54 lines
1.7 KiB
Diff
54 lines
1.7 KiB
Diff
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From fc6c6a4dde53bf68c519c0079b5957a24b7bad2b Mon Sep 17 00:00:00 2001
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From: Frediano Ziglio <fziglio@redhat.com>
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Date: Thu, 24 Sep 2015 14:25:14 +0100
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Subject: [PATCH 1/2] drm/qxl: avoid buffer reservation in qxl_crtc_page_flip
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This avoid a dependency lock error.
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According to https://lwn.net/Articles/548909/ users of WW mutex API
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should avoid using different context.
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When a buffer is reserved with qxl_bo_reserve a ww_mutex_lock without
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context is used. However during qxl_draw_dirty_fb different locks
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with specific context are used.
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This is detected during a machine booting with a debug kernel with lock
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dependency checking enabled.
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Like many other function in this file to avoid this problem object
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pinning is used. Once the object is pinned is not necessary to keep
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the lock so it can be released avoiding the locking problem.
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Signed-off-by: Frediano Ziglio <fziglio@redhat.com>
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---
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drivers/gpu/drm/qxl/qxl_display.c | 10 +++++++++-
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1 file changed, 9 insertions(+), 1 deletion(-)
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diff --git a/drivers/gpu/drm/qxl/qxl_display.c b/drivers/gpu/drm/qxl/qxl_display.c
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index 4649bd2ed340..183aea1abebc 100644
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--- a/drivers/gpu/drm/qxl/qxl_display.c
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+++ b/drivers/gpu/drm/qxl/qxl_display.c
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@@ -244,6 +244,10 @@ static int qxl_crtc_page_flip(struct drm_crtc *crtc,
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ret = qxl_bo_reserve(bo, false);
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if (ret)
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return ret;
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+ ret = qxl_bo_pin(bo, bo->type, NULL);
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+ qxl_bo_unreserve(bo);
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+ if (ret)
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+ return ret;
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qxl_draw_dirty_fb(qdev, qfb_src, bo, 0, 0,
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&norect, one_clip_rect, inc);
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@@ -257,7 +261,11 @@ static int qxl_crtc_page_flip(struct drm_crtc *crtc,
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}
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drm_vblank_put(dev, qcrtc->index);
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- qxl_bo_unreserve(bo);
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+ ret = qxl_bo_reserve(bo, false);
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+ if (!ret) {
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+ qxl_bo_unpin(bo);
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+ qxl_bo_unreserve(bo);
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+ }
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return 0;
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}
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--
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2.4.3
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