[PATCH v2] drm/i915: Handle incomplete Z_FINISH for compressed error states

Chris Wilson
2018-10-02T12:36:56Z

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

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 | 92 +++++++++++++++++++--------
drivers/gpu/drm/i915/i915_gpu_error.h | 1 +
2 files changed, 68 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..1035298e9a82 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -232,11 +232,26 @@ 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)
{
struct z_stream_s *zstream = &c->zstream;
+ int flush = Z_NO_FLUSH;

zstream->next_in = src;
if (c->tmp && i915_memcpy_from_wc(c->tmp, src, PAGE_SIZE))
@@ -245,20 +260,18 @@ 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, flush) != Z_OK)
return -EIO;
+
+ if (zstream->avail_out)
+ flush = Z_SYNC_FLUSH;
} while (zstream->avail_in);

/* Fallback to uncompressed if we increase size? */
@@ -268,19 +281,42 @@ 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 +355,12 @@ 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 +959,7 @@ 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 +973,7 @@ 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 +982,26 @@ 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];
--
2.19.0