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Better fix than my previous commit:

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in exit1(), make sure the p_klist is empty after sending NOTE_EXIT.
The process won't report fork() or execve() and won't be able to handle
NOTE_SIGNAL knotes anyway.
This fixes some race conditions with do_tdsignal() calling knote() while
the process is exiting.

Reported by:	Stefan Farfeleder <stefan@fafoe.narf.at>
MFC after:	1 week
This commit is contained in:
cognet 2003-11-14 18:49:01 +00:00
parent 0cfaf203b6
commit 690de3f7ac
2 changed files with 9 additions and 8 deletions
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10
sys/kern/kern_event.c
View File

@ -218,7 +218,8 @@ filt_procattach(struct knote *kn)
kn->kn_flags &= ~EV_FLAG1; kn->kn_flags &= ~EV_FLAG1;
} }
SLIST_INSERT_HEAD(&p->p_klist, kn, kn_selnext); if (immediate == 0)
SLIST_INSERT_HEAD(&p->p_klist, kn, kn_selnext);
/* /*
* Immediately activate any exit notes if the target process is a * Immediately activate any exit notes if the target process is a
@ -279,13 +280,6 @@ filt_proc(struct knote *kn, long hint)
return (1); return (1);
} }
/*
* Process will already be reported as gone.
* Do not report anything else, as the knote will be destroyed soon.
*/
if (kn->kn_status & KN_DETACHED)
return (0);
/* /*
* process forked, and user wants to track the new process, * process forked, and user wants to track the new process,
* so attach a new knote to it, and immediately report an * so attach a new knote to it, and immediately report an

7
sys/kern/kern_exit.c
View File

@ -436,6 +436,13 @@ exit1(struct thread *td, int rv)
* Notify interested parties of our demise. * Notify interested parties of our demise.
*/ */
KNOTE(&p->p_klist, NOTE_EXIT); KNOTE(&p->p_klist, NOTE_EXIT);
/*
* Just delete all entries in the p_klist. At this point we won't
* report any more events, and there are nasty race conditions that
* can beat us if we don't.
*/
while (SLIST_FIRST(&p->p_klist))
SLIST_REMOVE_HEAD(&p->p_klist, kn_selnext);
/* /*
* Notify parent that we're gone. If parent has the PS_NOCLDWAIT * Notify parent that we're gone. If parent has the PS_NOCLDWAIT