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From:
Vitaliy Makkoveev <mvs@openbsd.org>
Subject:
sysctl(2): unlock KERN_SPLASSERT
To:
tech@openbsd.org
Date:
Sun, 29 Dec 2024 20:43:40 +0300

Download raw body.

Thread
`splassert_ctl' is atomically accessed integer which accessed lockless
for a long time.

Index: sys/arch/alpha/include/intr.h
===================================================================
RCS file: /cvs/src/sys/arch/alpha/include/intr.h,v
diff -u -p -r1.50 intr.h
--- sys/arch/alpha/include/intr.h	17 May 2024 20:07:33 -0000	1.50
+++ sys/arch/alpha/include/intr.h	29 Dec 2024 17:16:16 -0000
@@ -147,6 +147,9 @@ void intr_barrier(void *);
 
 /* SPL asserts */
 #ifdef DIAGNOSTIC
+
+#include <sys/atomic.h>
+
 /*
  * Although this function is implemented in MI code, it must be in this MD
  * header because we don't want this header to include MI includes.
@@ -156,7 +159,7 @@ extern int splassert_ctl;
 void splassert_check(int, const char *);
 #define	splassert(__wantipl)						\
 	do {								\
-		if (splassert_ctl > 0) {				\
+		if (atomic_load_int(&splassert_ctl) > 0) {		\
 			splassert_check(__wantipl, __func__);		\
 		}							\
 	} while (0)
Index: sys/arch/amd64/include/intr.h
===================================================================
RCS file: /cvs/src/sys/arch/amd64/include/intr.h,v
diff -u -p -r1.34 intr.h
--- sys/arch/amd64/include/intr.h	26 May 2024 13:37:31 -0000	1.34
+++ sys/arch/amd64/include/intr.h	29 Dec 2024 17:16:16 -0000
@@ -152,6 +152,9 @@ void softintr(int);
 
 /* SPL asserts */
 #ifdef DIAGNOSTIC
+
+#include <sys/atomic.h>
+
 /*
  * Although this function is implemented in MI code, it must be in this MD
  * header because we don't want this header to include MI includes.
@@ -160,7 +163,7 @@ void splassert_fail(int, int, const char
 extern int splassert_ctl;
 void splassert_check(int, const char *);
 #define splassert(__wantipl) do {			\
-	if (splassert_ctl > 0) {			\
+	if (atomic_load_int(&splassert_ctl) > 0) {	\
 		splassert_check(__wantipl, __func__);	\
 	}						\
 } while (0)
Index: sys/arch/arm64/include/intr.h
===================================================================
RCS file: /cvs/src/sys/arch/arm64/include/intr.h,v
diff -u -p -r1.23 intr.h
--- sys/arch/arm64/include/intr.h	14 Oct 2024 10:08:13 -0000	1.23
+++ sys/arch/arm64/include/intr.h	29 Dec 2024 17:16:16 -0000
@@ -199,6 +199,9 @@ extern void (*intr_send_ipi_func)(struct
 #define ARM_IPI_HALT	2
 
 #ifdef DIAGNOSTIC
+
+#include <sys/atomic.h>
+
 /*
  * Although this function is implemented in MI code, it must be in this MD
  * header because we don't want this header to include MI includes.
@@ -207,7 +210,7 @@ void splassert_fail(int, int, const char
 extern int splassert_ctl;
 void arm_splassert_check(int, const char *);
 #define splassert(__wantipl) do {				\
-	if (splassert_ctl > 0) {				\
+	if (atomic_load_int(&splassert_ctl) > 0) {		\
 		arm_splassert_check(__wantipl, __func__);	\
 	}							\
 } while (0)
Index: sys/arch/armv7/include/intr.h
===================================================================
RCS file: /cvs/src/sys/arch/armv7/include/intr.h,v
diff -u -p -r1.15 intr.h
--- sys/arch/armv7/include/intr.h	14 Oct 2024 10:08:13 -0000	1.15
+++ sys/arch/armv7/include/intr.h	29 Dec 2024 17:16:16 -0000
@@ -202,6 +202,9 @@ extern void (*intr_send_ipi_func)(struct
 #define ARM_IPI_DDB	1
 
