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References: <20220411211015.3091615-1-bgardon@google.com> <20220411211015.3091615-2-bgardon@google.com>
In-Reply-To: <20220411211015.3091615-2-bgardon@google.com>
From:   David Matlack <dmatlack@google.com>
Date:   Mon, 11 Apr 2022 14:52:24 -0700
Message-ID: <CALzav=d_DB+onkMZmZwEj7yd_gDqg_phqQJpTw0g9ahe3WmvqA@mail.gmail.com>
Subject: Re: [PATCH v4 01/10] KVM: selftests: Remove dynamic memory allocation
 for stats header
To:     Ben Gardon <bgardon@google.com>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        kvm list <kvm@vger.kernel.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Peter Xu <peterx@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Peter Shier <pshier@google.com>,
        David Dunn <daviddunn@google.com>,
        Junaid Shahid <junaids@google.com>,
        Jim Mattson <jmattson@google.com>,
        Mingwei Zhang <mizhang@google.com>,
        Jing Zhang <jingzhangos@google.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Mon, Apr 11, 2022 at 2:10 PM Ben Gardon <bgardon@google.com> 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@google.com>

Reviewed-by: David Matlack <dmatlack@google.com>

> ---
>  .../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
>