Re: [PATCH v4 01/10] KVM: selftests: Remove dynamic memory allocation for stats header

[Mingwei Zhang]

On Mon, Apr 11, 2022, David Matlack wrote:
> On Mon, Apr 11, 2022 at 2:10 PM Ben Gardon <bgardon@xxxxxxxxxx> wrote:
> >
> > There's no need to allocate dynamic memory for the stats header since
> > its size is known at compile time.
> >
> > Signed-off-by: Ben Gardon <bgardon@xxxxxxxxxx>
> 
> Reviewed-by: David Matlack <dmatlack@xxxxxxxxxx>
> 
Reviewed-by: Mingwei Zhang <mizhang@xxxxxxxxxx>
> > ---
> >  .../selftests/kvm/kvm_binary_stats_test.c     | 58 +++++++++----------
> >  1 file changed, 27 insertions(+), 31 deletions(-)
> >
> > diff --git a/tools/testing/selftests/kvm/kvm_binary_stats_test.c b/tools/testing/selftests/kvm/kvm_binary_stats_test.c
> > index 17f65d514915..dad34d8a41fe 100644
> > --- a/tools/testing/selftests/kvm/kvm_binary_stats_test.c
> > +++ b/tools/testing/selftests/kvm/kvm_binary_stats_test.c
> > @@ -26,56 +26,53 @@ static void stats_test(int stats_fd)
> >         int i;
> >         size_t size_desc;
> >         size_t size_data = 0;
> > -       struct kvm_stats_header *header;
> > +       struct kvm_stats_header header;
> >         char *id;
> >         struct kvm_stats_desc *stats_desc;
> >         u64 *stats_data;
> >         struct kvm_stats_desc *pdesc;
> >
> >         /* Read kvm stats header */
> > -       header = malloc(sizeof(*header));
> > -       TEST_ASSERT(header, "Allocate memory for stats header");
> > -
> > -       ret = read(stats_fd, header, sizeof(*header));
> > -       TEST_ASSERT(ret == sizeof(*header), "Read stats header");
> > -       size_desc = sizeof(*stats_desc) + header->name_size;
> > +       ret = read(stats_fd, &header, sizeof(header));
> > +       TEST_ASSERT(ret == sizeof(header), "Read stats header");
> > +       size_desc = sizeof(*stats_desc) + header.name_size;
> >
> >         /* Read kvm stats id string */
> > -       id = malloc(header->name_size);
> > +       id = malloc(header.name_size);
> >         TEST_ASSERT(id, "Allocate memory for id string");
> > -       ret = read(stats_fd, id, header->name_size);
> > -       TEST_ASSERT(ret == header->name_size, "Read id string");
> > +       ret = read(stats_fd, id, header.name_size);
> > +       TEST_ASSERT(ret == header.name_size, "Read id string");
> >
> >         /* Check id string, that should start with "kvm" */
> > -       TEST_ASSERT(!strncmp(id, "kvm", 3) && strlen(id) < header->name_size,
> > +       TEST_ASSERT(!strncmp(id, "kvm", 3) && strlen(id) < header.name_size,
> >                                 "Invalid KVM stats type, id: %s", id);
> >
> >         /* Sanity check for other fields in header */
> > -       if (header->num_desc == 0) {
> > +       if (header.num_desc == 0) {
> >                 printf("No KVM stats defined!");
> >                 return;
> >         }
> >         /* Check overlap */
> > -       TEST_ASSERT(header->desc_offset > 0 && header->data_offset > 0
> > -                       && header->desc_offset >= sizeof(*header)
> > -                       && header->data_offset >= sizeof(*header),
> > +       TEST_ASSERT(header.desc_offset > 0 && header.data_offset > 0
> > +                       && header.desc_offset >= sizeof(header)
> > +                       && header.data_offset >= sizeof(header),
> >                         "Invalid offset fields in header");
> > -       TEST_ASSERT(header->desc_offset > header->data_offset ||
> > -                       (header->desc_offset + size_desc * header->num_desc <=
> > -                                                       header->data_offset),
> > +       TEST_ASSERT(header.desc_offset > header.data_offset ||
> > +                       (header.desc_offset + size_desc * header.num_desc <=
> > +                                                       header.data_offset),
> >                         "Descriptor block is overlapped with data block");
> >
> >         /* Allocate memory for stats descriptors */
> > -       stats_desc = calloc(header->num_desc, size_desc);
