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charset="UTF-8" Guard lazy initialization of kernel_is_64_bit, nr_cpus_avail, e_machine, cpuid, nr_pmu_mappings, pmu_mappings, and numa_map in struct perf_env with env->lock, and use DO_ONCE() to initialize the cached host utsname structure. This prevents data races when multiple threads concurrently query a shared struct perf_env. Signed-off-by: Ian Rogers --- tools/perf/util/env.c | 178 +++++++++++++++++++++++++------------- tools/perf/util/session.c | 15 +++- 2 files changed, 131 insertions(+), 62 deletions(-) diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c index 50993b0dedc5..4ab46ca6b4ef 100644 --- a/tools/perf/util/env.c +++ b/tools/perf/util/env.c @@ -313,18 +313,17 @@ void perf_env__init(struct perf_env *env) mutex_init(&env->lock); } -static void perf_env__init_kernel_mode(struct perf_env *env) +static const char *uts_machine(void) { - const char *arch = env->arch; + static struct utsname uts; - if (!arch) { - static struct utsname uts = { .machine[0] = '\0', }; + DO_ONCE(uname, &uts); + return uts.machine[0] != '\0' ? uts.machine : NULL; +} - if (uts.machine[0] == '\0') - uname(&uts); - if (uts.machine[0] != '\0') - arch = uts.machine; - } +static void perf_env__init_kernel_mode(struct perf_env *env) +{ + const char *arch = env->arch ?: uts_machine(); if (arch) { if (strstr(arch, "64") || strstr(arch, "s390x")) @@ -340,10 +339,15 @@ static void perf_env__init_kernel_mode(struct perf_env *env) int perf_env__kernel_is_64_bit(struct perf_env *env) { + int is_64_bit; + + mutex_lock(&env->lock); if (env->kernel_is_64_bit == -1) perf_env__init_kernel_mode(env); + is_64_bit = env->kernel_is_64_bit; + mutex_unlock(&env->lock); - return env->kernel_is_64_bit; + return is_64_bit; } bool perf_arch_is_big_endian(const char *arch) @@ -474,7 +478,6 @@ int perf_env__read_pmu_mappings(struct perf_env *env) pr_debug("pmu mappings not available\n"); return -ENOENT; } - env->nr_pmu_mappings = pmu_num; if (strbuf_init(&sb, 128 * pmu_num) < 0) return -ENOMEM; @@ -488,6 +491,7 @@ int perf_env__read_pmu_mappings(struct perf_env *env) } env->pmu_mappings = strbuf_detach(&sb, NULL); + env->nr_pmu_mappings = pmu_num; return 0; @@ -632,7 +636,17 @@ int perf_env__read_core_pmu_caps(struct perf_env *env) int perf_env__nr_cpus_avail(struct perf_env *env) { - return env && !perf_env__read_nr_cpus_avail(env) ? env->nr_cpus_avail : 0; + int nr_cpus = 0; + + if (!env) + return 0; + + mutex_lock(&env->lock); + if (!perf_env__read_nr_cpus_avail(env)) + nr_cpus = env->nr_cpus_avail; + mutex_unlock(&env->lock); + + return nr_cpus; } void cpu_cache_level__free(struct cpu_cache_level *cache) @@ -780,7 +794,7 @@ static const char *e_machine_to_perf_arch(uint16_t e_machine) return "unknown"; } -uint16_t perf_env__e_machine_nocache(struct perf_env *env, uint32_t *e_flags) +static uint16_t __perf_env__e_machine_nocache(struct perf_env *env, uint32_t *e_flags) { uint16_t e_machine = EM_NONE; const char *arch = NULL; @@ -794,14 +808,8 @@ uint16_t perf_env__e_machine_nocache(struct perf_env *env, uint32_t *e_flags) is_64_bit = env->kernel_is_64_bit; } - if (!arch) { - static struct utsname uts = { .machine[0] = '\0', }; - - if (uts.machine[0] == '\0') - uname(&uts); - if (uts.machine[0] != '\0') - arch = uts.machine; - } + if (!arch) + arch = uts_machine(); e_machine = perf_arch_to_e_machine(arch, is_64_bit); @@ -811,18 +819,37 @@ uint16_t perf_env__e_machine_nocache(struct