perf pmu: Remove logic for PMU name being NULL

The PMU name could be NULL in the case of the fake_pmu. Initialize the
name for the fake_pmu to "fake" so that all other logic can assume it
is initialized. Add a const to the type of name so that a literal can
be used to avoid additional initialization code. Propagate the cost
through related routines and remove now unnecessary "(char *)"
casts. Doing this located a bug in builtin-list for the pmu_glob that
was missing a strdup.

Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20230825024002.801955-3-irogers@google.com
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: James Clark <james.clark@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Wei Li <liwei391@huawei.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Ming Wang <wangming01@loongson.cn>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-perf-users@vger.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 9 insertions, 7 deletions

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index bb2ca29cd7bd..a96ccc5c3b51 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -29,7 +29,9 @@
 #include "fncache.h"
 #include "util/evsel_config.h"
 
-struct perf_pmu perf_pmu__fake;
+struct perf_pmu perf_pmu__fake = {
+	.name = "fake",
+};
 
 #define UNIT_MAX_LEN	31 /* max length for event unit name */
 
@@ -967,13 +969,13 @@ perf_pmu__get_default_config(struct perf_pmu *pmu __maybe_unused)
 	return NULL;
 }
 
-char * __weak
+const char * __weak
 pmu_find_real_name(const char *name)
 {
-	return (char *)name;
+	return name;
 }
 
-char * __weak
+const char * __weak
 pmu_find_alias_name(const char *name __maybe_unused)
 {
 	return NULL;
@@ -991,8 +993,8 @@ struct perf_pmu *perf_pmu__lookup(struct list_head *pmus, int dirfd, const char
 {
 	struct perf_pmu *pmu;
 	__u32 type;
-	char *name = pmu_find_real_name(lookup_name);
-	char *alias_name;
+	const char *name = pmu_find_real_name(lookup_name);
+	const char *alias_name;
 
 	pmu = zalloc(sizeof(*pmu));
 	if (!pmu)
@@ -1974,7 +1976,7 @@ void perf_pmu__warn_invalid_config(struct perf_pmu *pmu, __u64 config,
 		   name ?: "N/A", buf, config_name, config);
 }
 
-int perf_pmu__match(char *pattern, char *name, char *tok)
+int perf_pmu__match(const char *pattern, const char *name, const char *tok)
 {
 	if (!name)
 		return -1;