[5/5] rpmsg: smd: Don't hold the tx lock during wait

Message ID 20171212235857.10432-6-bjorn.andersson@linaro.org
State Accepted
Commit 178f3f75bb4ef7a29bf5c175eb33794ac9ae9bce
Headers show
Series
  • Qualcomm SMD updates
Related show

Commit Message

Bjorn Andersson Dec. 12, 2017, 11:58 p.m.
Holding the tx lock while waiting for tx-drain events from the remote
side blocks try_send requests from failing quickly, so temporarily drop
the tx lock while waiting.

While this allows try_send to fail quickly it also could allow a
subsequent send to succeed putting a smaller packet in the FIFO while
we're waiting for room for our large packet. But as this lock is per
channel we expect that clients with ordering concerns implements their
own ordering mechanism.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

---
 drivers/rpmsg/qcom_smd.c | 7 +++++++
 1 file changed, 7 insertions(+)

-- 
2.15.0

Patch

diff --git a/drivers/rpmsg/qcom_smd.c b/drivers/rpmsg/qcom_smd.c
index ed167ab52a68..10870189c0c8 100644
--- a/drivers/rpmsg/qcom_smd.c
+++ b/drivers/rpmsg/qcom_smd.c
@@ -752,12 +752,19 @@  static int __qcom_smd_send(struct qcom_smd_channel *channel, const void *data,
 
 		SET_TX_CHANNEL_FLAG(channel, fBLOCKREADINTR, 0);
 
+		/* Wait without holding the tx_lock */
+		mutex_unlock(&channel->tx_lock);
+
 		ret = wait_event_interruptible(channel->fblockread_event,
 				       qcom_smd_get_tx_avail(channel) >= tlen ||
 				       channel->state != SMD_CHANNEL_OPENED);
 		if (ret)
 			goto out;
 
+		ret = mutex_lock_interruptible(&channel->tx_lock);
+		if (ret)
+			goto out;
+
 		SET_TX_CHANNEL_FLAG(channel, fBLOCKREADINTR, 1);
 	}