[PATCH v2 2/6] perf pmu: Remove logic for PMU name being NULL

From: Ian Rogers
Date: Thu Aug 24 2023 - 22:41:23 EST

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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@xxxxxxxxxx>
---
tools/perf/arch/arm64/util/mem-events.c | 2 +-
tools/perf/arch/powerpc/util/mem-events.c | 6 +++---
tools/perf/arch/x86/util/mem-events.c | 8 ++++----
tools/perf/arch/x86/util/pmu.c | 10 +++++-----
tools/perf/builtin-list.c | 2 +-
tools/perf/tests/pmu-events.c | 16 ++++++++--------
tools/perf/util/env.c | 8 ++------
tools/perf/util/header.c | 8 +-------
tools/perf/util/mem-events.c | 16 ++++++++--------
tools/perf/util/mem-events.h | 2 +-
tools/perf/util/parse-events.c | 7 ++-----
tools/perf/util/parse-events.h | 2 +-
tools/perf/util/parse-events.y | 2 +-
tools/perf/util/pmu.c | 16 +++++++++-------
tools/perf/util/pmu.h | 8 ++++----
15 files changed, 51 insertions(+), 62 deletions(-)

diff --git a/tools/perf/arch/arm64/util/mem-events.c b/tools/perf/arch/arm64/util/mem-events.c
index df817d1f9f3e..3bcc5c7035c2 100644
--- a/tools/perf/arch/arm64/util/mem-events.c
+++ b/tools/perf/arch/arm64/util/mem-events.c
@@ -20,7 +20,7 @@ struct perf_mem_event *perf_mem_events__ptr(int i)
return &perf_mem_events[i];
}

-char *perf_mem_events__name(int i, char *pmu_name __maybe_unused)
+const char *perf_mem_events__name(int i, const char *pmu_name __maybe_unused)
{
struct perf_mem_event *e = perf_mem_events__ptr(i);

diff --git a/tools/perf/arch/powerpc/util/mem-events.c b/tools/perf/arch/powerpc/util/mem-events.c
index 4120fafe0be4..78b986e5268d 100644
--- a/tools/perf/arch/powerpc/util/mem-events.c
+++ b/tools/perf/arch/powerpc/util/mem-events.c
@@ -3,10 +3,10 @@
#include "mem-events.h"

/* PowerPC does not support 'ldlat' parameter. */
-char *perf_mem_events__name(int i, char *pmu_name __maybe_unused)
+const char *perf_mem_events__name(int i, const char *pmu_name __maybe_unused)
{
if (i == PERF_MEM_EVENTS__LOAD)
- return (char *) "cpu/mem-loads/";
+ return "cpu/mem-loads/";

- return (char *) "cpu/mem-stores/";
+ return "cpu/mem-stores/";
}
diff --git a/tools/perf/arch/x86/util/mem-events.c b/tools/perf/arch/x86/util/mem-events.c
index a8a782bcb121..191b372f9a2d 100644
--- a/tools/perf/arch/x86/util/mem-events.c
+++ b/tools/perf/arch/x86/util/mem-events.c
@@ -52,7 +52,7 @@ bool is_mem_loads_aux_event(struct evsel *leader)
return leader->core.attr.config == MEM_LOADS_AUX;
}

-char *perf_mem_events__name(int i, char *pmu_name)
+const char *perf_mem_events__name(int i, const char *pmu_name)
{
struct perf_mem_event *e = perf_mem_events__ptr(i);

@@ -65,7 +65,7 @@ char *perf_mem_events__name(int i, char *pmu_name)

if (!pmu_name) {
mem_loads_name__init = true;
- pmu_name = (char *)"cpu";
+ pmu_name = "cpu";
}

if (perf_pmus__have_event(pmu_name, "mem-loads-aux")) {
@@ -82,12 +82,12 @@ char *perf_mem_events__name(int i, char *pmu_name)

if (i == PERF_MEM_EVENTS__STORE) {
if (!pmu_name)
- pmu_name = (char *)"cpu";
+ pmu_name = "cpu";

scnprintf(mem_stores_name, sizeof(mem_stores_name),
e->name, pmu_name);
return mem_stores_name;
}

