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nmi_backtrace: allow excluding an arbitrary CPU

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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 <dianders@chromium.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Lecopzer Chen <lecopzer.chen@mediatek.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Pingfan Liu <kernelfans@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Douglas Anderson
2023-08-04 07:00:42 -07:00
committed by Andrew Morton
parent 3c9d017cc2
commit 8d539b84f1
16 changed files with 32 additions and 32 deletions
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4
arch/arm/kernel/smp.c
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@@ -846,7 +846,7 @@ static void raise_nmi(cpumask_t *mask)
__ipi_send_mask(ipi_desc[IPI_CPU_BACKTRACE], mask);
}
void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)
{
nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_nmi);
nmi_trigger_cpumask_backtrace(mask, exclude_cpu, raise_nmi);
}