 #ifdef DIAGNOSTIC
+
+#include <sys/atomic.h>
+
 /*
  * Although this function is implemented in MI code, it must be in this MD
  * header because we don't want this header to include MI includes.
@@ -210,8 +213,8 @@ void splassert_fail(int, int, const char
 extern int splassert_ctl;
 void arm_splassert_check(int, const char *);
 #define splassert(__wantipl) do {                               \
-	if (splassert_ctl > 0) {                                \
-		arm_splassert_check(__wantipl, __func__);    \
+	if (atomic_load_int(&splassert_ctl) > 0) {              \
+		arm_splassert_check(__wantipl, __func__);       \
 	}                                                       \
 } while (0)
 #define splsoftassert(wantipl) splassert(wantipl)
Index: sys/arch/hppa/include/intr.h
===================================================================
RCS file: /cvs/src/sys/arch/hppa/include/intr.h,v
diff -u -p -r1.44 intr.h
--- sys/arch/hppa/include/intr.h	13 Jan 2018 15:18:11 -0000	1.44
+++ sys/arch/hppa/include/intr.h	29 Dec 2024 17:16:16 -0000
@@ -71,11 +71,14 @@
 extern volatile u_long imask[NIPL];
 
 #ifdef DIAGNOSTIC
+
+#include <sys/atomic.h>
+
 void splassert_fail(int, int, const char *);
 extern int splassert_ctl;
 void splassert_check(int, const char *);
 #define splassert(__wantipl) do {			\
-	if (splassert_ctl > 0) {			\
+	if (atomic_load_int(&splassert_ctl) > 0) {	\
 		splassert_check(__wantipl, __func__);	\
 	}						\
 } while (0)
Index: sys/arch/i386/include/intr.h
===================================================================
RCS file: /cvs/src/sys/arch/i386/include/intr.h,v
diff -u -p -r1.50 intr.h
--- sys/arch/i386/include/intr.h	26 May 2024 13:37:32 -0000	1.50
+++ sys/arch/i386/include/intr.h	29 Dec 2024 17:16:16 -0000
@@ -64,6 +64,9 @@ extern void softintr(int);
 
 /* SPL asserts */
 #ifdef DIAGNOSTIC
+
+#include <sys/atomic.h>
+
 /*
  * Although this function is implemented in MI code, it must be in this MD
  * header because we don't want this header to include MI includes.
@@ -72,7 +75,7 @@ void splassert_fail(int, int, const char
 extern int splassert_ctl;
 void splassert_check(int, const char *);
 #define splassert(__wantipl) do {			\
-	if (splassert_ctl > 0) {			\
+	if (atomic_load_int(&splassert_ctl) > 0) {	\
 		splassert_check(__wantipl, __func__);	\
 	}						\
 } while (0)
Index: sys/arch/landisk/include/intr.h
===================================================================
RCS file: /cvs/src/sys/arch/landisk/include/intr.h,v
diff -u -p -r1.14 intr.h
--- sys/arch/landisk/include/intr.h	20 Aug 2018 15:02:07 -0000	1.14
+++ sys/arch/landisk/include/intr.h	29 Dec 2024 17:16:16 -0000
@@ -66,6 +66,9 @@
 #define	splx(x)			_cpu_intr_resume(x)
 
 #ifdef DIAGNOSTIC
+
+#include <sys/atomic.h>
+
 /*
  * Although this function is implemented in MI code, it must be in this MD
  * header because we don't want this header to include MI includes.
@@ -75,7 +78,7 @@ extern int splassert_ctl;
 void splassert_check(int, const char *);
 #define	splassert(__wantipl) \
 do {									\
-	if (splassert_ctl > 0) {					\
+	if (atomic_load_int(&splassert_ctl) > 0) {			\
 		splassert_check(__wantipl, __func__);			\
 	}								\
 } while (0)
Index: sys/arch/loongson/include/intr.h
===================================================================
RCS file: /cvs/src/sys/arch/loongson/include/intr.h,v
diff -u -p -r1.18 intr.h
--- sys/arch/loongson/include/intr.h	5 Sep 2019 05:31:38 -0000	1.18
+++ sys/arch/loongson/include/intr.h	29 Dec 2024 17:16:16 -0000
@@ -129,6 +129,9 @@ void	 softintr_schedule(void *);
 void	splinit(void);
 
