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

Yoann Padioleau
2007-06-05T16:34:24Z

Oliver Neukum <oneukum@suse.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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