perf_env *env, uint32_t *e_flags) return e_machine; } +uint16_t perf_env__e_machine_nocache(struct perf_env *env, uint32_t *e_flags) +{ + uint16_t e_machine; + + if (!env) + return __perf_env__e_machine_nocache(NULL, e_flags); + + mutex_lock(&env->lock); + e_machine = __perf_env__e_machine_nocache(env, e_flags); + mutex_unlock(&env->lock); + + return e_machine; +} + uint16_t perf_env__e_machine(struct perf_env *env, uint32_t *e_flags) { uint16_t e_machine; uint32_t local_e_flags = 0; - if (env && env->e_machine != EM_NONE) { + if (!env) + return __perf_env__e_machine_nocache(NULL, e_flags); + + mutex_lock(&env->lock); + if (env->e_machine != EM_NONE) { if (e_flags) *e_flags = env->e_flags; - - return env->e_machine; + e_machine = env->e_machine; + mutex_unlock(&env->lock); + return e_machine; } - e_machine = perf_env__e_machine_nocache(env, &local_e_flags); + e_machine = __perf_env__e_machine_nocache(env, &local_e_flags); /* * Only cache the e_machine in perf_env if env->arch is not NULL. * If env->arch is NULL, the e_machine is just a fallback to EM_HOST. @@ -830,10 +857,12 @@ uint16_t perf_env__e_machine(struct perf_env *env, uint32_t *e_flags) * thread-based session e_machine scanning later in * perf_session__e_machine(). */ - if (env && env->arch) { + if (env->arch) { env->e_machine = e_machine; env->e_flags = local_e_flags; } + mutex_unlock(&env->lock); + if (e_flags) *e_flags = local_e_flags; @@ -846,13 +875,11 @@ const char *perf_env__arch(struct perf_env *env) const char *arch; if (!env) { - static struct utsname uts = { .machine[0] = '\0', }; - uint16_t host_e_machine; + const char *host_arch = uts_machine(); + + if (host_arch) { + uint16_t host_e_machine = perf_arch_to_e_machine(host_arch, -1); - if (uts.machine[0] == '\0') - uname(&uts); - if (uts.machine[0] != '\0') { - host_e_machine = perf_arch_to_e_machine(uts.machine, -1); return e_machine_to_perf_arch(host_e_machine); } return e_machine_to_perf_arch(EM_HOST); @@ -884,45 +911,60 @@ const char *perf_env__arch_strerrno(uint16_t e_machine, int err) const char *perf_env__cpuid(struct perf_env *env) { - int status; + const char *cpuid; + mutex_lock(&env->lock); if (!env->cpuid) { /* Assume local operation */ - status = perf_env__read_cpuid(env); - if (status) + if (perf_env__read_cpuid(env)) { + mutex_unlock(&env->lock); return NULL; + } } + cpuid = env->cpuid; + mutex_unlock(&env->lock); - return env->cpuid; + return cpuid; } int perf_env__nr_pmu_mappings(struct perf_env *env) { - int status; + int nr; + mutex_lock(&env->lock); if (!env->nr_pmu_mappings) { /* Assume local operation */ - status = perf_env__read_pmu_mappings(env); - if (status) + if (perf_env__read_pmu_mappings(env)) { + mutex_unlock(&env->lock); return 0; + } } + nr = env->nr_pmu_mappings; + mutex_unlock(&env->lock); - return env->nr_pmu_mappings; + return nr; } const char *perf_env__pmu_mappings(struct perf_env *env) { - int status; + const char *mappings; + mutex_lock(&env->lock); if (!env->pmu_mappings) { /* Assume local operation */ - status = perf_env__read_pmu_mappings(env); - if (status) + if (perf_env__read_pmu_mappings(env)) { + mutex_unlock(&env->lock); return NULL; + } } + mappings = env->pmu_mappings; + mutex_unlock(&env->lock); - return env->pmu_mappings; + return mappings; } int perf_env__numa_node(struct perf_env *env, struct perf_cpu cpu) { + int node; + + mutex_lock(&env->lock); if (!env->nr_numa_map) { struct numa_node *nn; int