Messages in this thread | | | From | Ian Rogers <> | Date | Mon, 9 Oct 2023 09:33:32 -0700 | Subject | Re: [PATCH v2 07/18] perf env: Remove unnecessary NULL tests |
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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 > >
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