git: c35f527ed115 - main - sx: unset td_wantedlock around going to sleep

The branch main has been updated by mjg:

URL: https://cgit.FreeBSD.org/src/commit/?id=c35f527ed115b792463d30c7d3c8904e435caead

commit c35f527ed115b792463d30c7d3c8904e435caead
Author:     Mateusz Guzik <mjg@FreeBSD.org>
AuthorDate: 2023-10-23 17:22:12 +0000
Commit:     Mateusz Guzik <mjg@FreeBSD.org>
CommitDate: 2023-10-23 17:22:12 +0000

    sx: unset td_wantedlock around going to sleep
    
    Otherwise it can crash in sleepq_wait_sig -> sleepq_catch_signals ->
    sig_ast_checksusp -> thread_suspend_check due to a mutex acquire.
    
    Reported by:    pho
    Sponsored by:   Rubicon Communications, LLC ("Netgate")
---
 sys/kern/kern_sx.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/sys/kern/kern_sx.c b/sys/kern/kern_sx.c
index bc8a1214689f..455ae165e328 100644
--- a/sys/kern/kern_sx.c
+++ b/sys/kern/kern_sx.c
@@ -854,10 +854,17 @@ retry_sleepq:
 		sleepq_add(&sx->lock_object, NULL, sx->lock_object.lo_name,
 		    SLEEPQ_SX | ((opts & SX_INTERRUPTIBLE) ?
 		    SLEEPQ_INTERRUPTIBLE : 0), SQ_EXCLUSIVE_QUEUE);
+		/*
+		 * Hack: this can land in thread_suspend_check which will
+		 * conditionally take a mutex, tripping over an assert if a
+		 * lock we are waiting for is set.
+		 */
+		THREAD_CONTENTION_DONE(&sx->lock_object);
 		if (!(opts & SX_INTERRUPTIBLE))
 			sleepq_wait(&sx->lock_object, 0);
 		else
 			error = sleepq_wait_sig(&sx->lock_object, 0);
+		THREAD_CONTENTION_DONE(&sx->lock_object);
 #ifdef KDTRACE_HOOKS
 		sleep_time += lockstat_nsecs(&sx->lock_object);
 		sleep_cnt++;
@@ -1209,10 +1216,17 @@ retry_sleepq:
 		sleepq_add(&sx->lock_object, NULL, sx->lock_object.lo_name,
 		    SLEEPQ_SX | ((opts & SX_INTERRUPTIBLE) ?
 		    SLEEPQ_INTERRUPTIBLE : 0), SQ_SHARED_QUEUE);
+		/*
+		 * Hack: this can land in thread_suspend_check which will
+		 * conditionally take a mutex, tripping over an assert if a
+		 * lock we are waiting for is set.
+		 */
+		THREAD_CONTENTION_DONE(&sx->lock_object);
 		if (!(opts & SX_INTERRUPTIBLE))
 			sleepq_wait(&sx->lock_object, 0);
 		else
 			error = sleepq_wait_sig(&sx->lock_object, 0);
+		THREAD_CONTENDS_ON_LOCK(&sx->lock_object);
 #ifdef KDTRACE_HOOKS
 		sleep_time += lockstat_nsecs(&sx->lock_object);
 		sleep_cnt++;