Re: [Xenomai-core] Racy pse51_mutex_check_init?

[Jan Kiszka <jan.kiszka@domain.hid>]

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Gilles Chanteperdrix wrote:
> Jan Kiszka wrote:
>> Hi Gilles,
>>
>> trying to understand the cb_read/write lock usage, some question came up
>> here: What prevents that the mutexq iteration in pse51_mutex_check_init
>> races against pse51_mutex_destroy_internal?
>>
>> If nothing, then I wonder if we actually have to iterate over the whole
>> queue to find out whether a given object has been initialized and
>> registered already or not. Can't this be encoded differently?
> 
> We actually iterate over the queue only if the magic happens to be
> correct, which is not the common case.

However, there remains a race window with other threads removing other
mutex objects in parallel, changing the queue - risking a kernel oops.
And that is what worries me. It's unlikely. but possible. It's unclean.

Jan


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