From: "John W. Linville" <linville@tuxdriver.com>
To: Felix Fietkau <nbd@openwrt.org>
Cc: linux-wireless@vger.kernel.org, mcgrof@qca.qualcomm.com
Subject: Re: [PATCH 5/6] ath9k: simplify tx locking
Date: Tue, 13 Dec 2011 15:47:17 -0500 [thread overview]
Message-ID: <20111213204717.GD2613@tuxdriver.com> (raw)
In-Reply-To: <1323720386-46132-5-git-send-email-nbd@openwrt.org>
On Mon, Dec 12, 2011 at 09:06:25PM +0100, Felix Fietkau wrote:
> Instead of releasing and taking back the lock over and over again in the
> tx path, hold the lock a bit longer, requiring much fewer lock/unlock pairs.
> This makes locking much easier to review and should not have any noticeable
> performance/latency impact.
>
> Signed-off-by: Felix Fietkau <nbd@openwrt.org>
> @@ -2259,6 +2230,7 @@ void ath_tx_edma_tasklet(struct ath_softc *sc)
> struct list_head bf_head;
> int status;
>
> + spin_lock_bh(&txq->axq_lock);
> for (;;) {
> if (work_pending(&sc->hw_reset_work))
> break;
Pretty sure this is wrong -- gcc seems to agree:
CC [M] drivers/net/wireless/ath/ath9k/xmit.o
drivers/net/wireless/ath/ath9k/xmit.c: In function ‘ath_tx_edma_tasklet’:
drivers/net/wireless/ath/ath9k/xmit.c:2249:18: warning: ‘txq’ may be used uninitialized in this function
> @@ -2278,12 +2250,8 @@ void ath_tx_edma_tasklet(struct ath_softc *sc)
>
> txq = &sc->tx.txq[ts.qid];
>
> - spin_lock_bh(&txq->axq_lock);
> -
> - if (list_empty(&txq->txq_fifo[txq->txq_tailidx])) {
> - spin_unlock_bh(&txq->axq_lock);
> - return;
> - }
> + if (list_empty(&txq->txq_fifo[txq->txq_tailidx]))
> + break;
>
> bf = list_first_entry(&txq->txq_fifo[txq->txq_tailidx],
> struct ath_buf, list);
Looks like txq doesn't get initialized until this loop?
--
John W. Linville Someday the world will need a hero, and you
linville@tuxdriver.com might be all we have. Be ready.
prev parent reply other threads:[~2011-12-13 21:00 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-12 20:06 [PATCH 1/6] ath9k: change maximum software retransmission handling Felix Fietkau
2011-12-12 20:06 ` [PATCH 2/6] ath9k: reduce the number of unnecessary BAR tx packets Felix Fietkau
2011-12-12 20:06 ` [PATCH 3/6] ath9k: reduce indentation level in a few places Felix Fietkau
2011-12-12 20:06 ` [PATCH 4/6] ath9k: remove bogus sequence number increment Felix Fietkau
2011-12-12 20:06 ` [PATCH 5/6] ath9k: simplify tx locking Felix Fietkau
2011-12-12 20:06 ` [PATCH 6/6] ath9k: avoid retransmitting aggregation frames that a BAR was sent for Felix Fietkau
2011-12-13 20:47 ` John W. Linville [this message]
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