Date: Sat, 17 Aug 2013 17:02:43 +0000 (UTC) From: Bryan Venteicher <bryanv@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r254457 - head/sys/kern Message-ID: <201308171702.r7HH2hn4025712@svn.freebsd.org>
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Author: bryanv Date: Sat Aug 17 17:02:43 2013 New Revision: 254457 URL: http://svnweb.freebsd.org/changeset/base/254457 Log: Do not use potentially stale thread in kthread_add() When an existing process is provided, the thread selected to use to initialize the new thread could have exited and be reaped. Acquire the proc lock earlier to ensure the thread remains valid. Reviewed by: jhb, julian (previous version) MFC after: 3 days Modified: head/sys/kern/kern_kthread.c Modified: head/sys/kern/kern_kthread.c ============================================================================== --- head/sys/kern/kern_kthread.c Sat Aug 17 16:42:18 2013 (r254456) +++ head/sys/kern/kern_kthread.c Sat Aug 17 17:02:43 2013 (r254457) @@ -257,18 +257,17 @@ kthread_add(void (*func)(void *), void * panic("kthread_add called too soon"); /* If no process supplied, put it on proc0 */ - if (p == NULL) { + if (p == NULL) p = &proc0; - oldtd = &thread0; - } else { - oldtd = FIRST_THREAD_IN_PROC(p); - } /* Initialize our new td */ newtd = thread_alloc(pages); if (newtd == NULL) return (ENOMEM); + PROC_LOCK(p); + oldtd = FIRST_THREAD_IN_PROC(p); + bzero(&newtd->td_startzero, __rangeof(struct thread, td_startzero, td_endzero)); bcopy(&oldtd->td_startcopy, &newtd->td_startcopy, @@ -292,7 +291,6 @@ kthread_add(void (*func)(void *), void * newtd->td_ucred = crhold(p->p_ucred); /* this code almost the same as create_thread() in kern_thr.c */ - PROC_LOCK(p); p->p_flag |= P_HADTHREADS; thread_link(newtd, p); thread_lock(oldtd);
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