diff options
| author | Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com> | 2009-07-29 15:04:14 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-07-29 19:10:36 -0700 |
| commit | cab8bd3410d448279e3bd0fbf96d31db0bf770fa (patch) | |
| tree | 2ad9262b2c4d10cc705c8553015caff06a29de11 /drivers/char | |
| parent | f5a55efa140f5e9c9dd0f398fef54f20cdb74ec9 (diff) | |
| download | linux-cab8bd3410d448279e3bd0fbf96d31db0bf770fa.tar.gz | |
sysrq, kdump: make sysrq-c consistent
commit d6580a9f15238b87e618310c862231ae3f352d2d ("kexec: sysrq: simplify
sysrq-c handler") changed the behavior of sysrq-c to unconditional
dereference of NULL pointer. So in cases with CONFIG_KEXEC, where
crash_kexec() was directly called from sysrq-c before, now it can be said
that a step of "real oops" was inserted before starting kdump.
However, in contrast to oops via SysRq-c from keyboard which results in
panic due to in_interrupt(), oops via "echo c > /proc/sysrq-trigger" will
not become panic unless panic_on_oops=1. It means that even if dump is
properly configured to be taken on panic, the sysrq-c from proc interface
might not start crashdump while the sysrq-c from keyboard can start
crashdump. This confuses traditional users of kdump, i.e. people who
expect sysrq-c to do common behavior in both of the keyboard and proc
interface.
This patch brings the keyboard and proc interface behavior of sysrq-c in
line, by forcing panic_on_oops=1 before oops in sysrq-c handler.
And some updates in documentation are included, to clarify that there is
no longer dependency with CONFIG_KEXEC, and that now the system can just
crash by sysrq-c if no dump mechanism is configured.
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Ken'ichi Ohmichi <oomichi@mxs.nes.nec.co.jp>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Cc: Brayan Arraes <brayan@yack.com.br>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/char')
| -rw-r--r-- | drivers/char/sysrq.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/drivers/char/sysrq.c b/drivers/char/sysrq.c index 0db35857e4d8..5d7a02f63e1c 100644 --- a/drivers/char/sysrq.c +++ b/drivers/char/sysrq.c @@ -35,7 +35,6 @@ #include <linux/spinlock.h> #include <linux/vt_kern.h> #include <linux/workqueue.h> -#include <linux/kexec.h> #include <linux/hrtimer.h> #include <linux/oom.h> @@ -124,9 +123,12 @@ static struct sysrq_key_op sysrq_unraw_op = { static void sysrq_handle_crash(int key, struct tty_struct *tty) { char *killer = NULL; + + panic_on_oops = 1; /* force panic */ + wmb(); *killer = 1; } -static struct sysrq_key_op sysrq_crashdump_op = { +static struct sysrq_key_op sysrq_crash_op = { .handler = sysrq_handle_crash, .help_msg = "Crash", .action_msg = "Trigger a crash", @@ -401,7 +403,7 @@ static struct sysrq_key_op *sysrq_key_table[36] = { */ NULL, /* a */ &sysrq_reboot_op, /* b */ - &sysrq_crashdump_op, /* c & ibm_emac driver debug */ + &sysrq_crash_op, /* c & ibm_emac driver debug */ &sysrq_showlocks_op, /* d */ &sysrq_term_op, /* e */ &sysrq_moom_op, /* f */ |