- return (char *)e->name;
+ return e->name;
}
diff --git a/tools/perf/arch/x86/util/pmu.c b/tools/perf/arch/x86/util/pmu.c
index 65d8cdff4d5f..f428cffb0378 100644
--- a/tools/perf/arch/x86/util/pmu.c
+++ b/tools/perf/arch/x86/util/pmu.c
@@ -126,7 +126,7 @@ static int setup_pmu_alias_list(void)
return ret;
}

-static char *__pmu_find_real_name(const char *name)
+static const char *__pmu_find_real_name(const char *name)
{
struct pmu_alias *pmu_alias;

@@ -135,10 +135,10 @@ static char *__pmu_find_real_name(const char *name)
return pmu_alias->name;
}

- return (char *)name;
+ return name;
}

-char *pmu_find_real_name(const char *name)
+const char *pmu_find_real_name(const char *name)
{
if (cached_list)
return __pmu_find_real_name(name);
@@ -149,7 +149,7 @@ char *pmu_find_real_name(const char *name)
return __pmu_find_real_name(name);
}

-static char *__pmu_find_alias_name(const char *name)
+static const char *__pmu_find_alias_name(const char *name)
{
struct pmu_alias *pmu_alias;

@@ -160,7 +160,7 @@ static char *__pmu_find_alias_name(const char *name)
return NULL;
}

-char *pmu_find_alias_name(const char *name)
+const char *pmu_find_alias_name(const char *name)
{
if (cached_list)
return __pmu_find_alias_name(name);
diff --git a/tools/perf/builtin-list.c b/tools/perf/builtin-list.c
index 7fec2cca759f..e74d0223deb7 100644
--- a/tools/perf/builtin-list.c
+++ b/tools/perf/builtin-list.c
@@ -502,7 +502,7 @@ int cmd_list(int argc, const char **argv)
ret = -1;
goto out;
}
- default_ps.pmu_glob = pmu->name;
+ default_ps.pmu_glob = strdup(pmu->name);
}
}
print_cb.print_start(ps);
diff --git a/tools/perf/tests/pmu-events.c b/tools/perf/tests/pmu-events.c
index 3dc1ebee4d9f..94937378647a 100644
--- a/tools/perf/tests/pmu-events.c
+++ b/tools/perf/tests/pmu-events.c
@@ -522,7 +522,7 @@ static int test_core_pmu_event_aliases_cb(void *state, struct pmu_event_info *al
}

/* Verify aliases are as expected */
-static int __test_core_pmu_event_aliases(char *pmu_name, int *count)
+static int __test_core_pmu_event_aliases(const char *pmu_name, int *count)
{
struct perf_pmu_test_event const **test_event_table;
struct perf_pmu *pmu;
@@ -635,7 +635,7 @@ static int __test_uncore_pmu_event_aliases(struct perf_pmu_test_pmu *test_pmu)
static struct perf_pmu_test_pmu test_pmus[] = {
{
.pmu = {
- .name = (char *)"hisi_sccl1_ddrc2",
+ .name = "hisi_sccl1_ddrc2",
.is_uncore = 1,
},
.aliases = {
@@ -644,7 +644,7 @@ static struct perf_pmu_test_pmu test_pmus[] = {
},
{
.pmu = {
- .name = (char *)"uncore_cbox_0",
+ .name = "uncore_cbox_0",
.is_uncore = 1,
},
.aliases = {
@@ -655,7 +655,7 @@ static struct perf_pmu_test_pmu test_pmus[] = {
},
{
.pmu = {
- .name = (char *)"hisi_sccl3_l3c7",
+ .name = "hisi_sccl3_l3c7",
.is_uncore = 1,
},
.aliases = {
@@ -664,7 +664,7 @@ static struct perf_pmu_test_pmu test_pmus[] = {
},
{
.pmu = {
- .name = (char *)"uncore_imc_free_running_0",
+ .name = "uncore_imc_free_running_0",
.is_uncore = 1,
},
.aliases = {
@@ -673,7 +673,7 @@ static struct perf_pmu_test_pmu test_pmus[] = {
},
{
.pmu = {
- .name = (char *)"uncore_imc_0",
+ .name = "uncore_imc_0",
.is_uncore = 1,
},
.aliases = {
@@ -682,7 +682,7 @@ static struct perf_pmu_test_pmu test_pmus[] = {
},
{
.pmu = {
- .name = (char *)"uncore_sys_ddr_pmu0",
+ .name = "uncore_sys_ddr_pmu0",
.is_uncore = 1,
.id = (char *)"v8",
},
@@ -692,7 +692,7 @@ static struct perf_pmu_test_pmu test_pmus[] = {
},
{
.pmu = {
- .name = (char *)"uncore_sys_ccn_pmu4",
+ .name = "uncore_sys_ccn_pmu4",
.is_uncore = 1,
.id = (char *)"0x01",
},
diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c
index 9eabf3ec56e9..a164164001fb 100644
--- a/tools/perf/util/env.c
+++ b/tools/perf/util/env.c
@@ -324,11 +324,9 @@ int perf_env__read_pmu_mappings(struct perf_env *env)
u32 pmu_num = 0;
struct strbuf sb;

