From c05dfce0b89e3b58043805b6f4bdf30e3561d867 Mon Sep 17 00:00:00 2001 From: Bjorn Andersson Date: Mon, 27 Mar 2023 07:46:17 -0700 Subject: [PATCH] rpmsg: glink: Wait for intent, not just request ack In some implementations of the remote firmware, an intent request acknowledgment is sent when it's determined if the intent allocation will be fulfilled, but then the intent is queued after the acknowledgment. The result is that upon receiving a granted allocation request, the search for the newly allocated intent will fail and an additional request will be made. This will at best waste memory, but if the second request is rejected the transaction will be incorrectly rejected. Take the incoming intent into account in the wait to mitigate this problem. The above scenario can still happen, in the case that, on that same channel, an unrelated intent is delivered prior to the request acknowledgment and a separate process enters the send path and picks up the intent. Given that there's no relationship between the acknowledgment and the delivered (or to be delivered intent), there doesn't seem to be a solution to this problem. Signed-off-by: Bjorn Andersson Reviewed-by: Chris Lew [bjorn: Fixed spelling issues pointed out by checkpatch in commit message] Signed-off-by: Bjorn Andersson Link: https://lore.kernel.org/r/20230327144617.3134175-3-quic_bjorande@quicinc.com --- drivers/rpmsg/qcom_glink_native.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c index 0b6291f..196ca7d8 100644 --- a/drivers/rpmsg/qcom_glink_native.c +++ b/drivers/rpmsg/qcom_glink_native.c @@ -146,6 +146,7 @@ enum { * @open_req: completed once open-request has been received * @intent_req_lock: Synchronises multiple intent requests * @intent_req_result: Result of intent request + * @intent_received: flag indicating that an intent has been received * @intent_req_wq: wait queue for intent_req signalling */ struct glink_channel { @@ -177,6 +178,7 @@ struct glink_channel { struct mutex intent_req_lock; int intent_req_result; + bool intent_received; wait_queue_head_t intent_req_wq; }; @@ -420,13 +422,13 @@ static void qcom_glink_handle_intent_req_ack(struct qcom_glink *glink, return; } - channel->intent_req_result = granted; + WRITE_ONCE(channel->intent_req_result, granted); wake_up_all(&channel->intent_req_wq); } static void qcom_glink_intent_req_abort(struct glink_channel *channel) { - channel->intent_req_result = 0; + WRITE_ONCE(channel->intent_req_result, 0); wake_up_all(&channel->intent_req_wq); } @@ -757,6 +759,11 @@ static void qcom_glink_handle_rx_done(struct qcom_glink *glink, kfree(intent); } spin_unlock_irqrestore(&channel->intent_lock, flags); + + if (reuse) { + WRITE_ONCE(channel->intent_received, true); + wake_up_all(&channel->intent_req_wq); + } } /** @@ -994,6 +1001,9 @@ static void qcom_glink_handle_intent(struct qcom_glink *glink, dev_err(glink->dev, "failed to store remote intent\n"); } + WRITE_ONCE(channel->intent_received, true); + wake_up_all(&channel->intent_req_wq); + kfree(msg); qcom_glink_rx_advance(glink, ALIGN(msglen, 8)); } @@ -1273,6 +1283,7 @@ static int qcom_glink_request_intent(struct qcom_glink *glink, mutex_lock(&channel->intent_req_lock); WRITE_ONCE(channel->intent_req_result, -1); + WRITE_ONCE(channel->intent_received, false); cmd.id = GLINK_CMD_RX_INTENT_REQ; cmd.cid = channel->lcid; @@ -1283,7 +1294,8 @@ static int qcom_glink_request_intent(struct qcom_glink *glink, goto unlock; ret = wait_event_timeout(channel->intent_req_wq, - READ_ONCE(channel->intent_req_result) >= 0, + READ_ONCE(channel->intent_req_result) >= 0 && + READ_ONCE(channel->intent_received), 10 * HZ); if (!ret) { dev_err(glink->dev, "intent request timed out\n"); -- 2.7.4