linux-kernel - [PATCH 4.8 43/67] iwlwifi: mvm: wake the wait queue when the RX sync counter is zero

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Date:   Thu, 24 Nov 2016 16:27:37 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Sara Sharon <sara.sharon@...el.com>,
        Luca Coelho <luciano.coelho@...el.com>
Subject: [PATCH 4.8 43/67] iwlwifi: mvm: wake the wait queue when the RX sync counter is zero

4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sara Sharon <sara.sharon@...el.com>

commit 3a732c65de427fdae67a243fd331356034b5a1e8 upstream.

When we sync the RX queues the driver waits to receive echo
notification on all the RX queues.
The wait queue is set with timeout until all queues have received
the notification.
However, iwl_mvm_rx_queue_notif() never woke up the wait queue,
with the result of the counter value being checked only when the
timeout expired.
This may cause a latency of up to 1 second.

Fixes: 0636b938214c ("iwlwifi: mvm: implement driver RX queues sync command")
Signed-off-by: Sara Sharon <sara.sharon@...el.com>
Signed-off-by: Luca Coelho <luciano.coelho@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c |    3 +--
 drivers/net/wireless/intel/iwlwifi/mvm/mvm.h      |    1 +
 drivers/net/wireless/intel/iwlwifi/mvm/ops.c      |    1 +
 drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c     |    3 ++-
 4 files changed, 5 insertions(+), 3 deletions(-)

--- a/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c
@@ -4097,7 +4097,6 @@ void iwl_mvm_sync_rx_queues_internal(str
 				     struct iwl_mvm_internal_rxq_notif *notif,
 				     u32 size)
 {
-	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(notif_waitq);
 	u32 qmask = BIT(mvm->trans->num_rx_queues) - 1;
 	int ret;
 
@@ -4119,7 +4118,7 @@ void iwl_mvm_sync_rx_queues_internal(str
 	}
 
 	if (notif->sync)
-		ret = wait_event_timeout(notif_waitq,
+		ret = wait_event_timeout(mvm->rx_sync_waitq,
 					 atomic_read(&mvm->queue_sync_counter) == 0,
 					 HZ);
 	WARN_ON_ONCE(!ret);
--- a/drivers/net/wireless/intel/iwlwifi/mvm/mvm.h
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/mvm.h
@@ -932,6 +932,7 @@ struct iwl_mvm {
 	/* sync d0i3_tx queue and IWL_MVM_STATUS_IN_D0I3 status flag */
 	spinlock_t d0i3_tx_lock;
 	wait_queue_head_t d0i3_exit_waitq;
+	wait_queue_head_t rx_sync_waitq;
 
 	/* BT-Coex */
 	struct iwl_bt_coex_profile_notif last_bt_notif;
--- a/drivers/net/wireless/intel/iwlwifi/mvm/ops.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/ops.c
@@ -618,6 +618,7 @@ iwl_op_mode_mvm_start(struct iwl_trans *
 	spin_lock_init(&mvm->refs_lock);
 	skb_queue_head_init(&mvm->d0i3_tx);
 	init_waitqueue_head(&mvm->d0i3_exit_waitq);
+	init_waitqueue_head(&mvm->rx_sync_waitq);
 
 	atomic_set(&mvm->queue_sync_counter, 0);
 
--- a/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c
@@ -545,7 +545,8 @@ void iwl_mvm_rx_queue_notif(struct iwl_m
 				  "Received expired RX queue sync message\n");
 			return;
 		}
-		atomic_dec(&mvm->queue_sync_counter);
+		if (!atomic_dec_return(&mvm->queue_sync_counter))
+			wake_up(&mvm->rx_sync_waitq);
 	}
 
 	switch (internal_notif->type) {