- while ((pmu = perf_pmus__scan(pmu))) {
- if (!pmu->name)
- continue;
+ while ((pmu = perf_pmus__scan(pmu)))
pmu_num++;
- }
+
if (!pmu_num) {
pr_debug("pmu mappings not available\n");
return -ENOENT;
@@ -339,8 +337,6 @@ int perf_env__read_pmu_mappings(struct perf_env *env)
return -ENOMEM;

while ((pmu = perf_pmus__scan(pmu))) {
- if (!pmu->name)
- continue;
if (strbuf_addf(&sb, "%u:%s", pmu->type, pmu->name) < 0)
goto error;
/* include a NULL character at the end */
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 13c71d28e0eb..9f35d86a3351 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -746,20 +746,14 @@ static int write_pmu_mappings(struct feat_fd *ff,
* Do a first pass to count number of pmu to avoid lseek so this
* works in pipe mode as well.
*/
- while ((pmu = perf_pmus__scan(pmu))) {
- if (!pmu->name)
- continue;
+ while ((pmu = perf_pmus__scan(pmu)))
pmu_num++;
- }

ret = do_write(ff, &pmu_num, sizeof(pmu_num));
if (ret < 0)
return ret;

while ((pmu = perf_pmus__scan(pmu))) {
- if (!pmu->name)
- continue;
-
ret = do_write(ff, &pmu->type, sizeof(pmu->type));
if (ret < 0)
return ret;
diff --git a/tools/perf/util/mem-events.c b/tools/perf/util/mem-events.c
index c07fe3a90722..39ffe8ceb380 100644
--- a/tools/perf/util/mem-events.c
+++ b/tools/perf/util/mem-events.c
@@ -37,7 +37,7 @@ struct perf_mem_event * __weak perf_mem_events__ptr(int i)
return &perf_mem_events[i];
}

-char * __weak perf_mem_events__name(int i, char *pmu_name __maybe_unused)
+const char * __weak perf_mem_events__name(int i, const char *pmu_name __maybe_unused)
{
struct perf_mem_event *e = perf_mem_events__ptr(i);

@@ -53,7 +53,7 @@ char * __weak perf_mem_events__name(int i, char *pmu_name __maybe_unused)
return mem_loads_name;
}

- return (char *)e->name;
+ return e->name;
}

__weak bool is_mem_loads_aux_event(struct evsel *leader __maybe_unused)
@@ -186,7 +186,6 @@ int perf_mem_events__record_args(const char **rec_argv, int *argv_nr,
int i = *argv_nr, k = 0;
struct perf_mem_event *e;
struct perf_pmu *pmu;
- char *s;

for (int j = 0; j < PERF_MEM_EVENTS__MAX; j++) {
e = perf_mem_events__ptr(j);
@@ -209,15 +208,16 @@ int perf_mem_events__record_args(const char **rec_argv, int *argv_nr,
}

while ((pmu = perf_pmus__scan(pmu)) != NULL) {
+ const char *s = perf_mem_events__name(j, pmu->name);
+
rec_argv[i++] = "-e";
- s = perf_mem_events__name(j, pmu->name);
if (s) {
- s = strdup(s);
- if (!s)
+ char *copy = strdup(s);
+ if (!copy)
return -1;

