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From: Bob Copeland <me@bobcopeland.com>
To: Niklas Cassel <niklas.cassel@linaro.org>
Cc: Adrian Chadd <adrian.chadd@gmail.com>,
	netdev@vger.kernel.org, linux-wireless@vger.kernel.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	ath10k@lists.infradead.org, Kalle Valo <kvalo@qca.qualcomm.com>,
	David Miller <davem@davemloft.net>
Subject: Re: [PATCH] ath10k: transmit queued frames after waking queues
Date: Thu, 24 May 2018 11:50:34 -0400	[thread overview]
Message-ID: <20180524155034.xse7cfm5figfktuj@localhost> (raw)
In-Reply-To: <20180521203701.GA7619@localhost.localdomain>

On Mon, May 21, 2018 at 10:37:01PM +0200, Niklas Cassel wrote:
> On Thu, May 17, 2018 at 03:26:25PM -0700, Adrian Chadd wrote:
> > On Thu, 17 May 2018 at 16:16, Niklas Cassel <niklas.cassel@linaro.org>
> > wrote:
> > 
> > > diff --git a/drivers/net/wireless/ath/ath10k/txrx.c
> > b/drivers/net/wireless/ath/ath10k/txrx.c
> > > index cda164f6e9f6..1d3b2d2c3fee 100644
> > > --- a/drivers/net/wireless/ath/ath10k/txrx.c
> > > +++ b/drivers/net/wireless/ath/ath10k/txrx.c
> > > @@ -95,6 +95,9 @@ int ath10k_txrx_tx_unref(struct ath10k_htt *htt,
> > >                  wake_up(&htt->empty_tx_wq);
> > >          spin_unlock_bh(&htt->tx_lock);
> > 
> > > +       if (htt->num_pending_tx <= 3 && !list_empty(&ar->txqs))
> > > +               ath10k_mac_tx_push_pending(ar);
> > > +
> > 
> > Just sanity checking - what's protecting htt->num_pending_tx? or is it
> > serialised some other way?
[...]
> I can't see that any of the examples applies, but let's add READ_ONCE(),
> to make sure that the compiler doesn't try to optimize this.

Couldn't you just move the num_pending_tx read inside tx_lock which is 2 lines
above?  I think all the other manipulations are protected by tx_lock.

-- 
Bob Copeland %% https://bobcopeland.com/

_______________________________________________
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ath10k@lists.infradead.org
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WARNING: multiple messages have this Message-ID (diff)
From: Bob Copeland <me@bobcopeland.com>
To: Niklas Cassel <niklas.cassel@linaro.org>
Cc: Adrian Chadd <adrian.chadd@gmail.com>,
	Kalle Valo <kvalo@qca.qualcomm.com>,
	David Miller <davem@davemloft.net>,
	ath10k@lists.infradead.org, linux-wireless@vger.kernel.org,
	netdev@vger.kernel.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] ath10k: transmit queued frames after waking queues
Date: Thu, 24 May 2018 11:50:34 -0400	[thread overview]
Message-ID: <20180524155034.xse7cfm5figfktuj@localhost> (raw)
In-Reply-To: <20180521203701.GA7619@localhost.localdomain>

On Mon, May 21, 2018 at 10:37:01PM +0200, Niklas Cassel wrote:
> On Thu, May 17, 2018 at 03:26:25PM -0700, Adrian Chadd wrote:
> > On Thu, 17 May 2018 at 16:16, Niklas Cassel <niklas.cassel@linaro.org>
> > wrote:
> > 
> > > diff --git a/drivers/net/wireless/ath/ath10k/txrx.c
> > b/drivers/net/wireless/ath/ath10k/txrx.c
> > > index cda164f6e9f6..1d3b2d2c3fee 100644
> > > --- a/drivers/net/wireless/ath/ath10k/txrx.c
> > > +++ b/drivers/net/wireless/ath/ath10k/txrx.c
> > > @@ -95,6 +95,9 @@ int ath10k_txrx_tx_unref(struct ath10k_htt *htt,
> > >                  wake_up(&htt->empty_tx_wq);
> > >          spin_unlock_bh(&htt->tx_lock);
> > 
> > > +       if (htt->num_pending_tx <= 3 && !list_empty(&ar->txqs))
> > > +               ath10k_mac_tx_push_pending(ar);
> > > +
> > 
> > Just sanity checking - what's protecting htt->num_pending_tx? or is it
> > serialised some other way?
[...]
> I can't see that any of the examples applies, but let's add READ_ONCE(),
> to make sure that the compiler doesn't try to optimize this.

Couldn't you just move the num_pending_tx read inside tx_lock which is 2 lines
above?  I think all the other manipulations are protected by tx_lock.

-- 
Bob Copeland %% https://bobcopeland.com/

  reply	other threads:[~2018-05-24 15:50 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-17 23:15 [PATCH] ath10k: transmit queued frames after waking queues Niklas Cassel
2018-05-17 23:15 ` Niklas Cassel
2018-05-17 22:26 ` Adrian Chadd
2018-05-17 22:26   ` Adrian Chadd
2018-05-21 20:37   ` Niklas Cassel
2018-05-21 20:37     ` Niklas Cassel
2018-05-24 15:50     ` Bob Copeland [this message]
2018-05-24 15:50       ` Bob Copeland
2018-05-25 12:36       ` Niklas Cassel
2018-05-25 12:36         ` Niklas Cassel
2018-05-25 12:50         ` Bob Copeland
2018-05-25 12:50           ` Bob Copeland
2018-05-25 14:21           ` Niklas Cassel
2018-05-25 14:21             ` Niklas Cassel

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