linux-kernel - Re: [PATCH] n_gsm: Fix write handling for zero bytes written

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Message-ID: <34dd61d2-01c3-dcc1-21bd-494eb90759ac@kernel.org>
Date:   Wed, 19 Aug 2020 08:19:58 +0200
From:   Jiri Slaby <jirislaby@...nel.org>
To:     Tony Lindgren <tony@...mide.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Gregory CLEMENT <gregory.clement@...tlin.com>,
        linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH] n_gsm: Fix write handling for zero bytes written

On 18. 08. 20, 12:47, Tony Lindgren wrote:
> * Jiri Slaby <jirislaby@...nel.org> [200818 10:14]:
>> On 18. 08. 20, 11:56, Tony Lindgren wrote:
>>> Hi,
>>>
>>> * Jiri Slaby <jirislaby@...nel.org> [200818 08:24]:
>>>> On 17. 08. 20, 15:54, Tony Lindgren wrote:
>>>>> If write returns zero we currently end up removing the message
>>>>> from the queue. Instead of removing the message, we want to just
>>>>> break out of the loop just like we already do for error codes.
>>>>
>>>> When exactly does the only writer (gsmld_output) return zero for
>>>> non-zero len parameter?
>>>
>>> I ran into this when testing with the WIP serial core PM runtime
>>> changes from Andy Shevchenko earlier. If there are also other
>>> cases where we have serial drivers return 0, I don't know about
>>> them.
>>
>> Sorry, I don't understand: my gsmld_output() ignores the return value
>> from drivers' write and returns something greater than zero or a
>> negative error. What tree/SHA do you run?
> 
> Oh right, good catch. I also had my WIP serdev-ngsm patches applied
> that uses gsm_serdev_output() and returns the bytes written. Andy's
> patches do not touch n_gsm.c.
> 
> Hmm sounds like we should also start returning value also from
> gsmld_output()? Any objections to making that change?

No objections here.

thanks,
-- 
js
suse labs