linux-kernel - Re: [KJ] Re: [PATCH] bugfix GFP_KERNEL -> GFP_ATOMIC in spin_locked region

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Message-ID: <87ejkqe51t.fsf@wanadoo.fr>
Date:	Tue, 05 Jun 2007 18:31:42 +0200
From:	Yoann Padioleau <padator@...adoo.fr>
To:	Oliver Neukum <oneukum@...e.de>
Cc:	Yoann Padioleau <padator@...adoo.fr>,
	kernel-janitors@...ts.osdl.org, linux-kernel@...r.kernel.org
Subject: Re: [KJ] Re: [PATCH] bugfix GFP_KERNEL -> GFP_ATOMIC in spin_locked region

Oliver Neukum <oneukum@...e.de> writes:

> Am Dienstag, 5. Juni 2007 13:05 schrieb Yoann Padioleau:
>> Ok. Do you have a preference on the format ?  a <file>:<line> format  ?
>> 
>> Is there a place that gathered all those implicit programming rules 
>> (that copy_from_user must not be called inside a spinlock, etc) so that
>> I can translate them in a script for our tool.
>
> How much C does your tool understand? 

The tool understands almost all the C language but the analysis we do
for the moment are intra-procedural so when we look for 
 spin_lock();
 ...
 copy_from_user();

it can detect cases and code paths only when the two function calls
are in the same function. It could be extended but it would require to
do a full analysis of the kernel source. Maybe if some functions of
the library have an attribute in their prototype in the .h such as

 __might_sleep copy_from_user(); 

it could help.

> You might basically
> test for code paths that go to "might_sleep()"

Ok, thanks. If you know other implicit programming rules,
I would be glad to know them, or if you know places
where thus rules are written.

BTW at one point I think the Linux community were using advanced
static analysis tools such as the one made by Dawson Engler (now
Coverity). The communitty have stopped using such tools ? Isn't the
role of sparse to detect bugs such as the dangerous copy_from_user()
inside spinlocked region ?

>
> 	Regards
> 		Oliver
>
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> Kernel-janitors mailing list
> Kernel-janitors@...ts.linux-foundation.org
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