11 files changed, 9 insertions, 39 deletions

diff --git a/sys/alpha/alpha/mp_machdep.c b/sys/alpha/alpha/mp_machdep.c
index 33741f0abce2..e12a68a71328 100644
--- a/sys/alpha/alpha/mp_machdep.c
+++ b/sys/alpha/alpha/mp_machdep.c
@@ -281,14 +281,11 @@ globaldata_find(int cpuid)
 /* lock around the MP rendezvous */
 static struct mtx smp_rv_mtx;
 
-/* only 1 CPU can panic at a time :) */
-struct mtx panic_mtx;
 
 static void
 init_locks(void)
 {
 	mtx_init(&smp_rv_mtx, "smp rendezvous", MTX_SPIN);
-	mtx_init(&panic_mtx, "panic", MTX_DEF);
 }
 
 void
diff --git a/sys/amd64/amd64/mp_machdep.c b/sys/amd64/amd64/mp_machdep.c
index 66ab9f3f6839..7bc0a320d028 100644
--- a/sys/amd64/amd64/mp_machdep.c
+++ b/sys/amd64/amd64/mp_machdep.c
@@ -357,9 +357,6 @@ struct mtx		com_mtx;
 /* lock around the MP rendezvous */
 static struct mtx	smp_rv_mtx;
 
-/* only 1 CPU can panic at a time :) */
-struct mtx		panic_mtx;
-
 static void
 init_locks(void)
 {
@@ -371,7 +368,6 @@ init_locks(void)
 	mtx_init(&mcount_mtx, "mcount", MTX_DEF);
 
 	mtx_init(&smp_rv_mtx, "smp rendezvous", MTX_SPIN);
-	mtx_init(&panic_mtx, "panic", MTX_DEF);
 
 #ifdef USE_COMLOCK
 	mtx_init(&com_mtx, "com", MTX_SPIN);
diff --git a/sys/amd64/amd64/mptable.c b/sys/amd64/amd64/mptable.c
index 66ab9f3f6839..7bc0a320d028 100644
--- a/sys/amd64/amd64/mptable.c
+++ b/sys/amd64/amd64/mptable.c
@@ -357,9 +357,6 @@ struct mtx		com_mtx;
 /* lock around the MP rendezvous */
 static struct mtx	smp_rv_mtx;
 
-/* only 1 CPU can panic at a time :) */
-struct mtx		panic_mtx;
-
 static void
 init_locks(void)
 {
@@ -371,7 +368,6 @@ init_locks(void)
 	mtx_init(&mcount_mtx, "mcount", MTX_DEF);
 
 	mtx_init(&smp_rv_mtx, "smp rendezvous", MTX_SPIN);
-	mtx_init(&panic_mtx, "panic", MTX_DEF);
 
 #ifdef USE_COMLOCK
 	mtx_init(&com_mtx, "com", MTX_SPIN);
diff --git a/sys/amd64/include/mptable.h b/sys/amd64/include/mptable.h
index 66ab9f3f6839..7bc0a320d028 100644
--- a/sys/amd64/include/mptable.h
+++ b/sys/amd64/include/mptable.h
@@ -357,9 +357,6 @@ struct mtx		com_mtx;
 /* lock around the MP rendezvous */
 static struct mtx	smp_rv_mtx;
 
-/* only 1 CPU can panic at a time :) */
-struct mtx		panic_mtx;
-
 static void
 init_locks(void)
 {
@@ -371,7 +368,6 @@ init_locks(void)
 	mtx_init(&mcount_mtx, "mcount", MTX_DEF);
 
 	mtx_init(&smp_rv_mtx, "smp rendezvous", MTX_SPIN);
-	mtx_init(&panic_mtx, "panic", MTX_DEF);
 
 #ifdef USE_COMLOCK
 	mtx_init(&com_mtx, "com", MTX_SPIN);
diff --git a/sys/i386/i386/mp_machdep.c b/sys/i386/i386/mp_machdep.c
index 66ab9f3f6839..7bc0a320d028 100644
--- a/sys/i386/i386/mp_machdep.c
+++ b/sys/i386/i386/mp_machdep.c
@@ -357,9 +357,6 @@ struct mtx		com_mtx;
 /* lock around the MP rendezvous */
 static struct mtx	smp_rv_mtx;
 
-/* only 1 CPU can panic at a time :) */
-struct mtx		panic_mtx;
-
 static void
 init_locks(void)
 {
@@ -371,7 +368,6 @@ init_locks(void)
 	mtx_init(&mcount_mtx, "mcount", MTX_DEF);
 
 	mtx_init(&smp_rv_mtx, "smp rendezvous", MTX_SPIN);
-	mtx_init(&panic_mtx, "panic", MTX_DEF);
 
 #ifdef USE_COMLOCK
 	mtx_init(&com_mtx, "com", MTX_SPIN);
diff --git a/sys/i386/i386/mptable.c b/sys/i386/i386/mptable.c
index 66ab9f3f6839..7bc0a320d028 100644
--- a/sys/i386/i386/mptable.c
+++ b/sys/i386/i386/mptable.c
@@ -357,9 +357,6 @@ struct mtx		com_mtx;
 /* lock around the MP rendezvous */
 static struct mtx	smp_rv_mtx;
 
