[igt-dev] [PATCH i-g-t] i915/gem_create: Verify that all new objects are clear

[Matthew Auld]

On Thu, 14 Feb 2019 at 18:32, Chris Wilson <chris at chris-wilson.co.uk> wrote:
>
> The kernel must not return stale information back to userspace when they
> create a new object. For that purpose, we always clear objects on
> creation, so verify that this is so.
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Matthew Auld <matthew.auld at intel.com>
> ---
>  tests/i915/gem_create.c | 71 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 71 insertions(+)
>
> diff --git a/tests/i915/gem_create.c b/tests/i915/gem_create.c
> index 25c5e8088..9de2263d5 100644
> --- a/tests/i915/gem_create.c
> +++ b/tests/i915/gem_create.c
> @@ -44,6 +44,7 @@
>  #include <sys/stat.h>
>  #include <sys/time.h>
>  #include <getopt.h>
> +#include <pthread.h>
>
>  #include <drm.h>
>
> @@ -141,6 +142,73 @@ static void invalid_nonaligned_size(int fd)
>         gem_close(fd, handle);
>  }
>
> +static uint64_t get_npages(uint64_t *global, uint64_t npages)
> +{
> +       uint64_t try, old, max;
> +
> +       max = *global;
> +       do {
> +               old = max;
> +               try = npages % (max / 2);
> +               max -= try;
> +       } while ((max = __sync_val_compare_and_swap(global, old, max)) != old);
> +
> +       return try;
> +}
> +
> +struct thread_clear {
> +       uint64_t max;
> +       int timeout;
> +       int i915;
> +};
> +
> +static void *thread_clear(void *data)
> +{
> +       struct thread_clear *arg = data;
> +       int i915 = arg->i915;
> +
> +       igt_until_timeout(arg->timeout) {
> +               uint32_t handle;
> +               uint64_t npages;
> +
> +               npages = random();
> +               npages <<= 32;
> +               npages |= random();
> +               npages = get_npages(&arg->max, npages);
> +
> +               handle = gem_create(i915, npages << 12);
> +               for (uint64_t page = 0; page < npages; page++) {
> +                       uint64_t x;
> +
> +                       gem_read(i915, handle,
> +                                       page % (4096 - sizeof(x)),
> +                                       &x, sizeof(x));

Don't we also want to read some values outside of the first page, or
am I missing something?

> +                       igt_assert_eq_u64(x, 0);
> +               }
> +               gem_close(i915, handle);
> +
> +               __sync_add_and_fetch(&arg->max, npages);
> +       }
> +
> +       return NULL;
> +}
> +
> +static void always_clear(int i915, int timeout)
> +{
> +       struct thread_clear arg = {
> +               .i915 = i915,
> +               .timeout = timeout,
> +               .max = intel_get_avail_ram_mb() << (20 - 12), /* in pages */
> +       };
> +       const int ncpus = sysconf(_SC_NPROCESSORS_ONLN);
> +       pthread_t thread[ncpus];
> +
> +       for (int i = 0; i < ncpus; i++)
> +               pthread_create(&thread[i], NULL, thread_clear, &arg);
> +       for (int i = 0; i < ncpus; i++)
> +               pthread_join(thread[i], NULL);
> +}
> +
>  igt_main
>  {
>         int fd = -1;
> @@ -162,4 +230,7 @@ igt_main
>
>         igt_subtest("create-invalid-nonaligned")
>                 invalid_nonaligned_size(fd);
> +
> +       igt_subtest("create-clear")
> +               always_clear(fd, 30);
>  }
> --
> 2.20.1
>
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