Sysrq trigger mechanism for kexec based crashdumps

PATCH New Hariprasad Nellitheertha 1 participant 1 message Mar 31, 2005

Subsystems (2)

Documentation Char and misc drivers

lore

Share & tools

lore

Hariprasad Nellitheertha

author

2005-03-31 10:50 UTC #0 lore raw

PATCH 1/1 Sysrq trigger mechanism for kexec based crashdumps

Hi Andrew,

The following patch adds a sysrq-trigger mechanism for kexec based crashdumps. Alt-Sysrq-c triggers a kexec based crashdump. Please include this along with the crashdumps patches in the -mm tree.

Thanks and Regards, Hari

Signed-off-by Hariprasad Nellitheertha <[email protected]>

---

 linux-2.6.12-rc1-mm3-1M-hari/Documentation/sysrq.txt |    5 +++
 linux-2.6.12-rc1-mm3-1M-hari/drivers/char/sysrq.c    |   24 +++++++++++++++++--
 2 files changed, 27 insertions(+), 2 deletions(-)

Documentation/sysrq.txt renamed from Documentation/sysrq.txt~crashdump-sysrq-trigger +5 -0

diff -puN Documentation/sysrq.txt~crashdump-sysrq-trigger Documentation/sysrq.txt
@@ -72,6 +72,8 @@ On all -  write a character to /proc/sys
 'b'     - Will immediately reboot the system without syncing or unmounting
           your disks.
 
+'c'	- Will perform a kexec reboot in order to take a crashdump.
+
 'o'     - Will shut your system off (if configured and supported).
 
 's'     - Will attempt to sync all mounted filesystems.

@@ -122,6 +124,9 @@ useful when you want to exit a program t
 re'B'oot is good when you're unable to shut down. But you should also 'S'ync
 and 'U'mount first.
 
+'C'rashdump can be used to manually trigger a crashdump when the system is hung.
+The kernel needs to have been built with CONFIG_KEXEC enabled.
+
 'S'ync is great when your system is locked up, it allows you to sync your
 disks and will certainly lessen the chance of data loss and fscking. Note
 that the sync hasn't taken place until you see the "OK" and "Done" appear

drivers/char/sysrq.c renamed from drivers/char/sysrq.c~crashdump-sysrq-trigger +22 -2

diff -puN drivers/char/sysrq.c~crashdump-sysrq-trigger drivers/char/sysrq.c
@@ -34,6 +34,7 @@
 #include <linux/swap.h>
 #include <linux/spinlock.h>
 #include <linux/vt_kern.h>
+#include <linux/kexec.h>
 
 #include <asm/ptrace.h>
 #ifdef CONFIG_KGDB_SYSRQ

@@ -112,6 +113,21 @@ static struct sysrq_key_op sysrq_unraw_o
 };
 #endif /* CONFIG_VT */
 
+#ifdef CONFIG_KEXEC
+/* crashdump sysrq handler */
+static void sysrq_handle_crashdump(int key, struct pt_regs *pt_regs,
+				struct tty_struct *tty)
+{
+	crash_kexec();
+}
+static struct sysrq_key_op sysrq_crashdump_op = {
+	.handler	= sysrq_handle_crashdump,
+	.help_msg	= "Crashdump",
+	.action_msg	= "Trigger a crashdump",
+	.enable_mask	= SYSRQ_ENABLE_DUMP,
+};
+#endif
+
 /* reboot sysrq handler */
 static void sysrq_handle_reboot(int key, struct pt_regs *pt_regs,
 				struct tty_struct *tty)

@@ -285,8 +301,12 @@ static struct sysrq_key_op *sysrq_key_ta
 		 it is handled specially on the sparc
 		 and will never arrive */
 /* b */	&sysrq_reboot_op,
-/* c */ NULL,
-/* d */	NULL,
+#ifdef CONFIG_KEXEC
+/* c */ &sysrq_crashdump_op,
+#else
+/* c */	NULL,
+#endif
+/* d */ NULL,
 /* e */	&sysrq_term_op,
 /* f */	&sysrq_moom_op,
 /* g */	GDB_OP,