git: 0b17876c084f - stable/15 - ktrcsw(): should not be called when the thread is owning interlock or on sleepq

The branch stable/15 has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=0b17876c084fe49c34d3db842d4972debbfe3b01

commit 0b17876c084fe49c34d3db842d4972debbfe3b01
Author:     Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2026-01-22 21:46:01 +0000
Commit:     Konstantin Belousov <kib@FreeBSD.org>
CommitDate: 2026-02-06 03:43:00 +0000

    ktrcsw(): should not be called when the thread is owning interlock or on sleepq
    
    (cherry picked from commit 245157fd8a382c3989075789ee98582665f3b31d)
---
 sys/kern/kern_ktrace.c | 18 ++++++++++++++++--
 sys/kern/kern_synch.c  | 26 +++++++++++---------------
 sys/sys/ktrace.h       |  1 +
 3 files changed, 28 insertions(+), 17 deletions(-)

diff --git a/sys/kern/kern_ktrace.c b/sys/kern/kern_ktrace.c
index b58e69a3f38e..f3ee1c53fafd 100644
--- a/sys/kern/kern_ktrace.c
+++ b/sys/kern/kern_ktrace.c
@@ -838,8 +838,8 @@ ktrpsig(int sig, sig_t action, sigset_t *mask, int code)
 	ktrace_exit(td);
 }
 
-void
-ktrcsw(int out, int user, const char *wmesg)
+static void
+ktrcsw_impl(int out, int user, const char *wmesg, const struct timespec *tv)
 {
 	struct thread *td = curthread;
 	struct ktr_request *req;
@@ -854,6 +854,8 @@ ktrcsw(int out, int user, const char *wmesg)
 	kc = &req->ktr_data.ktr_csw;
 	kc->out = out;
 	kc->user = user;
+	if (tv != NULL)
+		req->ktr_header.ktr_time = *tv;
 	if (wmesg != NULL)
 		strlcpy(kc->wmesg, wmesg, sizeof(kc->wmesg));
 	else
@@ -862,6 +864,18 @@ ktrcsw(int out, int user, const char *wmesg)
 	ktrace_exit(td);
 }
 
+void
+ktrcsw(int out, int user, const char *wmesg)
+{
+	ktrcsw_impl(out, user, wmesg, NULL);
+}
+
+void
+ktrcsw_out(const struct timespec *tv, const char *wmesg)
+{
+	ktrcsw_impl(1, 0, wmesg, tv);
+}
+
 void
 ktrstruct(const char *name, const void *data, size_t datalen)
 {
diff --git a/sys/kern/kern_synch.c b/sys/kern/kern_synch.c
index 8e956324ee23..0ab0ccb3d05b 100644
--- a/sys/kern/kern_synch.c
+++ b/sys/kern/kern_synch.c
@@ -133,6 +133,7 @@ _sleep(const void *ident, struct lock_object *lock, int priority,
 {
 	struct thread *td __ktrace_used;
 	struct lock_class *class;
+	struct timespec sw_out_tv __ktrace_used;
 	uintptr_t lock_state;
 	int catch, pri, rval, sleepq_flags;
 	WITNESS_SAVE_DECL(lock_witness);
@@ -141,7 +142,7 @@ _sleep(const void *ident, struct lock_object *lock, int priority,
 	td = curthread;
 #ifdef KTRACE
 	if (KTRPOINT(td, KTR_CSW))
-		ktrcsw(1, 0, wmesg);
+		nanotime(&sw_out_tv);
 #endif
 	WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
 	    "Sleeping on \"%s\"", wmesg);
@@ -222,8 +223,10 @@ _sleep(const void *ident, struct lock_object *lock, int priority,
 		rval = 0;
 	}
 #ifdef KTRACE
-	if (KTRPOINT(td, KTR_CSW))
+	if (KTRPOINT(td, KTR_CSW)) {
+		ktrcsw_out(&sw_out_tv, wmesg);
 		ktrcsw(0, 0, wmesg);
+	}
 #endif
 	PICKUP_GIANT();
 	if (lock != NULL && lock != &Giant.lock_object && !(priority & PDROP)) {
@@ -239,6 +242,7 @@ msleep_spin_sbt(const void *ident, struct mtx *mtx, const char *wmesg,
     sbintime_t sbt, sbintime_t pr, int flags)
 {
 	struct thread *td __ktrace_used;
+	struct timespec sw_out_tv __ktrace_used;
 	int rval;
 	WITNESS_SAVE_DECL(mtx);
 
@@ -266,19 +270,9 @@ msleep_spin_sbt(const void *ident, struct mtx *mtx, const char *wmesg,
 	if (sbt != 0)
 		sleepq_set_timeout_sbt(ident, sbt, pr, flags);
 
-	/*
-	 * Can't call ktrace with any spin locks held so it can lock the
-	 * ktrace_mtx lock, and WITNESS_WARN considers it an error to hold
-	 * any spin lock.  Thus, we have to drop the sleepq spin lock while
-	 * we handle those requests.  This is safe since we have placed our
-	 * thread on the sleep queue already.
-	 */
 #ifdef KTRACE
-	if (KTRPOINT(td, KTR_CSW)) {
-		sleepq_release(ident);
-		ktrcsw(1, 0, wmesg);
-		sleepq_lock(ident);
-	}
+	if (KTRPOINT(td, KTR_CSW))
+		nanotime(&sw_out_tv);
 #endif
 #ifdef WITNESS
 	sleepq_release(ident);
@@ -293,8 +287,10 @@ msleep_spin_sbt(const void *ident, struct mtx *mtx, const char *wmesg,
 		rval = 0;
 	}
 #ifdef KTRACE
-	if (KTRPOINT(td, KTR_CSW))
+	if (KTRPOINT(td, KTR_CSW)) {
+		ktrcsw_out(&sw_out_tv, wmesg);
 		ktrcsw(0, 0, wmesg);
+	}
 #endif
 	PICKUP_GIANT();
 	mtx_lock_spin(mtx);
diff --git a/sys/sys/ktrace.h b/sys/sys/ktrace.h
index 822822a6ffe7..1ba5c84000b0 100644
--- a/sys/sys/ktrace.h
+++ b/sys/sys/ktrace.h
@@ -340,6 +340,7 @@ ktr_get_tracevp(struct proc *p, bool ref)
 void	ktr_io_params_free(struct ktr_io_params *);
 void	ktrnamei(const char *);
 void	ktrcsw(int, int, const char *);
+void	ktrcsw_out(const struct timespec *, const char *);
 void	ktrpsig(int, sig_t, sigset_t *, int);
 void	ktrfault(vm_offset_t, int);
 void	ktrfaultend(int);