Re: [PATCH v3] drm/i915: Handle incomplete Z_FINISH for compressed error states

Tvrtko Ursulin
2018-10-03T09:04:09Z

On 03/10/2018 09:24, Chris Wilson wrote:
> The final call to zlib_deflate(Z_FINISH) may require more output
> space to be allocated and so needs to re-invoked. Failure to do so in
> the current code leads to incomplete zlib streams (albeit intact due to
> the use of Z_SYNC_FLUSH) resulting in the occasional short object
> capture.
>
> v2: Check against overrunning our pre-allocated page array
> v3: Drop Z_SYNC_FLUSH entirely
>
> Testcase: igt/i915-error-capture.js
> Fixes: 0a97015d45ee ("drm/i915: Compress GPU objects in error state")
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Cc: <stable@vger.kernel.org> # v4.10+
> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> ---
> drivers/gpu/drm/i915/i915_gpu_error.c | 88 +++++++++++++++++++--------
> drivers/gpu/drm/i915/i915_gpu_error.h | 1 +
> 2 files changed, 64 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
> index 3d5554f14dfd..705ff122100f 100644
> --- a/drivers/gpu/drm/i915/i915_gpu_error.c
> +++ b/drivers/gpu/drm/i915/i915_gpu_error.c
> @@ -232,6 +232,20 @@ static bool compress_init(struct compress *c)
> return true;
> }
>
> +static void *compress_next_page(struct drm_i915_error_object *dst)
> +{
> + unsigned long page;
> +
> + if (dst->page_count >= dst->num_pages)
> + return ERR_PTR(-ENOSPC);
> +
> + page = __get_free_page(GFP_ATOMIC | __GFP_NOWARN);
> + if (!page)
> + return ERR_PTR(-ENOMEM);
> +
> + return dst->pages[dst->page_count++] = (void *)page;
> +}
> +
> static int compress_page(struct compress *c,
> void *src,
> struct drm_i915_error_object *dst)
> @@ -245,19 +259,14 @@ static int compress_page(struct compress *c,
>
> do {
> if (zstream->avail_out == 0) {
> - unsigned long page;
> -
> - page = __get_free_page(GFP_ATOMIC | __GFP_NOWARN);
> - if (!page)
> - return -ENOMEM;
> + zstream->next_out = compress_next_page(dst);
> + if (IS_ERR(zstream->next_out))
> + return PTR_ERR(zstream->next_out);
>
> - dst->pages[dst->page_count++] = (void *)page;
> -
> - zstream->next_out = (void *)page;
> zstream->avail_out = PAGE_SIZE;
> }
>
> - if (zlib_deflate(zstream, Z_SYNC_FLUSH) != Z_OK)
> + if (zlib_deflate(zstream, Z_NO_FLUSH) != Z_OK)
> return -EIO;
> } while (zstream->avail_in);
>
> @@ -268,19 +277,42 @@ static int compress_page(struct compress *c,
> return 0;
> }
>
> -static void compress_fini(struct compress *c,
> +static int compress_flush(struct compress *c,
> struct drm_i915_error_object *dst)
> {
> struct z_stream_s *zstream = &c->zstream;
>
> - if (dst) {
> - zlib_deflate(zstream, Z_FINISH);
> - dst->unused = zstream->avail_out;
> - }
> + do {
> + switch (zlib_deflate(zstream, Z_FINISH)) {
> + case Z_OK: /* more space requested */
> + zstream->next_out = compress_next_page(dst);
> + if (IS_ERR(zstream->next_out))
> + return PTR_ERR(zstream->next_out);
> +
> + zstream->avail_out = PAGE_SIZE;
> + break;
> +
> + case Z_STREAM_END:
> + goto end;
> +
> + default: /* any error */
> + return -EIO;
> + }
> + } while (1);
> +
> +end:
> + memset(zstream->next_out, 0, zstream->avail_out);
> + dst->unused = zstream->avail_out;
> + return 0;
> +}
> +
> +static void compress_fini(struct compress *c,
> + struct drm_i915_error_object *dst)
> +{
> + struct z_stream_s *zstream = &c->zstream;
>
> zlib_deflateEnd(zstream);
> kfree(zstream->workspace);
> -
> if (c->tmp)
> free_page((unsigned long)c->tmp);
> }
> @@ -319,6 +351,12 @@ static int compress_page(struct compress *c,
> return 0;
> }
>
> +static int compress_flush(struct compress *c,
> + struct drm_i915_error_object *dst)
> +{
> + return 0;
> +}
> +
> static void compress_fini(struct compress *c,
> struct drm_i915_error_object *dst)
> {
> @@ -917,6 +955,7 @@ i915_error_object_create(struct drm_i915_private *i915,
> unsigned long num_pages;
> struct sgt_iter iter;
> dma_addr_t dma;
> + int ret;
>
> if (!vma)
> return NULL;
> @@ -930,6 +969,7 @@ i915_error_object_create(struct drm_i915_private *i915,
>
> dst->gtt_offset = vma->node.start;
> dst->gtt_size = vma->node.size;
> + dst->num_pages = num_pages;
> dst->page_count = 0;
> dst->unused = 0;
>
> @@ -938,28 +978,26 @@ i915_error_object_create(struct drm_i915_private *i915,
> return NULL;
> }
>
> + ret = -EINVAL;
> for_each_sgt_dma(dma, iter, vma->pages) > void __iomem *s;
> - int ret;
>
> ggtt->vm.insert_page(&ggtt->vm, dma, slot, I915_CACHE_NONE, 0);
>
> s = io_mapping_map_atomic_wc(&ggtt->iomap, slot);
> ret = compress_page(&compress, (void __force *)s, dst);
> io_mapping_unmap_atomic(s);
> -
> if (ret)
> - goto unwind;
> + break;
> }
> - goto out;
>
> -unwind:
> - while (dst->page_count--)
> - free_page((unsigned long)dst->pages[dst->page_count]);
> - kfree(dst);
> - dst = NULL;
> + if (ret || compress_flush(&compress, dst)) {
> + while (dst->page_count--)
> + free_page((unsigned long)dst->pages[dst->page_count]);
> + kfree(dst);
> + dst = NULL;
> + }
>
> -out:
> compress_fini(&compress, dst);
> ggtt->vm.clear_range(&ggtt->vm, slot, PAGE_SIZE);
> return dst;
> diff --git a/drivers/gpu/drm/i915/i915_gpu_error.h b/drivers/gpu/drm/i915/i915_gpu_error.h
> index f893a4e8b783..8710fb18ed74 100644
> --- a/drivers/gpu/drm/i915/i915_gpu_error.h
> +++ b/drivers/gpu/drm/i915/i915_gpu_error.h
> @@ -135,6 +135,7 @@ struct i915_gpu_state {
> struct drm_i915_error_object {
> u64 gtt_offset;
> u64 gtt_size;
> + int num_pages;
> int page_count;
> int unused;
> u32 *pages[0];
>

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Regards,

Tvrtko