Messages in this thread Patch in this message | | | Date | Thu, 09 May 2002 14:27:00 -0500 | From | Dave McCracken <> | Subject | [PATCH 2.4] Thread group exit problem reappeared. |
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A long time ago there was thread group code that at exit time tried to reparent a task to another task in the thread group. I discovered a major race condition in this code, and submitted a patch that removed it. This patch was accepted in, I thin, 2.4.12. The code reappeared in 2.4.18, breaking applications that use thread groups.
As part of chasing this down, I figured out a way to remove the race condition while still preserving this behavior. I've attached a patch against 2.4.19-pre8 that fixes it.
Dave McCracken
====================================================================== Dave McCracken IBM Linux Base Kernel Team 1-512-838-3059 dmccr@us.ibm.com T/L 678-3059 --- linux-2.4.19-pre8/./kernel/exit.c Tue May 7 09:18:14 2002 +++ linux-2.4.19-pre8-reparent/./kernel/exit.c Tue May 7 10:01:56 2002 @@ -152,7 +152,7 @@ /* * When we die, we re-parent all our children. - * Try to give them to another thread in our process + * Try to give them to another thread in our thread * group, and if no such member exists, give it to * the global child reaper process (ie "init") */ @@ -162,8 +162,14 @@ read_lock(&tasklist_lock); - /* Next in our thread group */ - reaper = next_thread(father); + /* Next in our thread group, if they're not already exiting */ + reaper = father; + do { + reaper = next_thread(reaper); + if (!(reaper->flags & PF_EXITING)) + break; + } while (reaper != father); + if (reaper == father) reaper = child_reaper;
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