On 11/25/20 11:45 AM, Yann Ylavic wrote:
> On Wed, Nov 25, 2020 at 10:20 AM Ruediger Pluem <rpl...@apache.org> wrote:
>>
>> On 11/24/20 10:12 PM, yla...@apache.org wrote:
>>> Author: ylavic
>>> Date: Tue Nov 24 21:12:37 2020
>>> New Revision: 1883801
>>>
>>> URL: http://svn.apache.org/viewvc?rev=1883801&view=rev
>>> Log:
>>> apr_pools: follow up to r1883750 and r1883800.
>>>
>>> After r1883800, the mutex of a pool in APR_POOL_DEBUG can't be NULL, so
>>> remove useless NULL checks around locking.
>>
>> I am struggling a bit to see when the mutex could have been NULL before
>> r1883800.
>
> It could have been NULL because apr_pool_create_ex_debug() was adding
> the pool to the parent's children list before creating the mutex.
> In this window, apr_pool_walk_tree() (like apr_pool_find() starting
> from the global_pool) could have found the pool with its NULL mutex
> and walked it unlocked.
Ahh. Thanks for explaining. I did not consider this short period of time and
that another thread doing
apr_pool_walk_tree could then hit the NULL mutex.
Regards
Rüdiger
