_set(const struct typec_capability *cap,
 	tcpm_set_state(port, VCONN_SWAP_SEND, 0);
 	mutex_unlock(&port->lock);
 
-	wait_for_completion(&port->swap_complete);
+	if (!wait_for_completion_timeout(&port->swap_complete,
+				msecs_to_jiffies(PD_ROLE_SWAP_TIMEOUT)))
+		ret = -ETIMEDOUT;
+	else
+		ret = port->swap_status;
 
-	ret = port->swap_status;
 	goto swap_unlock;
 
 port_unlock:
diff --git a/drivers/staging/typec/tcpm.h b/drivers/staging/typec/tcpm.h
index 4c6b38cb2c8a..374cea44a84a 100644
--- a/drivers/staging/typec/tcpm.h
+++ b/drivers/staging/typec/tcpm.h
@@ -34,7 +34,8 @@ enum typec_cc_polarity {
 };
 
 /* Time to wait for TCPC to complete transmit */
-#define PD_T_TCPC_TX_TIMEOUT  100
+#define PD_T_TCPC_TX_TIMEOUT	100		/* in ms	*/
+#define PD_ROLE_SWAP_TIMEOUT	(MSEC_PER_SEC * 10)
 
 enum tcpm_transmit_status {
 	TCPC_TX_SUCCESS = 0,
-- 
2.7.4