Re: [PATCH v7 07/11] perf bpf-filter: Support per-process and semi-global locks in lock_held()

[sashiko-bot@kernel.org]

> Extend the lock_held() BPF sample filter to support well-known
> per-process and semi-global kernel locks:
> - mmap_lock (or mmap_sem): current->mm->mmap_lock, supporting both
>   read/shared (lock_held_read(mmap_lock) / lock_held(mmap_lock:R)) and
>   write/exclusive (lock_held_write(mmap_lock) / lock_held(mmap_lock:W))
>   modes. Write ownership is inspected directly via is_rwsem_writer_owner()
>   without attaching fentry/fexit hooks.
> - siglock: current->sighand->siglock.
> - rq_lock: per-CPU scheduler runqueue locks.
> - zone_lock: memory management NUMA zone locks.
> 
> For rq_lock and zone_lock, reuse do_collect_lock_syms() from lock_data.h
> via a raw_tp/bpf_test_finish program run at filter setup time to
> populate the lock_syms map with each CPU's rq_lock and each NUMA node's
> zone_lock addresses.
> 
> Only zone_lock needs NUMA zone data from kallsyms and sysfs, so fail filter
> setup if it can't be found rather than attaching a filter that can never
> match.
> 
> Example usage:
> 
>   # perf record -a -g -e cycles --filter 'lock_held(mmap_lock)' \
>       -- perf bench mem mmap -t 2 -l 100
>   # perf record -a -g -e cycles --filter 'lock_held_read(mmap_lock)' ...
>   # perf record -a -g -e cycles --filter 'lock_held_write(mmap_lock)' ...
>   # perf record -a -g -e cycles --filter 'lock_held(mmap_lock:W)' ...
> 
> Signed-off-by: Ian Rogers <irogers@google.com>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261023190558.3050796-1-irogers@google.com?part=7