lkml.org 
[lkml]   [2006]   [Jul]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
DateSat, 29 Jul 2006 10:37:04 +0100
FromRussell King <>
SubjectRe: [KJ] audit return code handling for kernel_thread [2/11]
On Fri, Jul 28, 2006 at 04:07:13PM -0400, nhorman@tuxdriver.com wrote:
> Audit/Cleanup of kernel_thread calls, specifically checking of return codes.
> Problems seemed to fall into 3 main categories:
>
> 1) callers of kernel_thread were inconsistent about meaning of a zero return
> code. Some callers considered a zero return code to mean success, others took
> it to mean failure. a zero return code, while not actually possible in the
> current implementation, should be considered a success (pid 0 is/should be
> valid). fixed all callers to treat zero return as success
>
> 2) caller of kernel_thread saved return code of kernel_thread for later use
> without ever checking its value. Callers who did this tended to assume a
> non-zero return was success, and would often wait for a completion queue to be
> woken up, implying that an error (negative return code) from kernel_thread could
> lead to deadlock. Repaired by checking return code at call time, and setting
> saved return code to zero in the event of an error.

This is inconsistent with your assertion that pid 0 "is/should be valid"
above. If you want '0' to mean "not valid" then it's not a valid return
value from kernel_thread() (and arguably that's true, since pid 0 is
permanently allocated to the idle thread.)

I don't particularly care whether you decide to that returning pid 0 from
kernel_thread is valid or not, just that your two points above are at least
consistent with each other.

--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 Serial core
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-07-29 11:39    [from the cache]
©2003-2010