Re: [PATCH v9 5/9] perf config: Serialize config file access with a mutex

[sashiko-bot@kernel.org]

> From: Arnaldo Carvalho de Melo <acme@redhat.com>
> 
> Config file access shares the static parser state and, since
> perf_config__set_variable() became an entry point for background
> features, can run on more than one thread: a feature writing the
> config while perf top's display thread reads it.  Serialize parsing
> and rewriting with config_mutex and the whole read-modify-write of
> perf_config__set_variable() with config_update_mutex; config_set_mutex
> comes before it, as building the set parses the config files.
> 
> perf has its own mutex type, util/mutex.h; the file scope mutexes
> here use the DEFINE_MUTEX() static initializer added in the previous
> patch.  The two lazy inits that system_path() and home_perfconfig()
> do would leak all but one of the strings racing on two threads, so
> they move to DO_ONCE(), added in the previous patch as well.
> bad_config() runs on the dispatching thread, outside config_mutex, so
> it stops reading config_file_name, which the parsing thread owns.
> 
> Assisted-by: LLM
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20261004060457.3353-1-acme@kernel.org?part=5