[PATCH 4/23] Add emergency_restart()

When the kernel is working well and we want to restart cleanly
kernel_restart is the function to use.   But in many instances
the kernel wants to reboot when thing are expected to be working
very badly such as from panic or a software watchdog handler.

This patch adds the function emergency_restart() so that
callers can be clear what semantics they expect when calling
restart.  emergency_restart() is expected to be callable
from interrupt context and possibly reliable in even more
trying circumstances.

This is an initial generic implementation for all architectures.

Signed-off-by: Eric W. Biederman <[email protected]>
---

 include/asm-alpha/emergency-restart.h     |    6 ++++++
 include/asm-arm/emergency-restart.h       |    6 ++++++
 include/asm-arm26/emergency-restart.h     |    6 ++++++
 include/asm-cris/emergency-restart.h      |    6 ++++++
 include/asm-frv/emergency-restart.h       |    6 ++++++
 include/asm-generic/emergency-restart.h   |    9 +++++++++
 include/asm-h8300/emergency-restart.h     |    6 ++++++
 include/asm-i386/emergency-restart.h      |    6 ++++++
 include/asm-ia64/emergency-restart.h      |    6 ++++++
 include/asm-m32r/emergency-restart.h      |    6 ++++++
 include/asm-m68k/emergency-restart.h      |    6 ++++++
 include/asm-m68knommu/emergency-restart.h |    6 ++++++
 include/asm-mips/emergency-restart.h      |    6 ++++++
 include/asm-parisc/emergency-restart.h    |    6 ++++++
 include/asm-ppc/emergency-restart.h       |    6 ++++++
 include/asm-ppc64/emergency-restart.h     |    6 ++++++
 include/asm-s390/emergency-restart.h      |    6 ++++++
 include/asm-sh/emergency-restart.h        |    6 ++++++
 include/asm-sh64/emergency-restart.h      |    6 ++++++
 include/asm-sparc/emergency-restart.h     |    6 ++++++
 include/asm-sparc64/emergency-restart.h   |    6 ++++++
 include/asm-um/emergency-restart.h        |    6 ++++++
 include/asm-v850/emergency-restart.h      |    6 ++++++
 include/asm-x86_64/emergency-restart.h    |    6 ++++++
 include/asm-xtensa/emergency-restart.h    |    6 ++++++
 include/linux/reboot.h                    |    7 +++++++
 kernel/sys.c                              |    6 ++++++
 27 files changed, 166 insertions(+), 0 deletions(-)
 create mode 100644 include/asm-alpha/emergency-restart.h
 create mode 100644 include/asm-arm/emergency-restart.h
 create mode 100644 include/asm-arm26/emergency-restart.h
 create mode 100644 include/asm-cris/emergency-restart.h
 create mode 100644 include/asm-frv/emergency-restart.h
 create mode 100644 include/asm-generic/emergency-restart.h
 create mode 100644 include/asm-h8300/emergency-restart.h
 create mode 100644 include/asm-i386/emergency-restart.h
 create mode 100644 include/asm-ia64/emergency-restart.h
 create mode 100644 include/asm-m32r/emergency-restart.h
 create mode 100644 include/asm-m68k/emergency-restart.h
 create mode 100644 include/asm-m68knommu/emergency-restart.h
 create mode 100644 include/asm-mips/emergency-restart.h
 create mode 100644 include/asm-parisc/emergency-restart.h
 create mode 100644 include/asm-ppc/emergency-restart.h
 create mode 100644 include/asm-ppc64/emergency-restart.h
 create mode 100644 include/asm-s390/emergency-restart.h
 create mode 100644 include/asm-sh/emergency-restart.h
 create mode 100644 include/asm-sh64/emergency-restart.h
 create mode 100644 include/asm-sparc/emergency-restart.h
 create mode 100644 include/asm-sparc64/emergency-restart.h
 create mode 100644 include/asm-um/emergency-restart.h
 create mode 100644 include/asm-v850/emergency-restart.h
 create mode 100644 include/asm-x86_64/emergency-restart.h
 create mode 100644 include/asm-xtensa/emergency-restart.h

