perf pmu: Remove perf_pmu__hybrid_mounted

perf_pmu__hybrid_mounted is used to detect whether cpu_core or
cpu_atom is mounted with a non-empty cpus file by
pmu_lookup. Discussion [1] showed the empty cpus file check to be
redundant and so pmu_lookup needn't have a call to
perf_pmu__hybrid_mounted.

Checking hybrid_mounted in pmu_is_uncore is redundant as the next
cpumask read will fail returning false.

Reduce the scope of perf_pmu__find_hybrid_pmu by making it static.

[1] https://lore.kernel.org/lkml/20230524221831.1741381-17-irogers@google.com/Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ali Saidi <alisaidi@amazon.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Dmitrii Dolgov <9erthalion6@gmail.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jing Zhang <renyu.zj@linux.alibaba.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kang Minchul <tegongkang@gmail.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Ming Wang <wangming01@loongson.cn>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Sandipan Das <sandipan.das@amd.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20230527072210.2900565-16-irogers@google.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/pmu-hybrid.c

@@ -18,20 +18,7 @@
 
 LIST_HEAD(perf_pmu__hybrid_pmus);
 
-bool perf_pmu__hybrid_mounted(const char *name)
-{
-	int cpu;
-	char pmu_name[PATH_MAX];
-	struct perf_pmu pmu = {.name = pmu_name};
-
-	if (strncmp(name, "cpu_", 4))
-		return false;
-
-	strlcpy(pmu_name, name, sizeof(pmu_name));
-	return perf_pmu__scan_file(&pmu, "cpus", "%u", &cpu) > 0;
-}
-
-struct perf_pmu *perf_pmu__find_hybrid_pmu(const char *name)
+static struct perf_pmu *perf_pmu__find_hybrid_pmu(const char *name)
 {
 	struct perf_pmu *pmu;
 

tools/perf/util/pmu-hybrid.h

@@ -13,9 +13,6 @@ extern struct list_head perf_pmu__hybrid_pmus;
 #define perf_pmu__for_each_hybrid_pmu(pmu)	\
 	list_for_each_entry(pmu, &perf_pmu__hybrid_pmus, hybrid_list)
 
-bool perf_pmu__hybrid_mounted(const char *name);
-
-struct perf_pmu *perf_pmu__find_hybrid_pmu(const char *name);
 bool perf_pmu__is_hybrid(const char *name);
 
 static inline int perf_pmu__hybrid_pmu_num(void)

tools/perf/util/pmu.c

@@ -617,9 +617,6 @@ static bool pmu_is_uncore(int dirfd, const char *name)
 {
 	int fd;
 
-	if (perf_pmu__hybrid_mounted(name))
-		return false;
-
 	fd = perf_pmu__pathname_fd(dirfd, name, "cpumask", O_PATH);
 	if (fd < 0)
 		return false;
@@ -907,15 +904,8 @@ static struct perf_pmu *pmu_lookup(int dirfd, const char *lookup_name)
 	LIST_HEAD(aliases);
 	__u32 type;
 	char *name = pmu_find_real_name(lookup_name);
-	bool is_hybrid = perf_pmu__hybrid_mounted(name);
 	char *alias_name;
 
-	/*
-	 * Check pmu name for hybrid and the pmu may be invalid in sysfs
-	 */
-	if (!strncmp(name, "cpu_", 4) && !is_hybrid)
-		return NULL;
-
 	/*
 	 * The pmu data we store & need consists of the pmu
 	 * type value and format definitions. Load both right
@@ -936,7 +926,6 @@ static struct perf_pmu *pmu_lookup(int dirfd, const char *lookup_name)
 
 	pmu->cpus = pmu_cpumask(dirfd, name);
 	pmu->name = strdup(name);
-
 	if (!pmu->name)
 		goto err;
 
@@ -967,7 +956,7 @@ static struct perf_pmu *pmu_lookup(int dirfd, const char *lookup_name)
 	list_splice(&aliases, &pmu->aliases);
 	list_add_tail(&pmu->list, &pmus);
 
-	if (is_hybrid)
+	if (!strcmp(name, "cpu_core") || !strcmp(name, "cpu_atom"))
 		list_add_tail(&pmu->hybrid_list, &perf_pmu__hybrid_pmus);
 	else
 		INIT_LIST_HEAD(&pmu->hybrid_list);