Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

[linux-2.6-microblaze.git] / kernel / kexec_core.c

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 11b64a6..c823f30 100644 (file)
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -853,7 +853,12 @@ struct kimage *kexec_image;
 struct kimage *kexec_crash_image;
 int kexec_load_disabled;
 
-void crash_kexec(struct pt_regs *regs)
+/*
+ * No panic_cpu check version of crash_kexec().  This function is called
+ * only when panic_cpu holds the current CPU number; this is the only CPU
+ * which processes crash_kexec routines.
+ */
+void __crash_kexec(struct pt_regs *regs)
 {
        /* Take the kexec_mutex here to prevent sys_kexec_load
         * running on one cpu from replacing the crash kernel
@@ -876,6 +881,29 @@ void crash_kexec(struct pt_regs *regs)
        }
 }
 
+void crash_kexec(struct pt_regs *regs)
+{
+       int old_cpu, this_cpu;
+
+       /*
+        * Only one CPU is allowed to execute the crash_kexec() code as with
+        * panic().  Otherwise parallel calls of panic() and crash_kexec()
+        * may stop each other.  To exclude them, we use panic_cpu here too.
+        */
+       this_cpu = raw_smp_processor_id();
+       old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
+       if (old_cpu == PANIC_CPU_INVALID) {
+               /* This is the 1st CPU which comes here, so go ahead. */
+               __crash_kexec(regs);
+
+               /*
+                * Reset panic_cpu to allow another panic()/crash_kexec()
+                * call.
+                */
+               atomic_set(&panic_cpu, PANIC_CPU_INVALID);
+       }
+}
+
 size_t crash_get_memory_size(void)
 {
        size_t size = 0;