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Message-ID: <91161723-6968-17f1-e1af-b9c85b2ab55f@engleder-embedded.com> Date: Tue, 10 Jan 2023 20:44:33 +0100 From: Gerhard Engleder <gerhard@...leder-embedded.com> To: Alexander H Duyck <alexander.duyck@...il.com>, netdev@...r.kernel.org Cc: davem@...emloft.net, kuba@...nel.org, edumazet@...gle.com, pabeni@...hat.com Subject: Re: [PATCH net-next v4 01/10] tsnep: Use spin_lock_bh for TX On 10.01.23 16:49, Alexander H Duyck wrote: > On Mon, 2023-01-09 at 20:15 +0100, Gerhard Engleder wrote: >> TX processing is done only within BH context. Therefore, _irqsafe >> variant is not necessary. >> >> Signed-off-by: Gerhard Engleder <gerhard@...leder-embedded.com> > > Rather than reducing the context of this why not drop it completely? It > doesn't look like you are running with the NETIF_F_LLTX flag set so > from what I can tell it looks like you are taking the Tx lock in the > xmit path. So Tx queues are protected with the Tx queue lock at the > netdev level via the HARD_TX_LOCK macro. > > Since it is already being used in the Tx path to protect multiple > access you could probably just look at getting rid of it entirely. > > The only caveat you would need to watch out for is a race between the > cleaning and transmitting which can be addressed via a few barriers > like what was done in the intel drivers via something like the > __ixgbe_maybe_stop_tx function and the logic to wake the queue in the > clean function. I know these barriers in the intel drivers. But I chose to use a lock like the microchip driver to be on the safe side rather than having a fully optimized driver. > Alternatively if you really feel you need this in the non-xmit path > functions you could just drop the lock and instead use __netif_tx_lock > for those spots that are accessing the queue outside the normal > transmit path. Ok, I will work on that. One of your suggestions will be done. Gerhard
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