Currently there is an underlying assumption that i915_request_unsubmit()
is synchronous wrt the GPU -- that is the request is no longer in flight
as we remove it. In the near future that may change, and this may upset
our signaling as we can process an interrupt for that request while it
is no longer in flight.
CPU0 CPU1
intel_engine_breadcrumbs_irq
(queue request completion)
i915_request_cancel_signaling
... ...
i915_request_enable_signaling
dma_fence_signal
Hence in the time it took us to drop the lock to signal the request, a
preemption event may have occurred and re-queued the request. In the
process, that request would have seen I915_FENCE_FLAG_SIGNAL clear and
so reused the rq->signal_link that was in use on CPU0, leading to bad
pointer chasing in intel_engine_breadcrumbs_irq.
A related issue was that if someone started listening for a signal on a
completed but no longer in-flight request, we missed the opportunity to
immediately signal that request.
Furthermore, as intel_contexts may be immediately released during
request retirement, in order to be entirely sure that
intel_engine_breadcrumbs_irq may no longer dereference the intel_context
(ce->signals and ce->signal_link), we must wait for irq spinlock.
In order to prevent the race, we use a bit in the fence.flags to signal
the transfer onto the signal list inside intel_engine_breadcrumbs_irq.
For simplicity, we use the DMA_FENCE_FLAG_SIGNALED_BIT as it then
quickly signals to any outside observer that the fence is indeed signaled.
v2: Sketch out potential dma-fence API for manual signaling
v3: And the test_and_set_bit()
Fixes: 52c0fdb25c ("drm/i915: Replace global breadcrumbs with per-context interrupt tracking")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190508112452.18942-1-chris@chris-wilson.co.uk
(cherry picked from commit 0152b3b3f4)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
For a lot of use cases we need 64bit sequence numbers. Currently drivers
overload the dma_fence structure to store the additional bits.
Stop doing that and make the sequence number in the dma_fence always
64bit.
For compatibility with hardware which can do only 32bit sequences the
comparisons in __dma_fence_is_later only takes the lower 32bits as significant
when the upper 32bits are all zero.
v2: change the logic in __dma_fence_is_later
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Link: https://patchwork.freedesktop.org/patch/266927/
Extract of useful code from the timeline work. This provides a function
to return a stub or dummy fence which is always signaled.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Link: https://patchwork.freedesktop.org/patch/265248/
When this was introduced in
commit a519435a96
Author: Christian König <christian.koenig@amd.com>
Date: Tue Oct 20 16:34:16 2015 +0200
dma-buf/fence: add fence_wait_any_timeout function v2
there was a restriction added that this only works if the dma-fence
uses the dma_fence_default_wait hook. Which works for amdgpu, which is
the only caller. Well, until you share some buffers with e.g. i915,
then you get an -EINVAL.
But there's really no reason for this, because all drivers must
support callbacks. The special ->wait hook is only as an optimization;
if the driver needs to create a worker thread for an active callback,
then it can avoid to do that if it knows that there's a process
context available already. So ->wait is just an optimization, just
using the logic in dma_fence_default_wait() should work for all
drivers.
Let's remove this restriction.
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180503142603.28513-4-daniel.vetter@ffwll.ch
Many drivers have a trivial implementation for ->enable_signaling.
Let's make it optional by assuming that signalling is already
available when the callback isn't present.
v2: Don't do the trick to set the ENABLE_SIGNAL_BIT
unconditionally, it results in an expensive spinlock take for
everyone. Instead just check if the callback is present. Suggested by
Maarten.
Also move misplaced kerneldoc hunk to the right patch.
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com> (v1)
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Link: https://patchwork.freedesktop.org/patch/msgid/20180504141034.27727-1-daniel.vetter@ffwll.ch
In dma_fence_release() there is a WARN_ON which could be triggered by
several cases of wrong dma-fence usage. This patch adds a comment to
explain two use-cases to help driver developers that use dma-fence
and trigger that WARN_ON to better understand the reasons for it.
v2: change to a more generic, one-liner comment
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>
Commit e941759c74 ("fence: dma-buf cross-device synchronization") added
trace event fence_annotate_wait_on, but never used it. It was renamed
to dma_fence_annotate_wait_on by commit f54d186700 ("dma-buf: Rename
struct fence to dma_fence") but still not used. As defined trace events
have data structures and functions created for them, it is a waste of
memory if they are not used. Remove the unused trace event.
Link: http://lkml.kernel.org/r/20171013100625.6c820059@gandalf.local.home
Reviewed-by: Christian König <christian.koenig@amd.com>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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Backmerge tag 'v4.13-rc2' into drm-next
Linux 4.13-rc2
This is required for drm-misc fixing.
