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2020-07-21dma-fence: prime lockdep annotationsDaniel Vetter1-0/+1
Two in one go: - it is allowed to call dma_fence_wait() while holding a dma_resv_lock(). This is fundamental to how eviction works with ttm, so required. - it is allowed to call dma_fence_wait() from memory reclaim contexts, specifically from shrinker callbacks (which i915 does), and from mmu notifier callbacks (which amdgpu does, and which i915 sometimes also does, and probably always should, but that's kinda a debate). Also for stuff like HMM we really need to be able to do this, or things get real dicey. Consequence is that any critical path necessary to get to a dma_fence_signal for a fence must never a) call dma_resv_lock nor b) allocate memory with GFP_KERNEL. Also by implication of dma_resv_lock(), no userspace faulting allowed. That's some supremely obnoxious limitations, which is why we need to sprinkle the right annotations to all relevant paths. The one big locking context we're leaving out here is mmu notifiers, added in commit 23b68395c7c78a764e8963fc15a7cfd318bf187f Author: Daniel Vetter <daniel.vetter@ffwll.ch> Date: Mon Aug 26 22:14:21 2019 +0200 mm/mmu_notifiers: add a lockdep map for invalidate_range_start/end that one covers a lot of other callsites, and it's also allowed to wait on dma-fences from mmu notifiers. But there's no ready-made functions exposed to prime this, so I've left it out for now. v2: Also track against mmu notifier context. v3: kerneldoc to spec the cross-driver contract. Note that currently i915 throws in a hard-coded 10s timeout on foreign fences (not sure why that was done, but it's there), which is why that rule is worded with SHOULD instead of MUST. Also some of the mmu_notifier/shrinker rules might surprise SoC drivers, I haven't fully audited them all. Which is infeasible anyway, we'll need to run them with lockdep and dma-fence annotations and see what goes boom. v4: A spelling fix from Mika v5: #ifdef for CONFIG_MMU_NOTIFIER. Reported by 0day. Unfortunately this means lockdep enforcement is slightly inconsistent, it won't spot GFP_NOIO and GFP_NOFS allocations in the wrong spot if CONFIG_MMU_NOTIFIER is disabled in the kernel config. Oh well. v5: Note that only drivers/gpu has a reasonable (or at least historical) excuse to use dma_fence_wait() from shrinker and mmu notifier callbacks. Everyone else should either have a better memory manager model, or better hardware. This reflects discussions with Jason Gunthorpe. Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Felix Kuehling <Felix.Kuehling@amd.com> Cc: kernel test robot <lkp@intel.com> Acked-by: Christian König <christian.koenig@amd.com> Acked-by: Dave Airlie <airlied@redhat.com> Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Reviewed-by: Thomas Hellström <thomas.hellstrom@intel.com> (v4) Cc: Mika Kuoppala <mika.kuoppala@intel.com> Cc: Thomas Hellstrom <thomas.hellstrom@intel.com> Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org Cc: linux-rdma@vger.kernel.org Cc: amd-gfx@lists.freedesktop.org Cc: intel-gfx@lists.freedesktop.org Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Christian König <christian.koenig@amd.com> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200707201229.472834-3-daniel.vetter@ffwll.ch
2020-07-21dma-fence: basic lockdep annotationsDaniel Vetter1-0/+12
Design is similar to the lockdep annotations for workers, but with some twists: - We use a read-lock for the execution/worker/completion side, so that this explicit annotation can be more liberally sprinkled around. With read locks lockdep isn't going to complain if the read-side isn't nested the same way under all circumstances, so ABBA deadlocks are ok. Which they are, since this is an annotation only. - We're using non-recursive lockdep read lock mode, since in recursive read lock mode lockdep does not catch read side hazards. And we _very_ much want read side hazards to be caught. For full details of this limitation see commit e91498589746065e3ae95d9a00b068e525eec34f Author: Peter Zijlstra <peterz@infradead.org> Date: Wed Aug 23 13:13:11 2017 +0200 locking/lockdep/selftests: Add mixed read-write ABBA tests - To allow nesting of the read-side explicit annotations we explicitly keep track of the nesting. lock_is_held() allows us to do that. - The wait-side annotation is a write lock, and entirely done within dma_fence_wait() for everyone by default. - To be able to freely annotate helper functions I want to make it ok to call dma_fence_begin/end_signalling from soft/hardirq context. First attempt was using the hardirq locking context for the write side in lockdep, but this forces all normal spinlocks nested within dma_fence_begin/end_signalling to be spinlocks. That bollocks. The approach now is to simple check in_atomic(), and for these cases entirely rely on the might_sleep() check in dma_fence_wait(). That will catch any wrong nesting