linux-stable.git/include/linux/printk.h, branch v7.0.10

lib/hexdump: print_hex_dump_bytes() calls print_hex_dump_debug()

2026-05-23T11:09:15+00:00

[ Upstream commit 36776b7f8a8955b4e75b5d490a75fee0c7a2a7ef ]

print_hex_dump_bytes() claims to be a simple wrapper around
print_hex_dump(), but it actally calls print_hex_dump_debug(), which
means no output is printed if (dynamic) DEBUG is disabled.

Update the documentation to match the implementation.

Fixes: 091cb0994edd20d6 ("lib/hexdump: make print_hex_dump_bytes() a nop on !DEBUG builds")
Signed-off-by: Geert Uytterhoeven 
Reviewed-by: Petr Mladek 
Link: https://patch.msgid.link/3d5c3069fd9102ecaf81d044b750cd613eb72a08.1774970392.git.geert+renesas@glider.be
Signed-off-by: Petr Mladek 
Signed-off-by: Sasha Levin

printk: add print_hex_dump_devel()

2026-05-14T13:31:20+00:00

[ Upstream commit d134feeb5df33fbf77f482f52a366a44642dba09 ]

Add print_hex_dump_devel() as the hex dump equivalent of pr_devel(),
which emits output only when DEBUG is enabled, but keeps call sites
compiled otherwise.

Suggested-by: Herbert Xu 
Signed-off-by: Thorsten Blum 
Reviewed-by: John Ogness 
Signed-off-by: Herbert Xu 
Stable-dep-of: 177730a273b1 ("crypto: caam - guard HMAC key hex dumps in hash_digest_key")
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

sysctl: Remove unused ctl_table forward declarations

2026-01-05T12:54:41+00:00

Remove superfluous forward declarations of ctl_table from header files
where they are no longer needed. These declarations were left behind
after sysctl code refactoring and cleanup.

Reviewed-by: Jan Kara 
Acked-by: Muchun Song 
Reviewed-by: Petr Mladek 
Acked-by: Paolo Abeni 
Signed-off-by: Joel Granados

panic/printk: replace this_cpu_in_panic() with panic_on_this_cpu()

2025-09-14T00:32:52+00:00

The helper this_cpu_in_panic() duplicated logic already provided by
panic_on_this_cpu().

Remove this_cpu_in_panic() and switch all users to panic_on_this_cpu().

This simplifies the code and avoids having two helpers for the same check.

Link: https://lkml.kernel.org/r/20250825022947.1596226-8-wangjinchao600@gmail.com
Signed-off-by: Jinchao Wang 
Cc: Anna Schumaker 
Cc: Baoquan He 
Cc: "Darrick J. Wong" 
Cc: Dave Young 
Cc: Doug Anderson 
Cc: "Guilherme G. Piccoli" 
Cc: Helge Deller 
Cc: Ingo Molnar 
Cc: Jason Gunthorpe 
Cc: Joanthan Cameron 
Cc: Joel Granados 
Cc: John Ogness 
Cc: Kees Cook 
Cc: Li Huafei 
Cc: "Luck, Tony" 
Cc: Luo Gengkun 
Cc: Max Kellermann 
Cc: Nam Cao 
Cc: oushixiong 
Cc: Petr Mladek 
Cc: Qianqiang Liu 
Cc: Sergey Senozhatsky 
Cc: Sohil Mehta 
Cc: Steven Rostedt 
Cc: Tejun Heo 
Cc: Thomas Gleinxer 
Cc: Thomas Zimemrmann 
Cc: Thorsten Blum 
Cc: Ville Syrjala 
Cc: Vivek Goyal 
Cc: Yicong Yang 
Cc: Yunhui Cui 
Cc: Yury Norov (NVIDIA) 
Signed-off-by: Andrew Morton

printk: Make vprintk_deferred() public

2025-07-09T19:27:00+00:00

vprintk_deferred() is useful for implementing runtime verification
reactors. Make it public.

Signed-off-by: Nam Cao 
Reviewed-by: Petr Mladek 
Signed-off-by: Steven Rostedt (Google)

Flush console log from kernel_power_off()

2025-03-05T02:44:29+00:00

Kernels built with CONFIG_PREEMPT_RT=y can lose significant console output
and shutdown time, which hides shutdown-time RCU issues from rcutorture.
Therefore, make pr_flush() public and invoke it after then last print
in kernel_power_off().

