drm/i915: Break up error capture compression loops with cond_resched()

As the error capture will compress user buffers as directed to by the
user, it can take an arbitrary amount of time and space. Break up the
compression loops with a call to cond_resched(), that will allow other
processes to schedule (avoiding the soft lockups) and also serve as a
warning should we try to make this loop atomic in the future.

Testcase: igt/gem_exec_capture/many-*
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: stable@vger.kernel.org
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200916090059.3189-2-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index 6a3a2ce..6551ff0 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -311,6 +311,8 @@ static int compress_page(struct i915_vma_compress *c,
 
                if (zlib_deflate(zstream, Z_NO_FLUSH) != Z_OK)
                        return -EIO;
+
+               cond_resched();
        } while (zstream->avail_in);
 
        /* Fallback to uncompressed if we increase size? */
@@ -397,6 +399,7 @@ static int compress_page(struct i915_vma_compress *c,
        if (!(wc && i915_memcpy_from_wc(ptr, src, PAGE_SIZE)))
                memcpy(ptr, src, PAGE_SIZE);
        dst->pages[dst->page_count++] = ptr;
+       cond_resched();
 
        return 0;
 }