[PATCH 2/4] drm/i915: Handle incomplete Z_FINISH for compressed error states

Chris Wilson
2018-10-01T19:44:45Z

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.

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+
---
drivers/gpu/drm/i915/i915_gpu_error.c | 60 +++++++++++++++++++++------
1 file changed, 47 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index 3d5554f14dfd..ed8c16cbfaa4 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -237,6 +237,7 @@ static int compress_page(struct compress *c,
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))
@@ -257,8 +258,11 @@ static int compress_page(struct compress *c,
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 +272,43 @@ 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;
+ unsigned long page;

- 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 */
+ page = __get_free_page(GFP_ATOMIC | __GFP_NOWARN);
+ if (!page)
+ return -ENOMEM;
+
+ dst->pages[dst->page_count++] = (void *)page;
+ zstream->next_out = (void *)page;
+ 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 +347,12 @@ 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)
{
@@ -951,15 +985,15 @@ i915_error_object_create(struct drm_i915_private *i915,
if (ret)
goto unwind;
}
- goto out;

+ if (compress_flush(&compress, dst)) {
unwind:
- while (dst->page_count--)
- free_page((unsigned long)dst->pages[dst->page_count]);
- kfree(dst);
- dst = NULL;
+ 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;
--
2.19.0