netdev - Re: [PATCH] netxen: Fix a sleep-in-atomic bug in netxen_nic_pci_mem_access

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Message-ID: <87d19xooo0.fsf@purkki.adurom.net>
Date:   Wed, 21 Jun 2017 09:11:43 +0300
From:   Kalle Valo <kvalo@...eaurora.org>
To:     David Miller <davem@...emloft.net>
Cc:     baijiaju1990@....com, manish.chopra@...ium.com,
        rahul.verma@...ium.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] netxen: Fix a sleep-in-atomic bug in netxen_nic_pci_mem_access_direct

David Miller <davem@...emloft.net> writes:

> From: Jia-Ju Bai <baijiaju1990@....com>
> Date: Mon, 19 Jun 2017 10:48:53 +0800
>
>> The driver may sleep under a spin lock, and the function call path is:
>> netxen_nic_pci_mem_access_direct (acquire the lock by spin_lock)
>>   ioremap --> may sleep
>> 
>> To fix it, the lock is released before "ioremap", and the lock is 
>> acquired again after this function.
>> 
>> Signed-off-by: Jia-Ju Bai <baijiaju1990@....com>
>
> This style of change you are making is really starting to be a
> problem.
>
> You can't just drop locks like this, especially without explaining
> why it's ok, and why the mutual exclusion this code was trying to
> achieve is still going to be OK afterwards.
>
> In fact, I see zero analysis of the locking situation here, why
> it was needed in the first place, and why your change is OK in
> that context.
>
> Any locking change is delicate, and you must put the greatest of
> care and consideration into it.
>
> Just putting "unlock/lock" around the sleeping operation shows a
> very low level of consideration for the implications of the change
> you are making.
>
> This isn't like making whitespace fixes, sorry...

We already tried to explain this to Jia-Ju during review of a wireless
patch:

https://patchwork.kernel.org/patch/9756585/

Jia-Ju, you should listen to feedback. If you continue submitting random
patches like this makes it hard for maintainers to trust your patches
anymore.

-- 
Kalle Valo