| Message ID | 1374780533-17771-1-git-send-email-kamal@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 0e01617..919cc5c 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -1882,6 +1882,10 @@ i915_gem_object_move_to_active(struct drm_i915_gem_object *obj, u32 seqno = intel_ring_get_seqno(ring); BUG_ON(ring == NULL); + if (obj->ring != ring && obj->last_write_seqno) { + /* Keep the seqno relative to the current ring */ + obj->last_write_seqno = seqno; + } obj->ring = ring; /* Add a reference if we're newly entering the active list. */
This is a note to let you know that I have just added a patch titled drm/i915: Fix write-read race with multiple rings to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue This patch is scheduled to be released in version 3.8.13.6. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.8.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From caf40bcc8f6751b723f0ec78e2f67beb771bfb68 Mon Sep 17 00:00:00 2001 From: Chris Wilson <chris@chris-wilson.co.uk> Date: Tue, 9 Jul 2013 09:22:39 +0100 Subject: drm/i915: Fix write-read race with multiple rings commit 02978ff57a5bdfbf703d2bc5a4d933a53ede3144 upstream. Daniel noticed a problem where is we wrote to an object with ring A in the middle of a very long running batch, then executed a quick batch on ring B before a batch that reads from the same object, its obj->ring would now point to ring B, but its last_write_seqno would be still relative to ring A. This would allow for the user to read from the object before the GPU had completed the write, as set_domain would only check that ring B had passed the last_write_seqno. To fix this simply (and inelegantly), we bump the last_write_seqno when switching rings so that the last_write_seqno is always relative to the current obj->ring. This fixes igt/tests/gem_write_read_ring_switch. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> [danvet: Add note about the newly created igt which exercises this bug.] Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/gpu/drm/i915/i915_gem.c | 4 ++++ 1 file changed, 4 insertions(+) -- 1.8.1.2