Re: [PATCH] Reclaim _REENT_MP_P5S in _reclaim_reent

[Corinna Vinschen <vinschen@redhat.com>]

On Nov 17 08:17, Chris Johns wrote:
> On 16/11/2023 8:15 pm, Corinna Vinschen wrote:
> > On Nov 16 12:12, chrisj@rtems.org wrote:
> >> From: Chris Johns <chrisj@rtems.org>
> >>
> >> The change fixes a memory leak in threads that clean up using
> >> _reclaim_reent.
> >>
> >> RTEMS: Closes #4967
> >> ---
> >>  newlib/libc/reent/reent.c | 11 +++++++++++
> >>  1 file changed, 11 insertions(+)
> >>
> >> diff --git a/newlib/libc/reent/reent.c b/newlib/libc/reent/reent.c
> >> index db80ca06e..6bb271b9a 100644
> >> --- a/newlib/libc/reent/reent.c
> >> +++ b/newlib/libc/reent/reent.c
> >> @@ -59,6 +59,17 @@ _reclaim_reent (struct _reent *ptr)
> >>  	}
> >>        if (_REENT_MP_RESULT(ptr))
> >>  	_free_r (ptr, _REENT_MP_RESULT(ptr));
> >> +      if (_REENT_MP_P5S(ptr))
> >> +        {
> >> +         struct _Bigint *thisone, *nextone;
> >> +         nextone = _REENT_MP_P5S(ptr);
> >> +         while (nextone)
> >> +           {
> >> +             thisone = nextone;
> >> +             nextone = nextone->_next;
> >> +             _free_r (ptr, thisone);
> >> +           }
> >> +       }
> > 
> > The p5s data is allocated using Balloc, so the pointers are in freelist
> > and should already be free'd at this point, starting at line 42.
> 
> Yes however P5S blocks allocated by Balloc via i2b are not passed to Bfree.

Aaah, right, it really never does.

> > Please explain what happens and why free'ing the freelist is not
> > sufficient in this case, preferredly as part of the commit message.
> 
> Yes good idea. How about:
> 
> The _REENT_MP_P5S blocks are allocated using Balloc via i2b and linked in the
> pow5mult call. As a result these blocks are not on the freelist managed by the
> Bfree call. This change fixes a memory leak in threads that clean up using
> _reclaim_reent.

Yeah, sounds good.  Please resend with this commit message.


Thanks,
Corinna