3d8ea7bd8df5d92589d8e02f45b979073c855848
diff --git a/include/asm-alpha/emergency-restart.h b/include/asm-alpha/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-alpha/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-arm/emergency-restart.h b/include/asm-arm/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-arm/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-arm26/emergency-restart.h b/include/asm-arm26/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-arm26/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-cris/emergency-restart.h b/include/asm-cris/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-cris/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-frv/emergency-restart.h b/include/asm-frv/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-frv/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-generic/emergency-restart.h b/include/asm-generic/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-generic/emergency-restart.h
@@ -0,0 +1,9 @@
+#ifndef _ASM_GENERIC_EMERGENCY_RESTART_H
+#define _ASM_GENERIC_EMERGENCY_RESTART_H
+
+static inline void machine_emergency_restart(void)
+{
+	machine_restart(NULL);
+}
+
+#endif /* _ASM_GENERIC_EMERGENCY_RESTART_H */
diff --git a/include/asm-h8300/emergency-restart.h b/include/asm-h8300/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-h8300/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-i386/emergency-restart.h b/include/asm-i386/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-i386/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-ia64/emergency-restart.h b/include/asm-ia64/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-ia64/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-m32r/emergency-restart.h b/include/asm-m32r/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-m32r/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-m68k/emergency-restart.h b/include/asm-m68k/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-m68k/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-m68knommu/emergency-restart.h b/include/asm-m68knommu/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-m68knommu/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-mips/emergency-restart.h b/include/asm-mips/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-mips/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-parisc/emergency-restart.h b/include/asm-parisc/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-parisc/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-ppc/emergency-restart.h b/include/asm-ppc/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-ppc/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-ppc64/emergency-restart.h b/include/asm-ppc64/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-ppc64/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-s390/emergency-restart.h b/include/asm-s390/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-s390/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-sh/emergency-restart.h b/include/asm-sh/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-sh/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-sh64/emergency-restart.h b/include/asm-sh64/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-sh64/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-sparc/emergency-restart.h b/include/asm-sparc/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-sparc/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-sparc64/emergency-restart.h b/include/asm-sparc64/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-sparc64/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-um/emergency-restart.h b/include/asm-um/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-um/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-v850/emergency-restart.h b/include/asm-v850/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-v850/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-x86_64/emergency-restart.h b/include/asm-x86_64/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-x86_64/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/asm-xtensa/emergency-restart.h b/include/asm-xtensa/emergency-restart.h
new file mode 100644
--- /dev/null
+++ b/include/asm-xtensa/emergency-restart.h
@@ -0,0 +1,6 @@
+#ifndef _ASM_EMERGENCY_RESTART_H
+#define _ASM_EMERGENCY_RESTART_H
+
+#include <asm-generic/emergency-restart.h>
+
+#endif /* _ASM_EMERGENCY_RESTART_H */
diff --git a/include/linux/reboot.h b/include/linux/reboot.h
--- a/include/linux/reboot.h
+++ b/include/linux/reboot.h
@@ -64,6 +64,13 @@ extern void kernel_halt(void);
 extern void kernel_power_off(void);
 extern void kernel_kexec(void);
 
+/*
+ * Emergency restart, callable from an interrupt handler.
+ */
+
+extern void emergency_restart(void);
+#include <asm/emergency-restart.h>
+
 #endif
 
 #endif /* _LINUX_REBOOT_H */
diff --git a/kernel/sys.c b/kernel/sys.c
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -361,6 +361,12 @@ out_unlock:
 	return retval;
 }
 
+void emergency_restart(void)
+{
+	machine_emergency_restart();
+}
+EXPORT_SYMBOL_GPL(emergency_restart);
+
 void kernel_restart(char *cmd)
 {
 	notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd);
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---

• Follow-Ups:
  • [PATCH 5/23] Fix the arguments to machine_restart on cris
    • From: [email protected] (Eric W. Biederman)

• References:
  • [PATCH 0/23] reboot-fixes
    • From: [email protected] (Eric W. Biederman)
  • [PATCH 1/23] Add missing device_suspsend(PMSG_FREEZE) calls.
    • From: [email protected] (Eric W. Biederman)
  • [PATCH 2/23] Refactor sys_reboot into reusable parts
    • From: [email protected] (Eric W. Biederman)
  • [PATCH 3/23] Make ctrl_alt_del call kernel_restart to get a proper reboot.
    • From: [email protected] (Eric W. Biederman)

• Prev by Date: [PATCH 2/23] Refactor sys_reboot into reusable parts
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