i, nr = 0; @@ -939,8 +981,10 @@ int perf_env__numa_node(struct perf_env *env, struct perf_cpu cpu) * it for missing cpus, which return node -1 */ env->numa_map = malloc(nr * sizeof(int)); - if (!env->numa_map) + if (!env->numa_map) { + mutex_unlock(&env->lock); return -1; + } for (i = 0; i < nr; i++) env->numa_map[i] = -1; @@ -957,25 +1001,37 @@ int perf_env__numa_node(struct perf_env *env, struct perf_cpu cpu) } } - return cpu.cpu >= 0 && cpu.cpu < env->nr_numa_map ? env->numa_map[cpu.cpu] : -1; + node = cpu.cpu >= 0 && cpu.cpu < env->nr_numa_map ? env->numa_map[cpu.cpu] : -1; + mutex_unlock(&env->lock); + + return node; } bool perf_env__has_pmu_mapping(struct perf_env *env, const char *pmu_name) { - char *pmu_mapping = env->pmu_mappings, *colon; + char *pmu_mapping, *colon; + bool ret = false; + + mutex_lock(&env->lock); + pmu_mapping = env->pmu_mappings; + if (!pmu_mapping) + goto out_unlock; for (int i = 0; i < env->nr_pmu_mappings; ++i) { if (strtoul(pmu_mapping, &colon, 0) == ULONG_MAX || *colon != ':') - goto out_error; + goto out_unlock; pmu_mapping = colon + 1; - if (strcmp(pmu_mapping, pmu_name) == 0) - return true; + if (strcmp(pmu_mapping, pmu_name) == 0) { + ret = true; + break; + } pmu_mapping += strlen(pmu_mapping) + 1; } -out_error: - return false; +out_unlock: + mutex_unlock(&env->lock); + return ret; } char *perf_env__find_pmu_cap(struct perf_env *env, const char *pmu_name, @@ -1043,12 +1099,13 @@ void perf_env__find_br_cntr_info(struct perf_env *env, bool perf_env__is_x86_amd_cpu(struct perf_env *env) { - static int is_amd; /* 0: Uninitialized, 1: Yes, -1: No */ + bool is_amd; - if (is_amd == 0) - is_amd = env->cpuid && strstarts(env->cpuid, "AuthenticAMD") ? 1 : -1; + mutex_lock(&env->lock); + is_amd = env->cpuid && strstarts(env->cpuid, "AuthenticAMD"); + mutex_unlock(&env->lock); - return is_amd >= 1 ? true : false; + return is_amd; } bool x86__is_amd_cpu(void) @@ -1066,12 +1123,13 @@ bool x86__is_amd_cpu(void) bool perf_env__is_x86_intel_cpu(struct perf_env *env) { - static int is_intel; /* 0: Uninitialized, 1: Yes, -1: No */ + bool is_intel; - if (is_intel == 0) - is_intel = env->cpuid && strstarts(env->cpuid, "GenuineIntel") ? 1 : -1; + mutex_lock(&env->lock); + is_intel = env->cpuid && strstarts(env->cpuid, "GenuineIntel"); + mutex_unlock(&env->lock); - return is_intel >= 1 ? true : false; + return is_intel; } bool x86__is_intel_cpu(void) diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c index 56a5e57ec512..f35d6867e816 100644 --- a/tools/perf/util/session.c +++ b/tools/perf/util/session.c @@ -4235,8 +4235,17 @@ uint16_t perf_session__e_machine(struct perf_session *session, uint32_t *e_flags * more accurate threads. */ env = perf_session__env(session); - if (env && env->e_machine != EM_NONE) - return perf_env__e_machine(env, e_flags); + if (env) { + uint16_t e_machine; + + mutex_lock(&env->lock); + e_machine = env->e_machine; + if (e_machine != EM_NONE && e_flags) + *e_flags = env->e_flags; + mutex_unlock(&env->lock); + if (e_machine != EM_NONE) + return e_machine; + } /* * Compute from threads, note this is more accurate than @@ -4249,8 +4258,10 @@ uint16_t perf_session__e_machine(struct perf_session *session, uint32_t *e_flags if (args.e_machine != EM_NONE) { if (env) { + mutex_lock(&env->lock); env->e_machine = args.e_machine; env->e_flags = args.e_flags; + mutex_unlock(&env->lock); } if (e_flags) *e_flags = args.e_flags; -- 2.56.1.703.gf848ed807c-goog