 #ifdef DIAGNOSTIC
+
+#include <sys/atomic.h>
+
 /*
  * Although this function is implemented in MI code, it must be in this MD
  * header because we don't want this header to include MI includes.
@@ -137,7 +140,7 @@ void splassert_fail(int, int, const char
 extern int splassert_ctl;
 void splassert_check(int, const char *);
 #define	splassert(__wantipl) do {				\
-	if (splassert_ctl > 0) {				\
+	if (atomic_load_int(&splassert_ctl) > 0) {		\
 		splassert_check(__wantipl, __func__);		\
 	}							\
 } while (0)
Index: sys/arch/m88k/include/intr.h
===================================================================
RCS file: /cvs/src/sys/arch/m88k/include/intr.h,v
diff -u -p -r1.14 intr.h
--- sys/arch/m88k/include/intr.h	20 Aug 2018 15:02:07 -0000	1.14
+++ sys/arch/m88k/include/intr.h	29 Dec 2024 17:16:16 -0000
@@ -72,6 +72,9 @@ int	spl0(void);
 
 /* SPL asserts */
 #ifdef DIAGNOSTIC
+
+#include <sys/atomic.h>
+
 /*
  * Although this function is implemented in MI code, it must be in this MD
  * header because we don't want this header to include MI includes.
@@ -80,7 +83,7 @@ void splassert_fail(int, int, const char
 extern int splassert_ctl;
 void splassert_check(int, const char *);
 #define splassert(__wantipl) do {			\
-	if (splassert_ctl > 0) {			\
+	if (atomic_load_int(&splassert_ctl) > 0) {	\
 		splassert_check(__wantipl, __func__);	\
 	}						\
 } while (0)
Index: sys/arch/octeon/include/intr.h
===================================================================
RCS file: /cvs/src/sys/arch/octeon/include/intr.h,v
diff -u -p -r1.22 intr.h
--- sys/arch/octeon/include/intr.h	5 Sep 2019 05:31:38 -0000	1.22
+++ sys/arch/octeon/include/intr.h	29 Dec 2024 17:16:16 -0000
@@ -128,6 +128,9 @@ void	 softintr_schedule(void *);
 void	splinit(void);
 
 #ifdef DIAGNOSTIC
+
+#include <sys/atomic.h>
+
 /*
  * Although this function is implemented in MI code, it must be in this MD
  * header because we don't want this header to include MI includes.
@@ -136,7 +139,7 @@ void splassert_fail(int, int, const char
 extern int splassert_ctl;
 void splassert_check(int, const char *);
 #define	splassert(__wantipl) do {				\
-	if (splassert_ctl > 0) {				\
+	if (atomic_load_int(&splassert_ctl) > 0) {		\
 		splassert_check(__wantipl, __func__);		\
 	}							\
 } while (0)
Index: sys/arch/powerpc/include/intr.h
===================================================================
RCS file: /cvs/src/sys/arch/powerpc/include/intr.h,v
diff -u -p -r1.56 intr.h
--- sys/arch/powerpc/include/intr.h	20 Aug 2018 15:02:07 -0000	1.56
+++ sys/arch/powerpc/include/intr.h	29 Dec 2024 17:16:16 -0000
@@ -90,6 +90,9 @@ void do_pending_int(void);
 
 /* SPL asserts */
 #ifdef DIAGNOSTIC
+
+#include <sys/atomic.h>
+
 /*
  * Although this function is implemented in MI code, it must be in this MD
  * header because we don't want this header to include MI includes.
@@ -98,7 +101,7 @@ void splassert_fail(int, int, const char
 extern int splassert_ctl;
 void splassert_check(int, const char *);
 #define splassert(__wantipl) do {			\
-	if (splassert_ctl > 0) {			\
+	if (atomic_load_int(&splassert_ctl) > 0) {	\
 		splassert_check(__wantipl, __func__);	\
 	}						\
 } while (0)
Index: sys/arch/powerpc64/include/intr.h
===================================================================
RCS file: /cvs/src/sys/arch/powerpc64/include/intr.h,v
diff -u -p -r1.14 intr.h
--- sys/arch/powerpc64/include/intr.h	30 May 2021 15:06:53 -0000	1.14
+++ sys/arch/powerpc64/include/intr.h	29 Dec 2024 17:16:16 -0000
@@ -65,6 +65,9 @@ void	splx(int);
 #define splhigh()	splraise(IPL_HIGH)
 
