The patch titled
panic, vt: do not force oops output when panic_timeout < 0
has been added to the -mm tree. Its filename is
panic-vt-do-not-force-oops-output-when-panic_timeout-0.patch
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------------------------------------------------------
Subject: panic, vt: do not force oops output when panic_timeout < 0
From: Mandeep Singh Baines <msb@xxxxxxxxxxxx>
Don't force output if you intend to reboot immediately.
In this patch, I'm disabling the functionality enabled by
vc->vc_panic_force_write if panic_timeout < 0 (i.e. no timeout).
vc_panic_force_write is only enabled for fb video consoles if the
FBINFO_CAN_FORCE_OUTPUT flag is set.
For our application, we're using ram_oops to preserved the panic in
memory. We want to reliably, and as fast as possible, machine_restart.
The vc_panic_force_write flag results in a bunch of graphics driver code
to be invoked which slows down restart and decreases reliability. Since
we're already storing the panic in RAM and are going to reboot
immediately, there is no benefit in mode switching back to the vc in order
to display the panic output. The log buffer will get flushed by the
console_unblank() call so remote management consoles should see all
output.
Signed-off-by: Mandeep Singh Baines <msb@xxxxxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Olaf Hering <olaf@xxxxxxxxx>
Cc: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx>
Cc: Dave Airlie <airlied@xxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxx>
Acked-by: Alan Cox <alan@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/vt_kern.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN include/linux/vt_kern.h~panic-vt-do-not-force-oops-output-when-panic_timeout-0 include/linux/vt_kern.h
--- a/include/linux/vt_kern.h~panic-vt-do-not-force-oops-output-when-panic_timeout-0
+++ a/include/linux/vt_kern.h
@@ -137,7 +137,7 @@ int vty_init(const struct file_operation
static inline bool vt_force_oops_output(struct vc_data *vc)
{
- if (oops_in_progress && vc->vc_panic_force_write)
+ if (oops_in_progress && vc->vc_panic_force_write && panic_timeout >= 0)
return true;
return false;
}
_
Patches currently in -mm which might be from msb@xxxxxxxxxxxx are
linux-next.patch
panic-panic=-1-for-immediate-reboot.patch
panic-vt-do-not-force-oops-output-when-panic_timeout-0.patch
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