2009-02-05 11:16:43

by Vivek Natarajan

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Subject: [PATCH] mac80211: Fix the wrong WARN_ON message appearing on enabling power save.

The warning message intended to be hit on driver's rejection of a Tx frame
is also hit while the netif_subqueue is stopped. This patch fixes this error
case.

Signed-off-by: Vivek Natarajan <[email protected]>
---
net/mac80211/tx.c | 8 +++++---
1 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index f1c726d..bf73f6d 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -35,6 +35,7 @@
#define IEEE80211_TX_OK 0
#define IEEE80211_TX_AGAIN 1
#define IEEE80211_TX_FRAG_AGAIN 2
+#define IEEE80211_TX_PENDING 3

/* misc utils */

@@ -1085,7 +1086,7 @@ static int __ieee80211_tx(struct ieee80211_local *local, struct sk_buff *skb,

if (skb) {
if (netif_subqueue_stopped(local->mdev, skb))
- return IEEE80211_TX_AGAIN;
+ return IEEE80211_TX_PENDING;

ret = local->ops->tx(local_to_hw(local), skb);
if (ret)
@@ -1211,8 +1212,9 @@ retry:
* queues, there's no reason for a driver to reject
* a frame there, warn and drop it.
*/
- if (WARN_ON(info->flags & IEEE80211_TX_CTL_AMPDU))
- goto drop;
+ if (ret != IEEE80211_TX_PENDING)
+ if (WARN_ON(info->flags & IEEE80211_TX_CTL_AMPDU))
+ goto drop;

store = &local->pending_packet[queue];

--
1.6.0.1



2009-02-05 13:36:38

by Johannes Berg

[permalink] [raw]
Subject: Re: [PATCH] mac80211: Fix the wrong WARN_ON message appearing on enabling power save.

On Thu, 2009-02-05 at 17:56 +0530, Vivek Natarajan wrote:
> On Thu, Feb 5, 2009 at 5:37 PM, Johannes Berg <[email protected]> wrote:
> > On Thu, 2009-02-05 at 16:36 +0530, Vivek Natarajan wrote:
> >> The warning message intended to be hit on driver's rejection of a Tx frame
> >> is also hit while the netif_subqueue is stopped. This patch fixes this error
> >> case.
> >
> > This seems a little odd. Why would we be in that code if the queue is
> > stopped?
>
> This issue happens only when we are associated with a 11n AP and power
> save is enabled.
> In the function 'ieee80211_master_start_xmit', ps_disable_work is
> queued where wake_queues is called. But before this work is executed,
> we check if the queues are stopped in _ieee80211_tx and returned
> TX_AGAIN to ieee8011_tx which led to the warning message.

Ah, ok, thanks for the explanation. Might make sense to put that into
the commit message.

johannes


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2009-02-05 12:08:07

by Johannes Berg

[permalink] [raw]
Subject: Re: [PATCH] mac80211: Fix the wrong WARN_ON message appearing on enabling power save.

On Thu, 2009-02-05 at 16:36 +0530, Vivek Natarajan wrote:
> The warning message intended to be hit on driver's rejection of a Tx frame
> is also hit while the netif_subqueue is stopped. This patch fixes this error
> case.

This seems a little odd. Why would we be in that code if the queue is
stopped?

> Signed-off-by: Vivek Natarajan <[email protected]>
> ---
> net/mac80211/tx.c | 8 +++++---
> 1 files changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
> index f1c726d..bf73f6d 100644
> --- a/net/mac80211/tx.c
> +++ b/net/mac80211/tx.c
> @@ -35,6 +35,7 @@
> #define IEEE80211_TX_OK 0
> #define IEEE80211_TX_AGAIN 1
> #define IEEE80211_TX_FRAG_AGAIN 2
> +#define IEEE80211_TX_PENDING 3
>
> /* misc utils */
>
> @@ -1085,7 +1086,7 @@ static int __ieee80211_tx(struct ieee80211_local *local, struct sk_buff *skb,
>
> if (skb) {
> if (netif_subqueue_stopped(local->mdev, skb))
> - return IEEE80211_TX_AGAIN;
> + return IEEE80211_TX_PENDING;
>
> ret = local->ops->tx(local_to_hw(local), skb);
> if (ret)
> @@ -1211,8 +1212,9 @@ retry:
> * queues, there's no reason for a driver to reject
> * a frame there, warn and drop it.
> */
> - if (WARN_ON(info->flags & IEEE80211_TX_CTL_AMPDU))
> - goto drop;
> + if (ret != IEEE80211_TX_PENDING)
> + if (WARN_ON(info->flags & IEEE80211_TX_CTL_AMPDU))
> + goto drop;
>
> store = &local->pending_packet[queue];
>


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2009-02-05 12:26:15

by Vivek Natarajan

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Subject: Re: [PATCH] mac80211: Fix the wrong WARN_ON message appearing on enabling power save.

On Thu, Feb 5, 2009 at 5:37 PM, Johannes Berg <[email protected]> wrote:
> On Thu, 2009-02-05 at 16:36 +0530, Vivek Natarajan wrote:
>> The warning message intended to be hit on driver's rejection of a Tx frame
>> is also hit while the netif_subqueue is stopped. This patch fixes this error
>> case.
>
> This seems a little odd. Why would we be in that code if the queue is
> stopped?

This issue happens only when we are associated with a 11n AP and power
save is enabled.
In the function 'ieee80211_master_start_xmit', ps_disable_work is
queued where wake_queues is called. But before this work is executed,
we check if the queues are stopped in _ieee80211_tx and returned
TX_AGAIN to ieee8011_tx which led to the warning message.

Vivek.