 #ifdef DIAGNOSTIC
+
+#include <sys/atomic.h>
+
 /*
  * Although this function is implemented in MI code, it must be in this MD
  * header because we don't want this header to include MI includes.
@@ -73,7 +76,7 @@ void splassert_fail(int, int, const char
 extern int splassert_ctl;
 void splassert_check(int, const char *);
 #define splassert(__wantipl) do {			\
-	if (splassert_ctl > 0) {			\
+	if (atomic_load_int(&splassert_ctl) > 0) {	\
 		splassert_check(__wantipl, __func__);	\
 	}						\
 } while (0)
Index: sys/arch/riscv64/include/intr.h
===================================================================
RCS file: /cvs/src/sys/arch/riscv64/include/intr.h,v
diff -u -p -r1.8 intr.h
--- sys/arch/riscv64/include/intr.h	16 Oct 2024 02:32:27 -0000	1.8
+++ sys/arch/riscv64/include/intr.h	29 Dec 2024 17:16:16 -0000
@@ -207,6 +207,9 @@ void	 riscv_intr_cpu_enable(void);
 void	intr_send_ipi(struct cpu_info *, int);
 
 #ifdef DIAGNOSTIC
+
+#include <sys/atomic.h>
+
 /*
  * Although this function is implemented in MI code, it must be in this MD
  * header because we don't want this header to include MI includes.
@@ -215,7 +218,7 @@ void splassert_fail(int, int, const char
 extern int splassert_ctl;
 void riscv_splassert_check(int, const char *);
 #define splassert(__wantipl) do {				\
-	if (splassert_ctl > 0) {				\
+	if (atomic_load_int(&splassert_ctl) > 0) {		\
 		riscv_splassert_check(__wantipl, __func__);	\
 	}							\
 } while (0)
Index: sys/arch/sparc64/include/psl.h
===================================================================
RCS file: /cvs/src/sys/arch/sparc64/include/psl.h,v
diff -u -p -r1.37 psl.h
--- sys/arch/sparc64/include/psl.h	6 Nov 2024 07:11:14 -0000	1.37
+++ sys/arch/sparc64/include/psl.h	29 Dec 2024 17:16:16 -0000
@@ -205,6 +205,9 @@
 #if defined(_KERNEL) && !defined(_LOCORE)
 
 #ifdef DIAGNOSTIC
+
+#include <sys/atomic.h>
+
 /*
  * Although this function is implemented in MI code, it must be in this MD
  * header because we don't want this header to include MI includes.
@@ -213,7 +216,7 @@ void splassert_fail(int, int, const char
 extern int splassert_ctl;
 void splassert_check(int, const char *);
 #define splassert(__wantipl) do {			\
-	if (splassert_ctl > 0) {			\
+	if (atomic_load_int(&splassert_ctl) > 0) {	\
 		splassert_check(__wantipl, __func__);	\
 	}						\
 } while (0)
Index: sys/dev/ic/iosf.c
===================================================================
RCS file: /cvs/src/sys/dev/ic/iosf.c,v
diff -u -p -r1.2 iosf.c
--- sys/dev/ic/iosf.c	26 Jun 2024 01:40:49 -0000	1.2
+++ sys/dev/ic/iosf.c	29 Dec 2024 17:16:16 -0000
@@ -258,7 +258,7 @@ iosf_mbi_assert_punit_acquired(void)
 {
 	int s;
 
-	if (splassert_ctl == 0)
+	if (atomic_load_int(&splassert_ctl) == 0)
 		return;
 
 	s = rw_status(&iosf_lock);
Index: sys/kern/kern_sysctl.c
===================================================================
RCS file: /cvs/src/sys/kern/kern_sysctl.c,v
diff -u -p -r1.459 kern_sysctl.c
--- sys/kern/kern_sysctl.c	28 Dec 2024 20:34:05 -0000	1.459
+++ sys/kern/kern_sysctl.c	29 Dec 2024 17:16:17 -0000
@@ -614,6 +614,7 @@ kern_sysctl(int *name, u_int namelen, vo
 	case KERN_FSCALE:
 	case KERN_CCPU:
 	case KERN_NPROCS:
+	case KERN_SPLASSERT:
 	case KERN_WXABORT:
 	case KERN_NETLIVELOCKS:
 	case KERN_GLOBAL_PTRACE:
Index: sys/kern/subr_prf.c
===================================================================
RCS file: /cvs/src/sys/kern/subr_prf.c,v
diff -u -p -r1.106 subr_prf.c
--- sys/kern/subr_prf.c	14 Aug 2022 01:58:28 -0000	1.106
+++ sys/kern/subr_prf.c	29 Dec 2024 17:16:17 -0000
@@ -89,6 +89,11 @@ struct mutex kprintf_mutex =
     MUTEX_INITIALIZER_FLAGS(IPL_HIGH, "kprintf", MTX_NOWITNESS);
 
