Date:   Mon, 25 Mar 2019 15:31:52 +0100
From:   Stanislaw Gruszka <sgruszka@redhat.com>
To:     Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Cc:     Lorenzo Bianconi <lorenzo@kernel.org>, nbd@nbd.name,
        linux-wireless@vger.kernel.org
Subject: Re: [PATCH] mt76: usb: reduce locking in mt76u_tx_tasklet
Message-ID: <20190325143152.GB13884@redhat.com>
References: <cover.1553437543.git.lorenzo@kernel.org>
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 <20190325125032.GB17956@redhat.com>
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 <20190325131019.GA19204@redhat.com>
 <20190325134734.GB12885@localhost.localdomain>
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On Mon, Mar 25, 2019 at 02:47:35PM +0100, Lorenzo Bianconi wrote:
> > On Mon, Mar 25, 2019 at 02:00:36PM +0100, Lorenzo Bianconi wrote:
> > > > On Sun, Mar 24, 2019 at 03:51:43PM +0100, Lorenzo Bianconi wrote:
> > > > > +		int idx;
> > > > > +
> > > > >  		sq = &dev->q_tx[i];
> > > > >  		q = sq->q;
> > > > >  
> > > > > -		spin_lock_bh(&q->lock);
> > > > > -		while (true) {
> > > > > -			if (!q->entry[q->head].done || !q->queued)
> > > > > +		while (q->queued > n_queued) {
> > > > > +			if (!q->entry[q->head].done)
> > > > >  				break;
> > > > If you place done = false here you will not need additional idx
> > > > variable.
> > > 
> > > As Felix suggested, I would set done to false at the end of the loop, after
> > > tx_complete_skb
> > Why this is needed? 
> 
> logically I think it should be the last thing to do on the current skb but
Why? This is only marker that urb complete was done.

> probably moving it before tx_complete_skb will not make any difference
It will not, since code is performed in the same tasklet.

Stanislaw