From: David Miller <davem@davemloft.net>
To: joyce.ooi@intel.com
Cc: thor.thayer@linux.intel.com, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, dalon.westergreen@intel.com,
ley.foon.tan@intel.com, chin.liang.see@intel.com,
dinh.nguyen@intel.com
Subject: Re: [PATCHv2 01/10] net: eth: altera: tse_start_xmit ignores tx_buffer call response
Date: Mon, 04 May 2020 10:39:35 -0700 (PDT) [thread overview]
Message-ID: <20200504.103935.1584665284135386530.davem@davemloft.net> (raw)
In-Reply-To: <20200504082558.112627-2-joyce.ooi@intel.com>
From: Joyce Ooi <joyce.ooi@intel.com>
Date: Mon, 4 May 2020 16:25:49 +0800
> The return from tx_buffer call in tse_start_xmit is
> inapropriately ignored. tse_buffer calls should return
> 0 for success or NETDEV_TX_BUSY. tse_start_xmit should
> return not report a successful transmit when the tse_buffer
> call returns an error condition.
From driver.txt:
====================
1) The ndo_start_xmit method must not return NETDEV_TX_BUSY under
any normal circumstances. It is considered a hard error unless
there is no way your device can tell ahead of time when it's
transmit function will become busy.
====================
The problem is that when you return this error code, something has
to trigger restarting the transmit queue to start sending packets
to your device again. The usual mechanism is waking the transmit
queue, but it's obviously already awake since your transmit routine
is being called. Therefore nothing will reliably restart the queue
when you return this error code.
The best thing to do honestly is to drop the packet and return
NETDEV_TX_OK, meanwhile bumping a statistic counter to record this
event.
next prev parent reply other threads:[~2020-05-04 17:39 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-04 8:25 [PATCHv2 00/10] net: eth: altera: tse: Add PTP and mSGDMA prefetcher Joyce Ooi
2020-05-04 8:25 ` [PATCHv2 01/10] net: eth: altera: tse_start_xmit ignores tx_buffer call response Joyce Ooi
2020-05-04 17:39 ` David Miller [this message]
2020-05-05 9:27 ` Ooi, Joyce
2020-05-04 8:25 ` [PATCHv2 02/10] net: eth: altera: set rx and tx ring size before init_dma call Joyce Ooi
2020-05-04 8:25 ` [PATCHv2 03/10] net: eth: altera: fix altera_dmaops declaration Joyce Ooi
2020-05-04 8:25 ` [PATCHv2 04/10] net: eth: altera: add optional function to start tx dma Joyce Ooi
2020-05-04 8:25 ` [PATCHv2 05/10] net: eth: altera: Move common functions to altera_utils Joyce Ooi
2020-05-04 8:25 ` [PATCHv2 06/10] net: eth: altera: Add missing identifier names to function declarations Joyce Ooi
2020-05-04 8:25 ` [PATCHv2 07/10] net: eth: altera: change tx functions to type netdev_tx_t Joyce Ooi
2020-05-04 8:25 ` [PATCHv2 08/10] net: eth: altera: add support for ptp and timestamping Joyce Ooi
2020-05-04 16:52 ` Richard Cochran
2020-05-04 8:25 ` [PATCHv2 09/10] net: eth: altera: add msgdma prefetcher Joyce Ooi
2020-05-04 8:25 ` [PATCHv2 10/10] net: eth: altera: update devicetree bindings documentation Joyce Ooi
2020-05-12 22:52 ` Rob Herring
2020-05-13 12:00 ` Ooi, Joyce
2020-05-13 13:00 ` Ooi, Joyce
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