Author: markj
Date: Thu May 11 17:03:45 2017
New Revision: 318191
URL: https://svnweb.freebsd.org/changeset/base/318191
Log:
Let ptracestop() suspend threads sleeping in an SBDRY section.
When a thread enters ptracestop(), for example because it had received
SIGSTOP from ptrace(PT_ATTACH), it attempts to suspend other threads in
the same process. In the case of a thread sleeping interruptibly in an
SBDRY section, sig_suspend_threads() must wake the thread and allow it to
reach the user-mode boundary. However, sig_suspend_threads() would
erroneously avoid waking up such threads, resulting in an apparent hang.
Reviewed by: kib
Tested by: pho
MFC after: 2 weeks
Sponsored by: Dell EMC Isilon
Modified:
head/sys/kern/kern_sig.c
Modified: head/sys/kern/kern_sig.c
==============================================================================
--- head/sys/kern/kern_sig.c Thu May 11 16:37:29 2017 (r318190)
+++ head/sys/kern/kern_sig.c Thu May 11 17:03:45 2017 (r318191)
@@ -2477,6 +2477,7 @@ sig_suspend_threads(struct thread *td, s
PROC_LOCK_ASSERT(p, MA_OWNED);
PROC_SLOCK_ASSERT(p, MA_OWNED);
+ MPASS(sending || td == curthread);
wakeup_swapper = 0;
FOREACH_THREAD_IN_PROC(p, td2) {
@@ -2493,10 +2494,9 @@ sig_suspend_threads(struct thread *td, s
*/
KASSERT(!TD_IS_SUSPENDED(td2),
("thread with deferred stops suspended"));
- if (TD_SBDRY_INTR(td2) && sending) {
+ if (TD_SBDRY_INTR(td2))
wakeup_swapper |= sleepq_abort(td2,
TD_SBDRY_ERRNO(td2));
- }
} else if (!TD_IS_SUSPENDED(td2)) {
thread_suspend_one(td2);
}
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