Date: Tue, 5 Jul 2016 17:59:04 +0000 (UTC) From: Mark Johnston <markj@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r302346 - head/sys/kern Message-ID: <201607051759.u65Hx4qg079332@repo.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: markj Date: Tue Jul 5 17:59:04 2016 New Revision: 302346 URL: https://svnweb.freebsd.org/changeset/base/302346 Log: Ensure that spinlock sections are balanced even after a panic. vpanic() uses spinlock_enter() to disable interrupts before dumping core. However, when the scheduler is stopped and INVARIANTS is not configured, thread_lock() does not acquire a spinlock section, while thread_unlock() releases one. This can result in interrupts staying enabled while the kernel dumps core, complicating post-mortem analysis of the crash. Approved by: re (gjb) MFC after: 1 week Sponsored by: EMC / Isilon Storage Division Modified: head/sys/kern/kern_mutex.c Modified: head/sys/kern/kern_mutex.c ============================================================================== --- head/sys/kern/kern_mutex.c Tue Jul 5 16:37:01 2016 (r302345) +++ head/sys/kern/kern_mutex.c Tue Jul 5 17:59:04 2016 (r302346) @@ -657,8 +657,15 @@ thread_lock_flags_(struct thread *td, in i = 0; tid = (uintptr_t)curthread; - if (SCHEDULER_STOPPED()) + if (SCHEDULER_STOPPED()) { + /* + * Ensure that spinlock sections are balanced even when the + * scheduler is stopped, since we may otherwise inadvertently + * re-enable interrupts while dumping core. + */ + spinlock_enter(); return; + } #ifdef KDTRACE_HOOKS spin_time -= lockstat_nsecs(&td->td_lock->lock_object);
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201607051759.u65Hx4qg079332>