> > +       stats_desc = calloc(header.num_desc, size_desc);
> >         TEST_ASSERT(stats_desc, "Allocate memory for stats descriptors");
> >         /* Read kvm stats descriptors */
> >         ret = pread(stats_fd, stats_desc,
> > -                       size_desc * header->num_desc, header->desc_offset);
> > -       TEST_ASSERT(ret == size_desc * header->num_desc,
> > +                       size_desc * header.num_desc, header.desc_offset);
> > +       TEST_ASSERT(ret == size_desc * header.num_desc,
> >                         "Read KVM stats descriptors");
> >
> >         /* Sanity check for fields in descriptors */
> > -       for (i = 0; i < header->num_desc; ++i) {
> > +       for (i = 0; i < header.num_desc; ++i) {
> >                 pdesc = (void *)stats_desc + i * size_desc;
> >                 /* Check type,unit,base boundaries */
> >                 TEST_ASSERT((pdesc->flags & KVM_STATS_TYPE_MASK)
> > @@ -104,7 +101,7 @@ static void stats_test(int stats_fd)
> >                         break;
> >                 }
> >                 /* Check name string */
> > -               TEST_ASSERT(strlen(pdesc->name) < header->name_size,
> > +               TEST_ASSERT(strlen(pdesc->name) < header.name_size,
> >                                 "KVM stats name(%s) too long", pdesc->name);
> >                 /* Check size field, which should not be zero */
> >                 TEST_ASSERT(pdesc->size, "KVM descriptor(%s) with size of 0",
> > @@ -124,14 +121,14 @@ static void stats_test(int stats_fd)
> >                 size_data += pdesc->size * sizeof(*stats_data);
> >         }
> >         /* Check overlap */
> > -       TEST_ASSERT(header->data_offset >= header->desc_offset
> > -               || header->data_offset + size_data <= header->desc_offset,
> > +       TEST_ASSERT(header.data_offset >= header.desc_offset
> > +               || header.data_offset + size_data <= header.desc_offset,
> >                 "Data block is overlapped with Descriptor block");
> >         /* Check validity of all stats data size */
> > -       TEST_ASSERT(size_data >= header->num_desc * sizeof(*stats_data),
> > +       TEST_ASSERT(size_data >= header.num_desc * sizeof(*stats_data),
> >                         "Data size is not correct");
> >         /* Check stats offset */
> > -       for (i = 0; i < header->num_desc; ++i) {
> > +       for (i = 0; i < header.num_desc; ++i) {
> >                 pdesc = (void *)stats_desc + i * size_desc;
> >                 TEST_ASSERT(pdesc->offset < size_data,
> >                         "Invalid offset (%u) for stats: %s",
> > @@ -142,15 +139,15 @@ static void stats_test(int stats_fd)
> >         stats_data = malloc(size_data);
> >         TEST_ASSERT(stats_data, "Allocate memory for stats data");
> >         /* Read kvm stats data as a bulk */
> > -       ret = pread(stats_fd, stats_data, size_data, header->data_offset);
> > +       ret = pread(stats_fd, stats_data, size_data, header.data_offset);
> >         TEST_ASSERT(ret == size_data, "Read KVM stats data");
> >         /* Read kvm stats data one by one */
> >         size_data = 0;
> > -       for (i = 0; i < header->num_desc; ++i) {
> > +       for (i = 0; i < header.num_desc; ++i) {
> >                 pdesc = (void *)stats_desc + i * size_desc;
> >                 ret = pread(stats_fd, stats_data,
> >                                 pdesc->size * sizeof(*stats_data),
> > -                               header->data_offset + size_data);
> > +                               header.data_offset + size_data);
> >                 TEST_ASSERT(ret == pdesc->size * sizeof(*stats_data),
> >                                 "Read data of KVM stats: %s", pdesc->name);
> >                 size_data += pdesc->size * sizeof(*stats_data);
> > @@ -159,7 +156,6 @@ static void stats_test(int stats_fd)
> >         free(stats_data);
> >         free(stats_desc);
> >         free(id);
> > -       free(header);
> >  }
> >
> >
> > --
> > 2.35.1.1178.g4f1659d476-goog
> >