- rec_argv[i++] = s;
- rec_tmp[k++] = s;
+ rec_argv[i++] = copy;
+ rec_tmp[k++] = copy;
}
}
}
diff --git a/tools/perf/util/mem-events.h b/tools/perf/util/mem-events.h
index 12372309d60e..b40ad6ea93fc 100644
--- a/tools/perf/util/mem-events.h
+++ b/tools/perf/util/mem-events.h
@@ -38,7 +38,7 @@ extern unsigned int perf_mem_events__loads_ldlat;
int perf_mem_events__parse(const char *str);
int perf_mem_events__init(void);

-char *perf_mem_events__name(int i, char *pmu_name);
+const char *perf_mem_events__name(int i, const char *pmu_name);
struct perf_mem_event *perf_mem_events__ptr(int i);
bool is_mem_loads_aux_event(struct evsel *leader);

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index c71e135d7335..621bdd157a0f 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -262,7 +262,7 @@ __add_event(struct list_head *list, int *idx,
evsel->core.is_pmu_core = pmu ? pmu->is_core : false;
evsel->auto_merge_stats = auto_merge_stats;
evsel->pmu = pmu;
- evsel->pmu_name = pmu && pmu->name ? strdup(pmu->name) : NULL;
+ evsel->pmu_name = pmu ? strdup(pmu->name) : NULL;

if (name)
evsel->name = strdup(name);
@@ -437,9 +437,6 @@ bool parse_events__filter_pmu(const struct parse_events_state *parse_state,
if (parse_state->pmu_filter == NULL)
return false;

- if (pmu->name == NULL)
- return true;
-
return strcmp(parse_state->pmu_filter, pmu->name) != 0;
}

@@ -1292,7 +1289,7 @@ static bool config_term_percore(struct list_head *config_terms)
}

int parse_events_add_pmu(struct parse_events_state *parse_state,
- struct list_head *list, char *name,
+ struct list_head *list, const char *name,
struct list_head *head_config,
bool auto_merge_stats, void *loc_)
{
diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
index c7f779420723..c4e8d8e94b28 100644
--- a/tools/perf/util/parse-events.h
+++ b/tools/perf/util/parse-events.h
@@ -176,7 +176,7 @@ int parse_events_add_breakpoint(struct parse_events_state *parse_state,
u64 addr, char *type, u64 len,
struct list_head *head_config);
int parse_events_add_pmu(struct parse_events_state *parse_state,
- struct list_head *list, char *name,
+ struct list_head *list, const char *name,
struct list_head *head_config,
bool auto_merge_stats, void *loc);

diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
index 00da1f8c0baf..3a9d4e2513b5 100644
--- a/tools/perf/util/parse-events.y
+++ b/tools/perf/util/parse-events.y
@@ -307,7 +307,7 @@ PE_NAME opt_pmu_config
}

while ((pmu = perf_pmus__scan(pmu)) != NULL) {
- char *name = pmu->name;
+ const char *name = pmu->name;

if (parse_events__filter_pmu(parse_state, pmu))
continue;
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;
diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
index bae0de3ed7a5..e90169ab3dc2 100644
--- a/tools/perf/util/pmu.h
+++ b/tools/perf/util/pmu.h
@@ -39,7 +39,7 @@ struct perf_pmu_caps {
*/
struct perf_pmu {
/** @name: The name of the PMU such as "cpu". */
- char *name;
+ const char *name;
/**
* @alias_name: Optional alternate name for the PMU determined in
* architecture specific code.
@@ -249,10 +249,10 @@ void perf_pmu__warn_invalid_config(struct perf_pmu *pmu, __u64 config,
const char *config_name);
void perf_pmu__warn_invalid_formats(struct perf_pmu *pmu);

-int perf_pmu__match(char *pattern, char *name, char *tok);
+int perf_pmu__match(const char *pattern, const char *name, const char *tok);

-char *pmu_find_real_name(const char *name);
-char *pmu_find_alias_name(const char *name);
+const char *pmu_find_real_name(const char *name);
+const char *pmu_find_alias_name(const char *name);
double perf_pmu__cpu_slots_per_cycle(void);
int perf_pmu__event_source_devices_scnprintf(char *pathname, size_t size);
int perf_pmu__pathname_scnprintf(char *buf, size_t size,
--
2.42.0.rc2.253.gd59a3bf2b4-goog

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