netdev - Re: [PATCH v4 2/4] can: kvaser_usb: Update error counters before exiting on OOM

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Message-ID: <54B922B3.1020608@pengutronix.de>
Date:	Fri, 16 Jan 2015 15:39:47 +0100
From:	Marc Kleine-Budde <mkl@...gutronix.de>
To:	"Ahmed S. Darwish" <darwish.07@...il.com>
CC:	Olivier Sobrie <olivier@...rie.be>,
	Oliver Hartkopp <socketcan@...tkopp.net>,
	Wolfgang Grandegger <wg@...ndegger.com>,
	"David S. Miller" <davem@...emloft.net>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Linux-CAN <linux-can@...r.kernel.org>,
	netdev <netdev@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>, andri.yngvason@...el.com
Subject: Re: [PATCH v4 2/4] can: kvaser_usb: Update error counters before
 exiting on OOM

On 01/12/2015 09:36 PM, Ahmed S. Darwish wrote:
> On Mon, Jan 12, 2015 at 12:09:32PM +0100, Marc Kleine-Budde wrote:
>> On 01/11/2015 09:15 PM, Ahmed S. Darwish wrote:
>>> From: Ahmed S. Darwish <ahmed.darwish@...eo.com>
>>>
>>> Let the error counters be more accurate in case of Out of
>>> Memory conditions.
>>
>> Please have a look at kvaser_usb_rx_error(), the whole state handling is
>> omitted in case of OOM.
>>
> 
> I see. Regarding kvaser_usb_rx_error(), would something like
> below patch be acceptable? 
> 
> Kindly note that separating recording interface state from
> error frame packet building leads to duplication of a good
> number of if-conditions. Meanwhile, it truly saves _all_
> of the possible state before any ENOMEM -- the correct thing
> to do.
> 
> Another solution was to allocate the can frame on the stack,
> and thus avoiding any code duplication. But this only leads
> to calls of "kvaser_usb_simple_msg_async", which can fail
> with -ENOMEM by itself, returning to the very same problem
> again. 
> 
> If the patch is acceptable, I'll rebase my USBCAN-II driver
> above it and re-submit the series (minus the merged patch).

Looks good from my point of view, stats and state are handled
independent of the error skb.

Andri can you have a look at the state handling itself?

Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
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