Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | Date | Fri, 23 Dec 2022 10:39:01 +0800 | From | Leo Yan <> | Subject | Re: [PATCH v2 1/7] perf: Remove duplication around EVENT_SOURCE_DEVICE_PATH |
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On Thu, Dec 22, 2022 at 04:03:21PM +0000, James Clark wrote: > The pattern for accessing EVENT_SOURCE_DEVICE_PATH is duplicated in a > few places, so add two utility functions to cover it. Also just use > perf_pmu__scan_file() instead of pmu_type() which already does the same > thing. > > No functional changes.
After I read the article: https://lwn.net/Articles/69419/, good to see this patch uses scnprintf() to replace snprintf().
> Signed-off-by: James Clark <james.clark@arm.com> > --- > tools/perf/arch/arm/util/auxtrace.c | 5 +- > tools/perf/arch/x86/util/pmu.c | 12 +-- > tools/perf/util/pmu.c | 110 +++++++++++----------------- > tools/perf/util/pmu.h | 5 +- > 4 files changed, 49 insertions(+), 83 deletions(-) > > diff --git a/tools/perf/arch/arm/util/auxtrace.c b/tools/perf/arch/arm/util/auxtrace.c > index deeb163999ce..3cb4a6a16112 100644 > --- a/tools/perf/arch/arm/util/auxtrace.c > +++ b/tools/perf/arch/arm/util/auxtrace.c > @@ -55,17 +55,16 @@ static struct perf_pmu **find_all_arm_spe_pmus(int *nr_spes, int *err) > > static struct perf_pmu **find_all_hisi_ptt_pmus(int *nr_ptts, int *err) > { > - const char *sysfs = sysfs__mountpoint(); > struct perf_pmu **hisi_ptt_pmus = NULL; > struct dirent *dent; > char path[PATH_MAX]; > DIR *dir = NULL; > int idx = 0; > > - snprintf(path, PATH_MAX, "%s" EVENT_SOURCE_DEVICE_PATH, sysfs); > + perf_pmu__event_source_devices_scnprintf(path, PATH_MAX);
Nitpick: since 'path' is an array, a good practice is to use 'sizeof(path)' rather than 'PATH_MAX' for passing the length.
> dir = opendir(path); > if (!dir) { > - pr_err("can't read directory '%s'\n", EVENT_SOURCE_DEVICE_PATH); > + pr_err("can't read directory '%s'\n", path); > *err = -EINVAL; > return NULL; > } > diff --git a/tools/perf/arch/x86/util/pmu.c b/tools/perf/arch/x86/util/pmu.c > index 74d69db1ea99..e3456d4b9063 100644 > --- a/tools/perf/arch/x86/util/pmu.c > +++ b/tools/perf/arch/x86/util/pmu.c > @@ -15,8 +15,6 @@ > #include "../../../util/pmu.h" > #include "../../../util/fncache.h" > > -#define TEMPLATE_ALIAS "%s/bus/event_source/devices/%s/alias" > - > struct pmu_alias { > char *name; > char *alias; > @@ -72,18 +70,14 @@ static int setup_pmu_alias_list(void) > char path[PATH_MAX]; > DIR *dir; > struct dirent *dent; > - const char *sysfs = sysfs__mountpoint(); > struct pmu_alias *pmu_alias; > char buf[MAX_PMU_NAME_LEN]; > FILE *file; > int ret = -ENOMEM; > > - if (!sysfs) > + if (!perf_pmu__event_source_devices_scnprintf(path, PATH_MAX)) > return -1; > > - snprintf(path, PATH_MAX, > - "%s" EVENT_SOURCE_DEVICE_PATH, sysfs); > - > dir = opendir(path); > if (!dir) > return -errno; > @@ -93,9 +87,7 @@ static int setup_pmu_alias_list(void) > !strcmp(dent->d_name, "..")) > continue; > > - snprintf(path, PATH_MAX, > - TEMPLATE_ALIAS, sysfs, dent->d_name); > - > + perf_pmu__pathname_scnprintf(path, PATH_MAX, dent->d_name, "alias"); > if (!file_available(path)) > continue; > > diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c > index 2bdeb89352e7..827c1a6bb99a 100644 > --- a/tools/perf/util/pmu.c > +++ b/tools/perf/util/pmu.c > @@ -107,14 +107,10 @@ int perf_pmu__format_parse(char *dir, struct list_head *head) > static int pmu_format(const char *name, struct list_head *format) > { > char path[PATH_MAX]; > - const char *sysfs = sysfs__mountpoint(); > > - if (!sysfs) > + if (!perf_pmu__pathname_scnprintf(path, PATH_MAX, name, "format")) > return -1; > > - snprintf(path, PATH_MAX, > - "%s" EVENT_SOURCE_DEVICE_PATH "%s/format", sysfs, name); > - > if (!file_available(path)) > return 0; > > @@ -513,14 +509,10 @@ static int pmu_aliases_parse(char *dir, struct list_head *head) > static int pmu_aliases(const char *name, struct list_head *head) > { > char path[PATH_MAX]; > - const char *sysfs = sysfs__mountpoint(); > > - if (!sysfs) > + if (!perf_pmu__pathname_scnprintf(path, PATH_MAX, name, "events")) > return -1; > > - snprintf(path, PATH_MAX, > - "%s/bus/event_source/devices/%s/events", sysfs, name); > - > if (!file_available(path)) > return 0; > > @@ -554,52 +546,16 @@ static int pmu_alias_terms(struct perf_pmu_alias *alias, > return 0; > } > > -/* > - * Reading/parsing the default pmu type value, which should be > - * located at: > - * /sys/bus/event_source/devices/<dev>/type as sysfs attribute. > - */ > -static int pmu_type(const char *name, __u32 *type) > -{ > - char path[PATH_MAX]; > - FILE *file; > - int ret = 0; > - const char *sysfs = sysfs__mountpoint(); > - > - if (!sysfs) > - return -1; > - > - snprintf(path, PATH_MAX, > - "%s" EVENT_SOURCE_DEVICE_PATH "%s/type", sysfs, name); > - > - if (access(path, R_OK) < 0) > - return -1; > - > - file = fopen(path, "r"); > - if (!file) > - return -EINVAL; > - > - if (1 != fscanf(file, "%u", type)) > - ret = -1; > - > - fclose(file); > - return ret; > -} > - > /* Add all pmus in sysfs to pmu list: */ > static void pmu_read_sysfs(void) > { > char path[PATH_MAX]; > DIR *dir; > struct dirent *dent; > - const char *sysfs = sysfs__mountpoint(); > > - if (!sysfs) > + if (!perf_pmu__event_source_devices_scnprintf(path, PATH_MAX)) > return; > > - snprintf(path, PATH_MAX, > - "%s" EVENT_SOURCE_DEVICE_PATH, sysfs); > - > dir = opendir(path); > if (!dir) > return; > @@ -696,14 +652,9 @@ static char *pmu_id(const char *name) > static int is_arm_pmu_core(const char *name) > { > char path[PATH_MAX]; > - const char *sysfs = sysfs__mountpoint(); > > - if (!sysfs) > + if (!perf_pmu__pathname_scnprintf(path, PATH_MAX, name, "cpus")) > return 0; > - > - /* Look for cpu sysfs (specific to arm) */ > - scnprintf(path, PATH_MAX, "%s/bus/event_source/devices/%s/cpus", > - sysfs, name); > return file_available(path); > } > > @@ -969,11 +920,8 @@ static struct perf_pmu *pmu_lookup(const char *lookup_name) > return NULL; > > /* > - * Check the type first to avoid unnecessary work. > + * Check the aliases first to avoid unnecessary work. > */ > - if (pmu_type(name, &type)) > - return NULL; > - > if (pmu_aliases(name, &aliases)) > return NULL; > > @@ -983,9 +931,14 @@ static struct perf_pmu *pmu_lookup(const char *lookup_name) > > pmu->cpus = pmu_cpumask(name); > pmu->name = strdup(name); > + > if (!pmu->name) > goto err; > > + /* Read type, and ensure that 1 value (type) is successfully assigned */
Maybe I don't understand well, seems to me a better comment is:
/* Read type, and ensure that type value is successfully assigned (return 1) */
The rest looks good to me. With addressing above two comments:
