Re: [PATCH v3 15/18] perf mutex: Add thread safety annotations

Arnaldo Carvalho de Melo
2022-08-26T19:13:48Z

Em Fri, Aug 26, 2022 at 10:00:43AM -0700, Ian Rogers escreveu:
> On Fri, Aug 26, 2022 at 9:45 AM Arnaldo Carvalho de Melo
> <acme@kernel.org> wrote:
> >
> > Em Wed, Aug 24, 2022 at 08:38:58AM -0700, Ian Rogers escreveu:
> > > Add thread safety annotations to struct mutex so that when compiled with
> > > clang's -Wthread-safety warnings are generated for erroneous lock
> > > patterns. NO_THREAD_SAFETY_ANALYSIS is needed for
> > > mutex_lock/mutex_unlock as the analysis doesn't under pthread calls.
> >
> > So even having the guards checking if the attribute is available it
> > seems at least clang 11.0 is needed, as the "lockable" arg was
> > introduced there:
> >
> > 37 42.61 fedora:32 : FAIL clang version 10.0.1 (Fedora 10.0.1-3.fc32)
> > In file included from /git/perf-6.0.0-rc2/tools/perf/util/../ui/ui.h:5:
> > /git/perf-6.0.0-rc2/tools/perf/util/../ui/../util/mutex.h:74:8: error: invalid capability name 'lockable'; capability name must be 'mutex' or 'role' [-Werror,-Wthread-safety-attributes]
> > struct LOCKABLE mutex {
> > ^
> > /git/perf-6.0.0-rc2/tools/perf/util/../ui/../util/mutex.h:35:44: note: expanded from macro 'LOCKABLE'
> > #define LOCKABLE __attribute__((capability("lockable")))
>
>
> capability("lockable") can just be lockable, the capability
> generalization came in a later clang release.
>
> That is change:
> #define LOCKABLE __attribute__((capability("lockable")))
> to:
> #define LOCKABLE __attribute__((lockable))
>
> and later clangs take the earlier name. Do you want a v5 for this 1 liner?

I did it and I'm now testing, thanks.

- Arnaldo

diff --git a/tools/perf/util/mutex.h b/tools/perf/util/mutex.h
index 48a2d87598f0d725..29b5494b213a3fc9 100644
--- a/tools/perf/util/mutex.h
+++ b/tools/perf/util/mutex.h
@@ -32,7 +32,7 @@
#define PT_GUARDED_BY(x) __attribute__((pt_guarded_by(x)))

/* Documents if a type is a lockable type. */
-#define LOCKABLE __attribute__((capability("lockable")))
+#define LOCKABLE __attribute__((lockable))

/* Documents functions that acquire a lock in the body of a function, and do not release it. */
#define EXCLUSIVE_LOCK_FUNCTION(...) __attribute__((exclusive_lock_function(__VA_ARGS__)))

- Arnaldo