Pick up
1ed134e652 drm/vc4: Fix VBLANK handling in crtc->enable() path
From drm-misc-next-fixes, it was applied after the last pull request
was sent from that branch. We'll send it through drm-fixes instead.
[ 236.821534] WARNING: kmemcheck: Caught 64-bit read from uninitialized memory (ffff8802538683d0)
[ 236.828642] 420000001e7f0000000000000000000000080000000000000000000000000000
[ 236.839543] i i i i u u u u i i i i i i i i u u u u u u u u u u u u u u u u
[ 236.850420] ^
[ 236.854123] RIP: 0010:[<ffffffff81396f07>] [<ffffffff81396f07>] fence_signal+0x17/0xd0
[ 236.861313] RSP: 0018:ffff88024acd7ba0 EFLAGS: 00010282
[ 236.865027] RAX: ffffffff812f6a90 RBX: ffff8802527ca800 RCX: ffff880252cb30e0
[ 236.868801] RDX: ffff88024ac5d918 RSI: ffff880252f780e0 RDI: ffff880253868380
[ 236.872579] RBP: ffff88024acd7bc0 R08: ffff88024acd7be0 R09: 0000000000000000
[ 236.876407] R10: 0000000000000000 R11: 0000000000000000 R12: ffff880253868380
[ 236.880185] R13: ffff8802538684d0 R14: ffff880253868380 R15: ffff88024cd48e00
[ 236.883983] FS: 00007f1646d1a740(0000) GS:ffff88025d000000(0000) knlGS:0000000000000000
[ 236.890959] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 236.894702] CR2: ffff880251360318 CR3: 000000024ad21000 CR4: 00000000001406f0
[ 236.898481] [<ffffffff8130d1ad>] i915_gem_request_retire+0x1cd/0x230
[ 236.902439] [<ffffffff8130e2b3>] i915_gem_request_alloc+0xa3/0x2f0
[ 236.906435] [<ffffffff812fb1bd>] i915_gem_do_execbuffer.isra.41+0xb6d/0x18b0
[ 236.910434] [<ffffffff812fc265>] i915_gem_execbuffer2+0x95/0x1e0
[ 236.914390] [<ffffffff812ad625>] drm_ioctl+0x1e5/0x460
[ 236.918275] [<ffffffff8110d4cf>] do_vfs_ioctl+0x8f/0x5c0
[ 236.922168] [<ffffffff8110da3c>] SyS_ioctl+0x3c/0x70
[ 236.926090] [<ffffffff814b7a5f>] entry_SYSCALL_64_fastpath+0x17/0x93
[ 236.930045] [<ffffffffffffffff>] 0xffffffffffffffff
We only set the timestamp before we mark the fence as signaled. It is
done before to avoid observers having a window in which they may see the
fence as complete but no timestamp. Having it does incur a potential for
the timestamp to be written twice, and even for it to be corrupted if
the u64 write is not atomic. Instead use a new bit to record the
presence of the timestamp, and teach the readers to wait until it is set
if the fence is complete. There still remains a race where the timestamp
for the signaled fence may be shown before the fence is reported as
signaled, but that's a pre-existing error.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Reported-by: Rafael Antognolli <rafael.antognolli@intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170214124001.1930-1-chris@chris-wilson.co.uk
When a timeout of zero is specified, the caller is only interested in
the fence status.
In the current implementation, dma_fence_default_wait will always call
schedule_timeout() at least once for an unsignaled fence. This adds a
significant overhead to a fence status query.
Avoid this overhead by returning early if a zero timeout is specified.
v2: move early return after enable_signaling
Signed-off-by: Andres Rodriguez <andresx7@gmail.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170426144620.3560-1-andresx7@gmail.com
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Merge tag 'doc-4.11-images' of git://git.lwn.net/linux into drm-misc-next
Pointer for Markus's image conversion work.
We need this so we can merge all the pretty drm graphs for 4.12.
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
First slice of drm-misc-next for 4.12:
Core/subsystem-wide:
- link status core patch from Manasi, for signalling link train fail
to userspace. I also had the i915 patch in here, but that had a
small buglet in our CI, so reverted.
- more debugfs_remove removal from Noralf, almost there now (Noralf
said he'll try to follow up with the stragglers).
- drm todo moved into kerneldoc, for better visibility (see
Documentation/gpu/todo.rst), lots of starter tasks in there.
- devm_ of helpers + use it in sti (from Ben Gaignard, acked by Rob
Herring)
- extended framebuffer fbdev support (for fbdev flipping), and vblank
wait ioctl fbdev support (Maxime Ripard)
- misc small things all over, as usual
- add vblank callbacks to drm_crtc_funcs, plus make lots of good use
of this to simplify drivers (Shawn Guo)
- new atomic iterator macros to unconfuse old vs. new state
Small drivers:
- vc4 improvements from Eric
- vc4 kerneldocs (Eric)!
