Giant Pushdown. Saved the worst P4 tree breakage for last.

    reboot() getpriority() setpriority() rtprio() osetrlimit() ogetrlimit()
    setrlimit() getrlimit() getrusage() getpid() getppid() getpgrp()
    getpgid() getsid() getgid() getegid() getgroups() setsid() setpgid()
    setuid() seteuid() setgid() setegid() setgroups() setreuid() setregid()
    setresuid() setresgid() getresuid() getresgid () __setugid() getlogin()
    setlogin() modnext() modfnext() modstat() modfind() kldload() kldunload()
    kldfind() kldnext() kldstat() kldfirstmod() kldsym() getdtablesize()
    dup2() dup() fcntl() close() ofstat() fstat() nfsstat() fpathconf()
    flock()

1 files changed, 28 insertions, 9 deletions

diff --git a/sys/kern/kern_shutdown.c b/sys/kern/kern_shutdown.c
index 1afa80f..90b3642 100644
--- a/sys/kern/kern_shutdown.c
+++ b/sys/kern/kern_shutdown.c
@@ -131,21 +131,23 @@ shutdown_conf(void *unused)
 
 SYSINIT(shutdown_conf, SI_SUB_INTRINSIC, SI_ORDER_ANY, shutdown_conf, NULL)
 
-/* ARGSUSED */
-
 /*
  * The system call that results in a reboot
+ *
+ * MPSAFE
  */
+/* ARGSUSED */
 int
 reboot(struct proc *p, struct reboot_args *uap)
 {
 	int error;
 
-	if ((error = suser(p)))
-		return (error);
-
-	boot(uap->opt);
-	return (0);
+	mtx_lock(&Giant);
+	if ((error = suser(p)) == 0) {
+		boot(uap->opt);
+	}
+	mtx_unlock(&Giant);
+	return (error);
 }
 
 /*
@@ -565,14 +567,27 @@ static u_int panic_cpu = NOCPU;
  * 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
  * the disks as this often leads to recursive panics.
+ *
+ * MPSAFE
  */
 void
 panic(const char *fmt, ...)
 {
 	int bootopt;
+	int holding_giant = 0;
 	va_list ap;
 	static char buf[256];
 
+#if 0
+	/*
+	 * We must hold Giant when entering a panic
+	 */
+	if (!mtx_owned(&Giant)) {
+		mtx_lock(&Giant);
+		holding_giant = 1;
+	}
+#endif
+
 #ifdef SMP
 	/*
 	 * We don't want multiple CPU's to panic at the same time, so we
@@ -580,11 +595,13 @@ panic(const char *fmt, ...)
 	 * panic_cpu if we are spinning in case the panic on the first
 	 * CPU is canceled.
 	 */
-	if (panic_cpu != PCPU_GET(cpuid))
+	if (panic_cpu != PCPU_GET(cpuid)) {
 		while (atomic_cmpset_int(&panic_cpu, NOCPU,
-		    PCPU_GET(cpuid)) == 0)
+		    PCPU_GET(cpuid)) == 0) {
 			while (panic_cpu != NOCPU)
 				; /* nothing */
+		}
+	}
 #endif
 
 	bootopt = RB_AUTOBOOT | RB_DUMP;
@@ -616,6 +633,8 @@ panic(const char *fmt, ...)
 #ifdef SMP
 		atomic_store_rel_int(&panic_cpu, NOCPU);
 #endif
+		if (holding_giant)
+			mtx_unlock(&Giant);
 		return;
 	}
 #endif