linux-kernel - Re: [PATCH 0/4] ath10k: a few incorrect return handling fix-up

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Message-ID: <20141230194239.GA13655@opentech.at>
Date:	Tue, 30 Dec 2014 20:42:39 +0100
From:	Nicholas Mc Guire <der.herr@...r.at>
To:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
Cc:	Kalle Valo <kvalo@....qualcomm.com>,
	Michal Kazior <michal.kazior@...to.com>,
	Ben Greear <greearb@...delatech.com>,
	Chun-Yeow Yeoh <yeohchunyeow@...il.com>,
	Yanbo Li <yanbol@....qualcomm.com>, ath10k@...ts.infradead.org,
	linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/4] ath10k: a few incorrect return handling fix-up

On Tue, 30 Dec 2014, Sergei Shtylyov wrote:

> On 12/30/2014 09:28 PM, Nicholas Mc Guire wrote:
>
>>>> wait_for_completion_timeout does not return negative values so the tests
>>>> for <= 0 are not needed and the case differentiation in the error handling
>>>> path unnecessary.
>
>>>     I decided to verify your statement and I saw that it seems wrong.
>>> do_wait_for_common() can return -ERESTARTSYS and the return value gets
>>> returned by its callers unchanged.
>
>> the -ERESTARTSYS only can be returned if state matches but
>> wait_for_completion_timemout passes TASK_UNINTERRUPTIBLE
>> so signal_pending_state will return 0 and never negativ
>
>> my understanding of the callchain is:
>> wait_for_completion_timemout with TASK_UNINTERRUPTIBLE
>>    -> wait_for_common(...TASK_UNINTERRUPTIBLE)
>>      -> __wait_for_common(...TASK_UNINTERRUPTIBLE)
>>        -> do_wait_for_common(...TASK_UNINTERRUPTIBLE)
>>          -> signal_pending_state(TASK_UNINTERRUPTIBLE...)
>
>> static inline int signal_pending_state(long state, struct task_struct *p)
>> {
>>          if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
>>                  return 0;
>
>    Right. I didn't look into TASK_UNINTERRUPTIBLE thing before sending my mail.
>
>> so wait_for_completion_timemout should return 0 or 1 only
>
>    0 or the remaining time, to be precise.
>

yup - thanks for the confirmation!

>>>> patch was only compile tested x86_64_defconfig + CONFIG_ATH_CARDS=m
>>>> CONFIG_ATH10K=m
>
>>>> patch is against linux-next 3.19.0-rc1 -next-20141226
>
>>>     Rather patches. It would have been better to send one patch instead of
>>> 4 patches with the same name.
>
>> sorry for that - I had split it into separate patches as it was
>> in different files - giving them the same name of course was a bit
>> brain-dead.
>
>    You should have mentioned the modified files in the subject. But IMHO 
> it would be better to have just one patch.
>
resent as a single patch as v2

thx!
hofrat
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