Reviewed-by: Leo Yan <leo.yan@linaro.org>
> + if (perf_pmu__scan_file(pmu, "type", "%u", &type) != 1) > + goto err; > + > alias_name = pmu_find_alias_name(name); > if (alias_name) { > pmu->alias_name = strdup(alias_name); > @@ -1786,16 +1739,11 @@ bool pmu_have_event(const char *pname, const char *name) > static FILE *perf_pmu__open_file(struct perf_pmu *pmu, const char *name) > { > char path[PATH_MAX]; > - const char *sysfs; > > - sysfs = sysfs__mountpoint(); > - if (!sysfs) > + if (!perf_pmu__pathname_scnprintf(path, PATH_MAX, pmu->name, name) || > + !file_available(path)) > return NULL; > > - snprintf(path, PATH_MAX, > - "%s" EVENT_SOURCE_DEVICE_PATH "%s/%s", sysfs, pmu->name, name); > - if (!file_available(path)) > - return NULL; > return fopen(path, "r"); > } > > @@ -1849,7 +1797,6 @@ int perf_pmu__caps_parse(struct perf_pmu *pmu) > { > struct stat st; > char caps_path[PATH_MAX]; > - const char *sysfs = sysfs__mountpoint(); > DIR *caps_dir; > struct dirent *evt_ent; > > @@ -1858,12 +1805,9 @@ int perf_pmu__caps_parse(struct perf_pmu *pmu) > > pmu->nr_caps = 0; > > - if (!sysfs) > + if (!perf_pmu__pathname_scnprintf(caps_path, PATH_MAX, pmu->name, "caps")) > return -1; > > - snprintf(caps_path, PATH_MAX, > - "%s" EVENT_SOURCE_DEVICE_PATH "%s/caps", sysfs, pmu->name); > - > if (stat(caps_path, &st) < 0) { > pmu->caps_initialized = true; > return 0; /* no error if caps does not exist */ > @@ -1993,3 +1937,31 @@ int perf_pmu__cpus_match(struct perf_pmu *pmu, struct perf_cpu_map *cpus, > *ucpus_ptr = unmatched_cpus; > return 0; > } > + > +int perf_pmu__event_source_devices_scnprintf(char *pathname, size_t size) > +{ > + const char *sysfs = sysfs__mountpoint(); > + > + if (!sysfs) > + return 0; > + return scnprintf(pathname, size, "%s/bus/event_source/devices/", sysfs); > +} > + > +/* > + * Fill 'buf' with the path to a file or folder in 'pmu_name' in > + * sysfs. For example if pmu_name = "cs_etm" and 'filename' = "format" > + * then pathname will be filled with > + * "/sys/bus/event_source/devices/cs_etm/format" > + * > + * Return 0 if the sysfs mountpoint couldn't be found or if no > + * characters were written. > + */ > +int perf_pmu__pathname_scnprintf(char *buf, size_t size, > + const char *pmu_name, const char *filename) > +{ > + char base_path[PATH_MAX]; > + > + if (!perf_pmu__event_source_devices_scnprintf(base_path, PATH_MAX)) > + return 0; > + return scnprintf(buf, size, "%s%s/%s", base_path, pmu_name, filename); > +} > diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h > index 69ca0004f94f..2f2bb0286e2a 100644 > --- a/tools/perf/util/pmu.h > +++ b/tools/perf/util/pmu.h > @@ -22,7 +22,6 @@ enum { > }; > > #define PERF_PMU_FORMAT_BITS 64 > -#define EVENT_SOURCE_DEVICE_PATH "/bus/event_source/devices/" > #define CPUS_TEMPLATE_CPU "%s/bus/event_source/devices/%s/cpus" > #define MAX_PMU_NAME_LEN 128 > > @@ -259,4 +258,8 @@ int perf_pmu__cpus_match(struct perf_pmu *pmu, struct perf_cpu_map *cpus, > > char *pmu_find_real_name(const char *name); > char *pmu_find_alias_name(const char *name); > +int perf_pmu__event_source_devices_scnprintf(char *pathname, size_t size); > +int perf_pmu__pathname_scnprintf(char *buf, size_t size, > + const char *pmu_name, const char *filename); > + > #endif /* __PMU_H */ > -- > 2.25.1 >
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