| Message ID | 20231005230851.3666908-8-irogers@google.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | clang-tools support in tools | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
On Thu, Oct 5, 2023 at 4:09 PM Ian Rogers <irogers@google.com> wrote: > > clang-tidy was warning: > ``` > util/env.c:334:23: warning: Access to field 'nr_pmu_mappings' results in a dereference of a null pointer (loaded from variable 'env') [clang-analyzer-core.NullDereference] > env->nr_pmu_mappings = pmu_num; > ``` > > As functions are called potentially when !env was true. This condition > could never be true as it would produce a segv, so remove the > unnecessary NULL tests and silence clang-tidy. IIRC !env was to handle live sessions like perf top or when it doesn't have a perf data file. Anyway, it doesn't seem to work anymore. Thanks, Namhyung > > Signed-off-by: Ian Rogers <irogers@google.com> > --- > tools/perf/util/env.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c > index a164164001fb..44140b7f596a 100644 > --- a/tools/perf/util/env.c > +++ b/tools/perf/util/env.c > @@ -457,7 +457,7 @@ const char *perf_env__cpuid(struct perf_env *env) > { > int status; > > - if (!env || !env->cpuid) { /* Assume local operation */ > + if (!env->cpuid) { /* Assume local operation */ > status = perf_env__read_cpuid(env); > if (status) > return NULL; > @@ -470,7 +470,7 @@ int perf_env__nr_pmu_mappings(struct perf_env *env) > { > int status; > > - if (!env || !env->nr_pmu_mappings) { /* Assume local operation */ > + if (!env->nr_pmu_mappings) { /* Assume local operation */ > status = perf_env__read_pmu_mappings(env); > if (status) > return 0; > @@ -483,7 +483,7 @@ const char *perf_env__pmu_mappings(struct perf_env *env) > { > int status; > > - if (!env || !env->pmu_mappings) { /* Assume local operation */ > + if (!env->pmu_mappings) { /* Assume local operation */ > status = perf_env__read_pmu_mappings(env); > if (status) > return NULL; > -- > 2.42.0.609.gbb76f46606-goog >
On Sun, Oct 8, 2023 at 11:14 PM Namhyung Kim <namhyung@kernel.org> wrote: > > On Thu, Oct 5, 2023 at 4:09 PM Ian Rogers <irogers@google.com> wrote: > > > > clang-tidy was warning: > > ``` > > util/env.c:334:23: warning: Access to field 'nr_pmu_mappings' results in a dereference of a null pointer (loaded from variable 'env') [clang-analyzer-core.NullDereference] > > env->nr_pmu_mappings = pmu_num; > > ``` > > > > As functions are called potentially when !env was true. This condition > > could never be true as it would produce a segv, so remove the > > unnecessary NULL tests and silence clang-tidy. > > IIRC !env was to handle live sessions like perf top > or when it doesn't have a perf data file. Anyway, > it doesn't seem to work anymore. I trust the analyzer here and it would be better to crash earlier, from env being NULL, than in a particular conditional branch. Like you, I wasn't able to find a failure from removing the checks. Thanks, Ian > Thanks, > Namhyung > > > > > Signed-off-by: Ian Rogers <irogers@google.com> > > --- > > tools/perf/util/env.c | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c > > index a164164001fb..44140b7f596a 100644 > > --- a/tools/perf/util/env.c > > +++ b/tools/perf/util/env.c > > @@ -457,7 +457,7 @@ const char *perf_env__cpuid(struct perf_env *env) > > { > > int status; > > > > - if (!env || !env->cpuid) { /* Assume local operation */ > > + if (!env->cpuid) { /* Assume local operation */ > > status = perf_env__read_cpuid(env); > > if (status) > > return NULL; > > @@ -470,7 +470,7 @@ int perf_env__nr_pmu_mappings(struct perf_env *env) > > { > > int status; > > > > - if (!env || !env->nr_pmu_mappings) { /* Assume local operation */ > > + if (!env->nr_pmu_mappings) { /* Assume local operation */ > > status = perf_env__read_pmu_mappings(env); > > if (status) > > return 0; > > @@ -483,7 +483,7 @@ const char *perf_env__pmu_mappings(struct perf_env *env) > > { > > int status; > > > > - if (!env || !env->pmu_mappings) { /* Assume local operation */ > > + if (!env->pmu_mappings) { /* Assume local operation */ > > status = perf_env__read_pmu_mappings(env); > > if (status) > > return NULL; > > -- > > 2.42.0.609.gbb76f46606-goog > >
diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c index a164164001fb..44140b7f596a 100644 --- a/tools/perf/util/env.c +++ b/tools/perf/util/env.c @@ -457,7 +457,7 @@ const char *perf_env__cpuid(struct perf_env *env) { int status; - if (!env || !env->cpuid) { /* Assume local operation */ + if (!env->cpuid) { /* Assume local operation */ status = perf_env__read_cpuid(env); if (status) return NULL; @@ -470,7 +470,7 @@ int perf_env__nr_pmu_mappings(struct perf_env *env) { int status; - if (!env || !env->nr_pmu_mappings) { /* Assume local operation */ + if (!env->nr_pmu_mappings) { /* Assume local operation */ status = perf_env__read_pmu_mappings(env); if (status) return 0; @@ -483,7 +483,7 @@ const char *perf_env__pmu_mappings(struct perf_env *env) { int status; - if (!env || !env->pmu_mappings) { /* Assume local operation */ + if (!env->pmu_mappings) { /* Assume local operation */ status = perf_env__read_pmu_mappings(env); if (status) return NULL;
clang-tidy was warning: ``` util/env.c:334:23: warning: Access to field 'nr_pmu_mappings' results in a dereference of a null pointer (loaded from variable 'env') [clang-analyzer-core.NullDereference] env->nr_pmu_mappings = pmu_num; ``` As functions are called potentially when !env was true. This condition could never be true as it would produce a segv, so remove the unnecessary NULL tests and silence clang-tidy. Signed-off-by: Ian Rogers <irogers@google.com> --- tools/perf/util/env.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)