[ paulmck: Apply John Ogness feedback. ]
[ paulmck: Appy Sebastian Andrzej Siewior feedback. ]
[ paulmck: Apply kernel test robot feedback. ]

Signed-off-by: Paul E. McKenney 
Reviewed-by: John Ogness 
Reviewed-by: Petr Mladek 
Cc: Steven Rostedt 
Cc: Sergey Senozhatsky 
Link: https://lore.kernel.org/r/5f743488-dc2a-4f19-bdda-cf50b9314832@paulmck-laptop
Signed-off-by: Boqun Feng

printk: add dummy printk_force_console_enter/exit helpers

2024-11-13T10:00:23+00:00

The newly added interface is broken when PRINTK is disabled:

drivers/tty/sysrq.c: In function '__handle_sysrq':
drivers/tty/sysrq.c:601:9: error: implicit declaration of function 'printk_force_console_enter' [-Wimplicit-function-declaration]
  601 |         printk_force_console_enter();
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/tty/sysrq.c:611:25: error: implicit declaration of function 'printk_force_console_exit' [-Wimplicit-function-declaration]
  611 |                         printk_force_console_exit();
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~

Add empty stub functions for both.

Fixes: ed76c07c6885 ("printk: Introduce FORCE_CON flag")
Signed-off-by: Arnd Bergmann 
Reviewed-by: Andy Shevchenko 
Reviewed-by: Marcos Paulo de Souza 
Tested-by: Marcos Paulo de Souza 
Link: https://lore.kernel.org/r/20241112142939.724093-1-arnd@kernel.org
Signed-off-by: Petr Mladek

printk: Introduce FORCE_CON flag

2024-11-11T11:53:31+00:00

Introduce FORCE_CON flag to printk. The new flag will make it possible to
create a context where printk messages will never be suppressed.

This mechanism will be used in the next patch to create a force_con
context on sysrq handling, removing an existing workaround on the
loglevel global variable. The workaround existed to make sure that sysrq
header messages were sent to all consoles, but this doesn't work with
deferred messages because the loglevel might be restored to its original
value before a console flushes the messages.

Signed-off-by: Marcos Paulo de Souza 
Reviewed-by: John Ogness 
Reviewed-by: Petr Mladek 
Acked-by: Greg Kroah-Hartman 
Link: https://lore.kernel.org/r/20241105-printk-loud-con-v2-1-bd3ecdf7b0e4@suse.com
Signed-off-by: Petr Mladek

printk: Coordinate direct printing in panic

2024-08-21T12:56:25+00:00

If legacy and nbcon consoles are registered and the nbcon
consoles are allowed to flush (i.e. no boot consoles
registered), the legacy consoles will no longer perform
direct printing on the panic CPU until after the backtrace
has been stored. This will give the safe nbcon consoles a
chance to print the panic messages before allowing the
unsafe legacy consoles to print.

If no nbcon consoles are registered or they are not allowed
to flush because boot consoles are registered, there is no
change in behavior (i.e. legacy consoles will always attempt
to print from the printk() caller context).

Signed-off-by: John Ogness 
Reviewed-by: Petr Mladek 
Link: https://lore.kernel.org/r/20240820063001.36405-30-john.ogness@linutronix.de
Signed-off-by: Petr Mladek

printk: nbcon: Add unsafe flushing on panic

2024-08-21T12:56:24+00:00

Add nbcon_atomic_flush_unsafe() to flush all nbcon consoles
using the write_atomic() callback and allowing unsafe hostile
takeovers. Call this at the end of panic() as a final attempt
to flush any pending messages.

Note that legacy consoles use unsafe methods for flushing
from the beginning of panic (see bust_spinlocks()). Therefore,
systems using both legacy and nbcon consoles may still fail to
see panic messages due to unsafe legacy console usage.

Signed-off-by: John Ogness 
Reviewed-by: Petr Mladek 
Link: https://lore.kernel.org/r/20240820063001.36405-27-john.ogness@linutronix.de
Signed-off-by: Petr Mladek