Commit e77b0236 authored by Ian Rogers's avatar Ian Rogers Committed by Arnaldo Carvalho de Melo
Browse files

perf maps: Add maps__load_first() 



Avoid bpf_lock_contention_read touching the internal maps data structure
by adding a helper function. As access is done directly on the map in
maps, hold the read lock to stop it being removed.

Signed-off-by: default avatarIan Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Changbin Du <changbin.du@huawei.com>
Cc: Colin Ian King <colin.i.king@gmail.com>
Cc: Dmitrii Dolgov <9erthalion6@gmail.com>
Cc: German Gomez <german.gomez@arm.com>
Cc: Guilherme Amadio <amadio@gentoo.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Li Dong <lidong@vivo.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Ming Wang <wangming01@loongson.cn>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nick Terrell <terrelln@fb.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Steinar H. Gunderson <sesse@google.com>
Cc: Vincent Whitchurch <vincent.whitchurch@axis.com>
Cc: Wenyu Liu <liuwenyu7@huawei.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Link: https://lore.kernel.org/r/20231207011722.1220634-20-irogers@google.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 90849527

tools/perf/util/bpf_lock_contention.c

+1 −1
Original line number Diff line number Diff line
@@ -318,7 +318,7 @@ int lock_contention_read(struct lock_contention *con) 
	}



	/* make sure it loads the kernel map */

	map__load(maps__first(machine->kmaps)->map);

	maps__load_first(machine->kmaps);



	prev_key = NULL;

	while (!bpf_map_get_next_key(fd, prev_key, &key)) {

tools/perf/util/maps.c

+13 −0
Original line number Diff line number Diff line
@@ -793,3 +793,16 @@ int maps__merge_in(struct maps *kmaps, struct map *new_map) 
	}

	return err;

}



void maps__load_first(struct maps *maps)

{

	struct map_rb_node *first;



	down_read(maps__lock(maps));



	first = maps__first(maps);

	if (first)

		map__load(first->map);



	up_read(maps__lock(maps));

}

tools/perf/util/maps.h

+2 −0
Original line number Diff line number Diff line
@@ -142,4 +142,6 @@ void __maps__sort_by_name(struct maps *maps); 


void maps__fixup_end(struct maps *maps);



void maps__load_first(struct maps *maps);



#endif // __PERF_MAPS_H