drm/i915: Handle incomplete Z_FINISH for compressed error states

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>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181003082422.23214-1-chris@chris-wilson.co.uk
(cherry picked from commit 83bc0f5b432f60394466deef16fc753e27371d0b)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

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 f7f2aa71d8d9..a262a64f5625 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];