Date: Mon, 8 Feb 2016 23:11:23 +0000 (UTC) From: John Baldwin <jhb@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r295419 - head/sys/kern Message-ID: <201602082311.u18NBNXr074129@repo.freebsd.org>
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Author: jhb Date: Mon Feb 8 23:11:23 2016 New Revision: 295419 URL: https://svnweb.freebsd.org/changeset/base/295419 Log: Call kthread_exit() rather than kproc_exit() for a premature kthread exit. Kernel threads (and processes) are supposed to call kthread_exit() (or kproc_exit()) to terminate. However, the kernel includes a fallback in fork_exit() to force a kthread exit if a kernel thread's "main" routine returns. This fallback was added back when the kernel only had processes and was not updated to call kthread_exit() instead of kproc_exit() when threads were added to the kernel. This mistake was particular exciting when the errant thread belonged to proc0. Due to the missing P_KTHREAD flag the fallback did not kick in and instead tried to return to userland via whatever garbage was in the trapframe. With P_KTHREAD set it tried to terminate proc0 resulting in other amusements. PR: 204999 MFC after: 1 week Modified: head/sys/kern/kern_fork.c Modified: head/sys/kern/kern_fork.c ============================================================================== --- head/sys/kern/kern_fork.c Mon Feb 8 23:06:27 2016 (r295418) +++ head/sys/kern/kern_fork.c Mon Feb 8 23:11:23 2016 (r295419) @@ -1040,7 +1040,7 @@ fork_exit(void (*callout)(void *, struct if (p->p_flag & P_KTHREAD) { printf("Kernel thread \"%s\" (pid %d) exited prematurely.\n", td->td_name, p->p_pid); - kproc_exit(0); + kthread_exit(); } mtx_assert(&Giant, MA_NOTOWNED);
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