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. For a short leaving pool, the pool could then have been cleared while a walker was accessing a child => boom! Regards; Yann.
