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Subject[PATCH] X86: reboot-notify additions
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From: Cliff Wickman <cpw@sgi.com>

X86 reboot-notify additions.

This patch adds scans of the "reboot_notifier_list" callback chain in
a three other places where the kernel is being stopped and/or restarted.

Adds calls to blocking_notifier_call_chain() in:
crash_kexec(), emergency_restart(), sys_kexec_load()

In the crash_kexec() and emergency_restart() cases it is indicated to the
called-back function that the system is not in a sane state, so that
it can avoid taking a lock or some such potentially blocking action.

These callbacks are important to a partition system. The stopped kernel needs
to inform other partitions of their need to disconnect (stop sharing memory).

Diffed against 2.6.26-rc6

Signed-off-by: Cliff Wickman <cpw@sgi.com>
---
include/linux/notifier.h | 4 ++++
kernel/kexec.c | 5 +++++
kernel/sys.c | 1 +
3 files changed, 10 insertions(+)
Index: linux/include/linux/notifier.h
===================================================================
--- linux.orig/include/linux/notifier.h
+++ linux/include/linux/notifier.h
@@ -202,6 +202,10 @@ static inline int notifier_to_errno(int
#define SYS_RESTART SYS_DOWN
#define SYS_HALT 0x0002 /* Notify of system halt */
#define SYS_POWER_OFF 0x0003 /* Notify of system power off */
+#define SYS_INSANE 0x0004 /* Notify of system error/panic/oops */
+/* For the SYS_INSANE case, no locks should be taken by the called-back
+ * function. The kernel is ready for an immediate reboot.
+ */

#define NETLINK_URELEASE 0x0001 /* Unicast netlink socket released */

Index: linux/kernel/kexec.c
===================================================================
--- linux.orig/kernel/kexec.c
+++ linux/kernel/kexec.c
@@ -1001,6 +1001,9 @@ asmlinkage long sys_kexec_load(unsigned
if (result)
goto out;
}
+
+ blocking_notifier_call_chain(&reboot_notifier_list, SYS_RESTART, NULL);
+
/* Install the new kernel, and Uninstall the old */
image = xchg(dest_image, image);

@@ -1068,6 +1071,8 @@ void crash_kexec(struct pt_regs *regs)
if (!locked) {
if (kexec_crash_image) {
struct pt_regs fixed_regs;
+ blocking_notifier_call_chain(&reboot_notifier_list,
+ SYS_INSANE, NULL);
crash_setup_regs(&fixed_regs, regs);
crash_save_vmcoreinfo();
machine_crash_shutdown(&fixed_regs);
Index: linux/kernel/sys.c
===================================================================
--- linux.orig/kernel/sys.c
+++ linux/kernel/sys.c
@@ -270,6 +270,7 @@ out_unlock:
*/
void emergency_restart(void)
{
+ blocking_notifier_call_chain(&reboot_notifier_list, SYS_INSANE, NULL);
machine_emergency_restart();
}
EXPORT_SYMBOL_GPL(emergency_restart);

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