- tons of improvements for dw-mipi-dsi in rockchip from John Keeping
and Chris Zhong.
- MAINTAINERS entries for drivers managed in drm-misc. It's not yet
official, still an experiment, but definitely not complete fail and
better to avoid confusion. We kinda screwed that up with drm-misc a
bit when we started committers last year.
- qxl atomic conversion (Gabriel Krisman)
- bunch of virtual driver polish (qxl, virgl, ...)
- misc tiny patches all over
This is the first time we've done the same merge-window blackout for
drm-misc as we've done for drm-intel for ages, hence why we have a
_lot_ of stuff queued already. But it's still only half of drm-intel
(room to grow!), and the drivers in drm-misc experiment seems to work
at least insofar as that you also get lots of driver updates here
alredy.
* tag 'drm-misc-next-2017-03-06' of git://anongit.freedesktop.org/git/drm-misc: (141 commits)
drm/vc4: Fix OOPSes from trying to cache a partially constructed BO.
drm/vc4: Fulfill user BO creation requests from the kernel BO cache.
Revert "drm/i915: Implement Link Rate fallback on Link training failure"
drm/fb-helper: implement ioctl FBIO_WAITFORVSYNC
drm: Update drm_fbdev_cma_init documentation
drm/rockchip/dsi: add dw-mipi power domain support
drm/rockchip/dsi: fix insufficient bandwidth of some panel
dt-bindings: add power domain node for dw-mipi-rockchip
drm/rockchip/dsi: remove mode_valid function
drm/rockchip/dsi: dw-mipi: correct the coding style
drm/rockchip/dsi: dw-mipi: support RK3399 mipi dsi
dt-bindings: add rk3399 support for dw-mipi-rockchip
drm/rockchip: dw-mipi-dsi: add reset control
drm/rockchip: dw-mipi-dsi: support non-burst modes
drm/rockchip: dw-mipi-dsi: defer probe if panel is not loaded
drm/rockchip: vop: test for P{H,V}SYNC
drm/rockchip: dw-mipi-dsi: use positive check for N{H, V}SYNC
drm/rockchip: dw-mipi-dsi: use specific poll helper
drm/rockchip: dw-mipi-dsi: improve PLL configuration
drm/rockchip: dw-mipi-dsi: properly configure PHY timing
...
Fix up affected files that include this signal functionality via sched.h.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently this tracepoint is solely used by dma_fence_enable_sw_signaling,
however I have a need to manually perform the hw enabling of the
signaling and would like to emit this tracepoint for completeness.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170124115758.31353-1-chris@chris-wilson.co.uk
The dma_fence.error field (formerly known as dma_fence.status) is an
optional field that may be set by drivers before calling
dma_fence_signal(). The field can be used to indicate that the fence was
completed in err rather than with success, and is visible to other
consumers of the fence and to userspace via sync_file.
This patch renames the field from status to error so that its meaning is
hopefully more clear (and distinct from dma_fence_get_status() which is
a composite between the error state and signal state) and adds a helper
that validates the preconditions of when it is suitable to adjust the
error field.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20170104141222.6992-3-chris@chris-wilson.co.uk
The fence->status is an optional field that is only valid once the fence
has been signaled. (Driver may fill the fence->status with an error code
prior to calling dma_fence_signal().) Given the restriction upon its
validity, wrap querying of the fence->status into a helper
dma_fence_get_status().
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20170104141222.6992-2-chris@chris-wilson.co.uk
As the fence->status is an optional field that may be set before
dma_fence_signal() is called to convey that the fence completed with an
error, we have to ensure that it is always set to zero on initialisation
so that the typical use (i.e. unset) always flags a successful completion.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20170104141222.6992-1-chris@chris-wilson.co.uk
Reverts commit 847b19a39e
("dma-buf/fence: don't wait when specified timeout is zero")
When we don't call the wait function software signaling might never be
activated. This can cause infinite polling loops with unreliable interrupt
driven hardware.
v2: rebase on drm-next
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
[sumits: reword commit msg for checkpatch warnings]
Link: http://patchwork.freedesktop.org/patch/msgid/1478553376-18575-2-git-send-email-alexander.deucher@amd.com
Kernel functions taking a timeout usually return 1 on success even
when they get a zero timeout.
v2: agd: rebase on drm-next
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1478553376-18575-1-git-send-email-alexander.deucher@amd.com
Return the index of the first signaled fence. This information
is useful in some APIs like Vulkan.
v2: rebase on drm-next (fence -> dma_fence)
Signed-off-by: monk.liu <monk.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
[sumits: fix warnings]
Link: http://patchwork.freedesktop.org/patch/msgid/1478290570-30982-1-git-send-email-alexander.deucher@amd.com
Chris Wilson