-/* only 1 CPU can panic at a time :) */
-struct mtx		panic_mtx;
-
 static void
 init_locks(void)
 {
@@ -371,7 +368,6 @@ init_locks(void)
 	mtx_init(&mcount_mtx, "mcount", MTX_DEF);
 
 	mtx_init(&smp_rv_mtx, "smp rendezvous", MTX_SPIN);
-	mtx_init(&panic_mtx, "panic", MTX_DEF);
 
 #ifdef USE_COMLOCK
 	mtx_init(&com_mtx, "com", MTX_SPIN);
diff --git a/sys/i386/include/mptable.h b/sys/i386/include/mptable.h
index 66ab9f3f6839..7bc0a320d028 100644
--- a/sys/i386/include/mptable.h
+++ b/sys/i386/include/mptable.h
@@ -357,9 +357,6 @@ struct mtx		com_mtx;
 /* lock around the MP rendezvous */
 static struct mtx	smp_rv_mtx;
 
-/* only 1 CPU can panic at a time :) */
-struct mtx		panic_mtx;
-
 static void
 init_locks(void)
 {
@@ -371,7 +368,6 @@ init_locks(void)
 	mtx_init(&mcount_mtx, "mcount", MTX_DEF);
 
 	mtx_init(&smp_rv_mtx, "smp rendezvous", MTX_SPIN);
-	mtx_init(&panic_mtx, "panic", MTX_DEF);
 
 #ifdef USE_COMLOCK
 	mtx_init(&com_mtx, "com", MTX_SPIN);
diff --git a/sys/kern/kern_shutdown.c b/sys/kern/kern_shutdown.c
index ad79fdcbbb79..55c4ba47d973 100644
--- a/sys/kern/kern_shutdown.c
+++ b/sys/kern/kern_shutdown.c
@@ -548,6 +548,10 @@ dumpstatus(vm_offset_t addr, long count)
 	return 0;
 }
 
+#ifdef SMP
+static u_int panic_cpu = NOCPU;
+#endif
+
 /*
  * Panic is called on unresolvable fatal errors.  It prints "panic: mesg",
  * and then reboots.  If we are called twice, then we avoid trying to sync
@@ -562,7 +566,11 @@ panic(const char *fmt, ...)
 
 #ifdef SMP
 	/* Only 1 CPU can panic at a time */
-	mtx_lock(&panic_mtx);
+	if (panic_cpu != PCPU_GET(cpuid) &&
+	    atomic_cmpset_int(&panic_cpu, NOCPU, PCPU_GET(cpuid)) == 0) {
+		for (;;)
+			; /* nothing */
+	}
 #endif
 
 	bootopt = RB_AUTOBOOT | RB_DUMP;
diff --git a/sys/kern/subr_smp.c b/sys/kern/subr_smp.c
index 66ab9f3f6839..7bc0a320d028 100644
--- a/sys/kern/subr_smp.c
+++ b/sys/kern/subr_smp.c
@@ -357,9 +357,6 @@ struct mtx		com_mtx;
 /* lock around the MP rendezvous */
 static struct mtx	smp_rv_mtx;
 
-/* only 1 CPU can panic at a time :) */
-struct mtx		panic_mtx;
-
 static void
 init_locks(void)
 {
@@ -371,7 +368,6 @@ init_locks(void)
 	mtx_init(&mcount_mtx, "mcount", MTX_DEF);
 
 	mtx_init(&smp_rv_mtx, "smp rendezvous", MTX_SPIN);
-	mtx_init(&panic_mtx, "panic", MTX_DEF);
 
 #ifdef USE_COMLOCK
 	mtx_init(&com_mtx, "com", MTX_SPIN);
diff --git a/sys/powerpc/powerpc/mp_machdep.c b/sys/powerpc/powerpc/mp_machdep.c
index 8ca5b047d5e3..e8c65f3104e5 100644
--- a/sys/powerpc/powerpc/mp_machdep.c
+++ b/sys/powerpc/powerpc/mp_machdep.c
@@ -232,15 +232,11 @@ globaldata_find(int cpuno)
 /* lock around the MP rendezvous */
 static struct mtx smp_rv_mtx;
 
-/* only 1 CPU can panic at a time :) */
-struct mtx panic_mtx;
-
 static void
 init_locks(void)
 {
 
 	mtx_init(&smp_rv_mtx, "smp rendezvous", MTX_SPIN);
-	mtx_init(&panic_mtx, "panic", MTX_DEF);
 }
 
 void
diff --git a/sys/sys/kernel.h b/sys/sys/kernel.h
index 3bcef6f1e173..443874f62816 100644
--- a/sys/sys/kernel.h
+++ b/sys/sys/kernel.h
@@ -81,9 +81,6 @@ extern int lbolt;			/* once a second sleep address */
 extern int tickdelta;
 extern long timedelta;
 
-/* global data in mp_machdep.c */
-extern struct mtx       panic_mtx;
-
 #endif /* _KERNEL */
 
 /*