POSIX mq_receive NULL Priority

[Daniel Hellstrom]

Hello All,

Joel, thanks for CC:ing me.

The Gaisler RCC has this problem since we're still on 4.10.1. There are a couple of patches from 4.10.1 to 4.10.2, and I have it on my TODO to update our RCC release to 4.10.2. Vincent, I will try to 
find time in the coming weeks to rebase RCC to 4.10.2, in the meantime you can apply the patch(es) manually or by using the RCC Git repository and then rebuild the kernel yourself. If you have further 
questions about RCC you can mail support at gaisler.com.

Regards,
Daniel


On 03/18/2013 04:58 PM, Joel Sherrill wrote:
> On 3/18/2013 10:34 AM, Vincent Galbo wrote:
>>
>> Hello,
>>
>> I am not sure if this bug is common knowledge or not, but I figured I would report my findings.
>>
> I don't know it can be called common  knowledge because I didn't
> even remember it. :) The logs mention PR 1890 and PR 1895.
>
> But I committed the fix on 2011-08-21 to the head
>
> http://git.rtems.org/rtems/commit/cpukit/posix/src/mqueuerecvsupp.c?id=e5ca6593f7c7b543481147ca7f87696ecc821c06
>
> And to the 4.10 branch on 2011-09-01
>
> http://git.rtems.org/rtems/commit/cpukit/posix/src/mqueuerecvsupp.c?h=4.10&id=a1bfb335c0cc274513e144da46e203bff29e000b
>
> Is there a newer Gaisler version? cc'ing Daniel Hellstrom for feedback.
>
> And thank you for reporting this again. This time we got an easy solution.
>
>> I am working with RTEMS-4.10-1.2.7 on a UT699 LEON3. I received my RTEMS source from http://www.gaisler.com/anonftp/rcc/src/ .
>>
>> I have been using the function mq_receive to pass messages between POSIX threads (http://linux.die.net/man/3/mq_receive). Many manual pages explain that the fourth parameter, *msg_prio, can be left 
>> NULL if you do not care about the message priority. During some testing, I noticed that my mkprom2 boot loader was becoming corrupted. I determined that the mq_receive call was overriding my memory 
>> location 0. This was due to passing NULL into the priority parameter value. The mq_receive function must not check for NULL, and places the priority of the received message into whatever memory 
>> location is placed in the msg_prio parameter. My current work around is to pass in a dummy variable for the priority parameter.
>>
>> Vincent Galbo
>>
>
>
> -- 
> Joel Sherrill, Ph.D.             Director of Research & Development
> joel.sherrill at OARcorp.com         On-Line Applications Research
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