linux-stable.git/arch/powerpc/kernel/watchdog.c, branch linux-rolling-stable

powerpc/watchdog: add support for hardlockup_sys_info sysctl

2026-01-15T06:16:22+00:00

Commit a9af76a78760 ("watchdog: add sys_info sysctls to dump sys info on
system lockup") adds 'hardlock_sys_info' systcl knob for general kernel
watchdog to control what kinds of system debug info to be dumped on
hardlockup.

Add similar support in powerpc watchdog code to make the sysctl knob more
general, which also fixes a compiling warning in general watchdog code
reported by 0day bot.

Link: https://lkml.kernel.org/r/20251231080309.39642-1-feng.tang@linux.alibaba.com
Fixes: a9af76a78760 ("watchdog: add sys_info sysctls to dump sys info on system lockup")
Signed-off-by: Feng Tang 
Reported-by: kernel test robot 
Closes: https://lore.kernel.org/oe-kbuild-all/202512030920.NFKtekA7-lkp@intel.com/
Suggested-by: Petr Mladek 
Reviewed-by: Petr Mladek 
Cc: Madhavan Srinivasan 
Cc: Michael Ellerman 
Cc: Nicholas Piggin 
Signed-off-by: Andrew Morton

powerpc/watchdog: Switch to use hrtimer_setup()

2025-02-18T09:32:31+00:00

hrtimer_setup() takes the callback function pointer as argument and
initializes the timer completely.

Replace hrtimer_init() and the open coded initialization of
hrtimer::function with the new setup mechanism.

Patch was created by using Coccinelle.

Signed-off-by: Nam Cao 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/all/099ebf6d352094a56e22fdfe76582b50f8fd6029.1738746821.git.namcao@linutronix.de

nmi_backtrace: allow excluding an arbitrary CPU

2023-08-18T17:19:00+00:00

The APIs that allow backtracing across CPUs have always had a way to
exclude the current CPU.  This convenience means callers didn't need to
find a place to allocate a CPU mask just to handle the common case.

Let's extend the API to take a CPU ID to exclude instead of just a
boolean.  This isn't any more complex for the API to handle and allows the
hardlockup detector to exclude a different CPU (the one it already did a
trace for) without needing to find space for a CPU mask.

Arguably, this new API also encourages safer behavior.  Specifically if
the caller wants to avoid tracing the current CPU (maybe because they
already traced the current CPU) this makes it more obvious to the caller
that they need to make sure that the current CPU ID can't change.

[akpm@linux-foundation.org: fix trigger_allbutcpu_cpu_backtrace() stub]
Link: https://lkml.kernel.org/r/20230804065935.v4.1.Ia35521b91fc781368945161d7b28538f9996c182@changeid
Signed-off-by: Douglas Anderson 
Acked-by: Michal Hocko 
Cc: kernel test robot 
Cc: Lecopzer Chen 
Cc: Petr Mladek 
Cc: Pingfan Liu 
Signed-off-by: Andrew Morton

watchdog/hardlockup: rename some "NMI watchdog" constants/function

2023-06-10T00:44:20+00:00

Do a search and replace of:
- NMI_WATCHDOG_ENABLED => WATCHDOG_HARDLOCKUP_ENABLED
- SOFT_WATCHDOG_ENABLED => WATCHDOG_SOFTOCKUP_ENABLED
- watchdog_nmi_ => watchdog_hardlockup_
- nmi_watchdog_available => watchdog_hardlockup_available
- nmi_watchdog_user_enabled => watchdog_hardlockup_user_enabled
- soft_watchdog_user_enabled => watchdog_softlockup_user_enabled
- NMI_WATCHDOG_DEFAULT => WATCHDOG_HARDLOCKUP_DEFAULT

Then update a few comments near where names were changed.

This is specifically to make it less confusing when we want to introduce
the buddy hardlockup detector, which isn't using NMIs.  As part of this,
we sanitized a few names for consistency.

