| Message ID | 1513683236-13402-2-git-send-email-sgruszka@redhat.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 6dd80efd75ce7c2dbd9f117cf585ee2b33a42ee1 |
| Delegated to: | Kalle Valo |
| Headers | show |
On a WL-330N3G device, these patches seems to make the situation much better. In other words, I wasn't able to reproduce the stall on this chipset. On MT7620 a stall was never seen directly, but tests with these patches revealed no stall. So I think it's good to have these merged. Tested-by: Enrico Mioso <mrkiko.rs@gmail.com> On Tue, 19 Dec 2017, Stanislaw Gruszka wrote: > Date: Tue, 19 Dec 2017 12:33:56 > From: Stanislaw Gruszka <sgruszka@redhat.com> > To: linux-wireless@vger.kernel.org > Cc: Helmut Schaa <helmut.schaa@googlemail.com>, > Enrico Mioso <mrkiko.rs@gmail.com>, Daniel Golle <daniel@makrotopia.org>, > Felix Fietkau <nbd@nbd.name>, Stanislaw Gruszka <sgruszka@redhat.com> > Subject: [PATCH 2/2] rt2x00: do not pause queue unconditionally on error path > > 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> > --- > drivers/net/wireless/ralink/rt2x00/rt2x00mac.c | 22 ++++++++++++++-------- > 1 file changed, 14 insertions(+), 8 deletions(-) > > diff --git a/drivers/net/wireless/ralink/rt2x00/rt2x00mac.c b/drivers/net/wireless/ralink/rt2x00/rt2x00mac.c > index c8a6f163102f..a971bc7a6b63 100644 > --- a/drivers/net/wireless/ralink/rt2x00/rt2x00mac.c > +++ b/drivers/net/wireless/ralink/rt2x00/rt2x00mac.c > @@ -142,22 +142,28 @@ 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; > > 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); > } > -- > 1.9.3 > >
diff --git a/drivers/net/wireless/ralink/rt2x00/rt2x00mac.c b/drivers/net/wireless/ralink/rt2x00/rt2x00mac.c index c8a6f163102f..a971bc7a6b63 100644 --- a/drivers/net/wireless/ralink/rt2x00/rt2x00mac.c +++ b/drivers/net/wireless/ralink/rt2x00/rt2x00mac.c @@ -142,22 +142,28 @@ 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; 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); }
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> --- drivers/net/wireless/ralink/rt2x00/rt2x00mac.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-)