Arnaldo Carvalho de Melo 4456c404c6 perf mutex: Add a robust, process-shared mutex initializer ... A mutex held by a process that can die before unlocking it, like the tests forked by 'perf test' that will take turns using the per user budget set in kernel.perf_event_mlock_kb, has to be taken over by the next locker instead of staying locked forever. Robust mutexes, on top of the kernel's robust futexes, do that: when an owner dies while holding it the kernel marks the futex word owner-died and the next pthread_mutex_lock() returns EOWNERDEAD, then mutex_lock() makes it consistent and takes it over; mutex_trylock() and cond_wait() come back with EOWNERDEAD too, so they take it over the same way, with mutex_trylock() giving the mutex back when it can't be taken over: it is held all the same, and a failed trylock must not leak it. Add mutex_init_pshared_robust(), returning false when robust mutexes aren't available: from libcs without the API, gated by a feature check, to musl and glibc refusing them at runtime, when get_robust_list(2) or set_robust_list(2) aren't usable. glibc only sets a flag in pthread_mutexattr_setrobust(), refusing the mutex itself in pthread_mutex_init() with ENOTSUP instead, other errors from it still being reported. Robust mutexes being unavailable isn't an error, just a debug message for whoever then falls back. Reviewed-by: Ian Rogers <irogers@google.com> Tested-by: Ian Rogers <irogers@google.com> Assisted-by: LLM Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>		2026-10-17 10:30:20 -03:00
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feature	perf mutex: Add a robust, process-shared mutex initializer	2026-10-17 10:30:20 -03:00
tests
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Build	tools build: Fix fixdep dependencies	2025-10-14 14:45:20 -07:00
Build.include	tools build: Fix rust cross compilation	2026-03-04 11:37:30 -03:00
fixdep.c
Makefile	perf build: Fix perf build issues with fixdep	2025-10-23 09:53:49 +02:00
Makefile.build	tools build: Make in-target rule robust against too long argument error	2026-03-04 11:21:48 -03:00
Makefile.feature	perf mutex: Add a robust, process-shared mutex initializer	2026-10-17 10:30:20 -03:00
Makefile.include