[trix@redhat.com: make variables static]
  Link: https://lkml.kernel.org/r/20230525162822.1.I0fb41d138d158c9230573eaa37dc56afa2fb14ee@changeid
Link: https://lkml.kernel.org/r/20230519101840.v5.12.I91f7277bab4bf8c0cb238732ed92e7ce7bbd71a6@changeid
Signed-off-by: Douglas Anderson 
Signed-off-by: Tom Rix 
Reviewed-by: Tom Rix 
Cc: Andi Kleen 
Cc: Catalin Marinas 
Cc: Chen-Yu Tsai 
Cc: Christophe Leroy 
Cc: Colin Cross 
Cc: Daniel Thompson 
Cc: "David S. Miller" 
Cc: Guenter Roeck 
Cc: Ian Rogers 
Cc: Lecopzer Chen 
Cc: Marc Zyngier 
Cc: Mark Rutland 
Cc: Masayoshi Mizuma 
Cc: Matthias Kaehlcke 
Cc: Michael Ellerman 
Cc: Nicholas Piggin 
Cc: Petr Mladek 
Cc: Pingfan Liu 
Cc: Randy Dunlap 
Cc: "Ravi V. Shankar" 
Cc: Ricardo Neri 
Cc: Stephane Eranian 
Cc: Stephen Boyd 
Cc: Sumit Garg 
Cc: Tzung-Bi Shih 
Cc: Will Deacon 
Signed-off-by: Andrew Morton

powerpc/watchdog: introduce a NMI watchdog's factor

2022-07-27T11:36:02+00:00

Introduce a factor which would apply to the NMI watchdog timeout.

This factor is a percentage added to the watchdog_tresh value. The value is
set under the watchdog_mutex protection and lockup_detector_reconfigure()
is called to recompute wd_panic_timeout_tb.

Once the factor is set, it remains until it is set back to 0, which means
no impact.

Signed-off-by: Laurent Dufour 
Reviewed-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20220713154729.80789-4-ldufour@linux.ibm.com

powerpc: Fix all occurences of duplicate words

2022-07-25T02:05:15+00:00

Since commit 87c78b612f4f ("powerpc: Fix all occurences of "the the"")
fixed "the the", there's now a steady stream of patches fixing other
duplicate words.

Just fix them all at once, to save the overhead of dealing with
individual patches for each case.

This leaves a few cases of "that that", which in some contexts is
correct.

Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20220718095158.326606-1-mpe@ellerman.id.au

powerpc: fix typos in comments

2022-05-05T12:12:44+00:00

Various spelling mistakes in comments.
Detected with the help of Coccinelle.

Signed-off-by: Julia Lawall 
Reviewed-by: Joel Stanley 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20220430185654.5855-1-Julia.Lawall@inria.fr

powerpc/watchdog: help remote CPUs to flush NMI printk output

2021-11-29T12:08:43+00:00

The printk layer at the moment does not seem to have a good way to force
flush printk messages that are created in NMI context, except in the
panic path.

NMI-context printk messages normally get to the console with irq_work,
but that won't help if the CPU is stuck with irqs disabled, as can be
the case for hard lockup watchdog messages.

The watchdog currently flushes the printk buffers after detecting a
lockup on remote CPUs, but they may not have processed their NMI IPI
yet by that stage, or they may have self-detected a lockup in which
case they won't go via this NMI IPI path.

Improve the situation by having NMI-context mark a flag if it called
printk, and have watchdog timer interrupts check if that flag was set
and try to flush if it was. Latency is not a big problem because we
were already stuck for a while, just need to try to make sure the
messages eventually make it out.

Depends-on: 5d5e4522a7f4 ("printk: restore flushing of NMI buffers on remote CPUs after NMI backtraces")
Signed-off-by: Nicholas Piggin 
Reviewed-by: Laurent Dufour 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20211119113146.752759-6-npiggin@gmail.com

powerpc/watchdog: Fix wd_smp_last_reset_tb reporting

2021-11-25T10:48:39+00:00

wd_smp_last_reset_tb now gets reset by watchdog_smp_panic() as part of
marking CPUs stuck and removing them from the pending mask before it
begins any printing. This causes last reset times reported to be off.

Fix this by reading it into a local variable before it gets reset.

Fixes: 76521c4b0291 ("powerpc/watchdog: Avoid holding wd_smp_lock over printk and smp_send_nmi_ipi")
Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20211125103346.1188958-1-npiggin@gmail.com

powerpc/watchdog: read TB close to where it is used

2021-11-25T00:25:34+00:00

When taking watchdog actions, printing messages, comparing and
re-setting wd_smp_last_reset_tb, etc., read TB close to the point of use
and under wd_smp_lock or printing lock (if applicable).

This should keep timebase mostly monotonic with kernel log messages, and
could prevent (in theory) a laggy CPU updating wd_smp_last_reset_tb to
something a long way in the past, and causing other CPUs to appear to be
stuck.

These additional TB reads are all slowpath (lockup has been detected),
so performance does not matter.

Signed-off-by: Nicholas Piggin 
Reviewed-by: Laurent Dufour 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/20211110025056.2084347-5-npiggin@gmail.com