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rt2x00: do not pause queue unconditionally on error path

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[ Upstream commit 6dd80efd75ce7c2dbd9f117cf585ee2b33a42ee1 ]

Pausing queue without checking threshold is racy with txdone path.
Moreover we do not need pause queue on any error, but only if queue
is full - in case when we send RTS frame ( other cases of almost full
queue are already handled in rt2x00queue_write_tx_frame() ).

Patch fixes of theoretically possible problem of pausing empty
queue.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Tested-by: Enrico Mioso <mrkiko.rs@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Stanislaw Gruszka 2017-12-19 12:33:56 +01:00 committed by Greg Kroah-Hartman
parent 1530dcc903
commit f722a6a611
1 changed files with 14 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
drivers/net/wireless/ralink/rt2x00/rt2x00mac.c
View File

@ -142,15 +142,25 @@ void rt2x00mac_tx(struct ieee80211_hw *hw,
if (!rt2x00dev->ops->hw->set_rts_threshold &&
(tx_info->control.rates[0].flags & (IEEE80211_TX_RC_USE_RTS_CTS |
IEEE80211_TX_RC_USE_CTS_PROTECT))) {
if (rt2x00queue_available(queue) <= 1)
goto exit_fail;
if (rt2x00queue_available(queue) <= 1) {
/*
* Recheck for full queue under lock to avoid race
* conditions with rt2x00lib_txdone().
*/
spin_lock(&queue->tx_lock);
if (rt2x00queue_threshold(queue))
rt2x00queue_pause_queue(queue);
spin_unlock(&queue->tx_lock);
goto exit_free_skb;
}
if (rt2x00mac_tx_rts_cts(rt2x00dev, queue, skb))
goto exit_fail;
goto exit_free_skb;
}
if (unlikely(rt2x00queue_write_tx_frame(queue, skb, control->sta, false)))
goto exit_fail;
goto exit_free_skb;
/*
* Pausing queue has to be serialized with rt2x00lib_txdone(). Note
@ -164,10 +174,6 @@ void rt2x00mac_tx(struct ieee80211_hw *hw,
return;
exit_fail:
spin_lock(&queue->tx_lock);
rt2x00queue_pause_queue(queue);
spin_unlock(&queue->tx_lock);
exit_free_skb:
ieee80211_free_txskb(hw, skb);
}