 /*
+ * Locks used to protect data:
+ *	a	atomic
+ */
+
+/*
  * globals
  */
 
@@ -119,9 +124,9 @@ int	db_console = 0;
  * panic on spl assertion failure?
  */
 #ifdef SPLASSERT_WATCH
-int splassert_ctl = 3;
+int splassert_ctl = 3;		/* [a] */
 #else
-int splassert_ctl = 1;
+int splassert_ctl = 1;		/* [a] */
 #endif
 
 /*
@@ -199,7 +204,7 @@ panic(const char *fmt, ...)
 		bootopt |= RB_NOSYNC;
 
 	/* do not trigger assertions, we know that we are inconsistent */
-	splassert_ctl = 0;
+	atomic_store_int(&splassert_ctl, 0);
 
 #ifdef BOOT_QUIET
 	printf_flags |= TOCONS;	/* make sure we see kernel printf output */
@@ -243,7 +248,7 @@ splassert_fail(int wantipl, int haveipl,
 		return;
 
 	printf("splassert: %s: want %d have %d\n", func, wantipl, haveipl);
-	switch (splassert_ctl) {
+	switch (atomic_load_int(&splassert_ctl)) {
 	case 1:
 		break;
 	case 2:
Index: sys/kern/uipc_socket2.c
===================================================================
RCS file: /cvs/src/sys/kern/uipc_socket2.c,v
diff -u -p -r1.161 uipc_socket2.c
--- sys/kern/uipc_socket2.c	26 Dec 2024 12:16:17 -0000	1.161
+++ sys/kern/uipc_socket2.c	29 Dec 2024 17:16:17 -0000
@@ -460,7 +460,7 @@ soassertlocked(struct socket *so)
 		if (rw_status(&netlock) == RW_READ) {
 			NET_ASSERT_LOCKED();
 
-			if (splassert_ctl > 0 &&
+			if (atomic_load_int(&splassert_ctl) > 0 &&
 			    rw_status(&so->so_lock) != RW_WRITE)
 				splassert_fail(0, RW_WRITE, __func__);
 		} else
@@ -503,7 +503,8 @@ void
 sbmtxassertlocked(struct socket *so, struct sockbuf *sb)
 {
 	if (sb->sb_flags & SB_MTXLOCK) {
-		if (splassert_ctl > 0 && mtx_owned(&sb->sb_mtx) == 0)
+		if (atomic_load_int(&splassert_ctl) > 0 &&
+		    mtx_owned(&sb->sb_mtx) == 0)
 			splassert_fail(0, RW_WRITE, __func__);
 	} else
 		soassertlocked(so);
Index: sys/sys/systm.h
===================================================================
RCS file: /cvs/src/sys/sys/systm.h,v
diff -u -p -r1.171 systm.h
--- sys/sys/systm.h	28 May 2024 12:50:23 -0000	1.171
+++ sys/sys/systm.h	29 Dec 2024 17:16:17 -0000
@@ -347,21 +347,22 @@ extern struct rwlock netlock;
 #define	NET_ASSERT_UNLOCKED()						\
 do {									\
 	int _s = rw_status(&netlock);					\
-	if ((splassert_ctl > 0) && (_s == RW_WRITE))			\
+	if ((atomic_load_int(&splassert_ctl) > 0) && (_s == RW_WRITE))	\
 		splassert_fail(0, RW_WRITE, __func__);			\
 } while (0)
 
 #define	NET_ASSERT_LOCKED()						\
 do {									\
 	int _s = rw_status(&netlock);					\
-	if ((splassert_ctl > 0) && (_s != RW_WRITE && _s != RW_READ))	\
+	if ((atomic_load_int(&splassert_ctl) > 0) &&			\
+	    (_s != RW_WRITE && _s != RW_READ))	\
 		splassert_fail(RW_READ, _s, __func__);			\
 } while (0)
 
 #define	NET_ASSERT_LOCKED_EXCLUSIVE()					\
 do {									\
 	int _s = rw_status(&netlock);					\
-	if ((splassert_ctl > 0) && (_s != RW_WRITE))			\
+	if ((atomic_load_int(&splassert_ctl) > 0) && (_s != RW_WRITE))	\
 		splassert_fail(RW_WRITE, _s, __func__);			\
 } while (0)