On 26/06/2024 10:00, Petr Mladek wrote:
On Tue 2024-06-25 14:39:29, Jocelyn Falempe wrote:
kmsg_dump doesn't forward the panic reason string to the kmsg_dumper
callback.
This patch adds a new parameter "const char *desc" to the kmsg_dumper
dump() callback, and update all drivers that are using it.
To avoid updating all kmsg_dump() call, it adds a kmsg_dump_desc()
function and a macro for backward compatibility.
I've written this for drm_panic, but it can be useful for other
kmsg_dumper.
It allows to see the panic reason, like "sysrq triggered crash"
or "VFS: Unable to mount root fs on xxxx" on the drm panic screen.
Signed-off-by: Jocelyn Falempe <jfalempe@xxxxxxxxxx>
---
arch/powerpc/kernel/nvram_64.c | 3 ++-
arch/powerpc/platforms/powernv/opal-kmsg.c | 3 ++-
drivers/gpu/drm/drm_panic.c | 3 ++-
drivers/hv/hv_common.c | 3 ++-
drivers/mtd/mtdoops.c | 3 ++-
fs/pstore/platform.c | 3 ++-
include/linux/kmsg_dump.h | 13 ++++++++++---
kernel/panic.c | 2 +-
kernel/printk/printk.c | 8 +++++---
9 files changed, 28 insertions(+), 13 deletions(-)
The parameter is added into all dumpers. I guess that it would be
used only drm_panic() because it is graphics and might be "fancy".
The others simply dump the log buffer and the reason is in
the dumped log as well.
Ok, I also tried to retrieve the reason from the dumped log, but that's
really fragile.
Anyway, the passed buffer is static. Alternative solution would
be to make it global and export it like, for example, panic_cpu.
It's not a static buffer, because the string is generated at runtime.
eg: https://elixir.bootlin.com/linux/latest/source/arch/arm/mm/init.c#L158
So it will be hard to avoid race conditions.
Best Regards,
Petr