against spinlocks from soft/hardirq contexts. The idea here is that every code path that's critical for eventually signalling a dma_fence should be annotated with dma_fence_begin/end_signalling. The annotation ideally starts right after a dma_fence is published (added to a dma_resv, exposed as a sync_file fd, attached to a drm_syncobj fd, or anything else that makes the dma_fence visible to other kernel threads), up to and including the dma_fence_wait(). Examples are irq handlers, the scheduler rt threads, the tail of execbuf (after the corresponding fences are visible), any workers that end up signalling dma_fences and really anything else. Not annotated should be code paths that only complete fences opportunistically as the gpu progresses, like e.g. shrinker/eviction code. The main class of deadlocks this is supposed to catch are: Thread A: mutex_lock(A); mutex_unlock(A); dma_fence_signal(); Thread B: mutex_lock(A); dma_fence_wait(); mutex_unlock(A); Thread B is blocked on A signalling the fence, but A never gets around to that because it cannot acquire the lock A. Note that dma_fence_wait() is allowed to be nested within dma_fence_begin/end_signalling sections. To allow this to happen the read lock needs to be upgraded to a write lock, which means that any other lock is acquired between the dma_fence_begin_signalling() call and the call to dma_fence_wait(), and still held, this will result in an immediate lockdep complaint. The only other option would be to not annotate such calls, defeating the point. Therefore these annotations cannot be sprinkled over the code entirely mindless to avoid false positives. Originally I hope that the cross-release lockdep extensions would alleviate the need for explicit annotations: https://lwn.net/Articles/709849/ But there's a few reasons why that's not an option: - It's not happening in upstream, since it got reverted due to too many false positives: commit e966eaeeb623f09975ef362c2866fae6f86844f9 Author: Ingo Molnar <mingo@kernel.org> Date: Tue Dec 12 12:31:16 2017 +0100 locking/lockdep: Remove the cross-release locking checks This code (CONFIG_LOCKDEP_CROSSRELEASE=y and CONFIG_LOCKDEP_COMPLETIONS=y), while it found a number of old bugs initially, was also causing too many false positives that caused people to disable lockdep - which is arguably a worse overall outcome. - cross-release uses the complete() call to annotate the end of critical sections, for dma_fence that would be dma_fence_signal(). But we do not want all dma_fence_signal() calls to be treated as critical, since many are opportunistic cleanup of gpu requests. If these get stuck there's still the main completion interrupt and workers who can unblock everyone. Automatically annotating all dma_fence_signal() calls would hence cause false positives. - cross-release had some educated guesses for when a critical section starts, like fresh syscall or fresh work callback. This would again cause false positives without explicit annotations, since for dma_fence the critical sections only starts when we publish a fence. - Furthermore there can be cases where a thread never does a dma_fence_signal, but is still critical for reaching completion of fences. One example would be a scheduler kthread which picks up jobs and pushes them into hardware, where the interrupt handler or another completion thread calls dma_fence_signal(). But if the scheduler thread hangs, then all the fences hang, hence we need to manually annotate it. cross-release aimed to solve this by chaining cross-release dependencies, but the dependency from scheduler thread to the completion interrupt handler goes through hw where cross-release code can't observe it. In short, without manual annotations and careful review of the start and end of critical sections, cross-relese dependency tracking doesn't work. We need explicit annotations. v2: handle soft/hardirq ctx better against write side and dont forget EXPORT_SYMBOL, drivers can't use this otherwise. v3: Kerneldoc. v4: Some spelling fixes from Mika v5: Amend commit message to explain in detail why cross-release isn't the solution. v6: Pull out misplaced .rst hunk. Acked-by: Christian König <christian.koenig@amd.com> Acked-by: Dave Airlie <airlied@redhat.com> Cc: Felix Kuehling <Felix.Kuehling@amd.com> Reviewed-by: Thomas Hellström <thomas.hellstrom@intel.com> Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Mika Kuoppala <mika.kuoppala@intel.com> Cc: Thomas Hellstrom <thomas.hellstrom@intel.com> Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org Cc: linux-rdma@vger.kernel.org Cc: amd-gfx@lists.freedesktop.org Cc: intel-gfx@lists.freedesktop.org Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Christian König <christian.koenig@amd.com> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200707201229.472834-2-daniel.vetter@ffwll.ch
2019-08-17dma-fence: Store the timestamp in the same union as the cb_listChris Wilson1-5/+19
The timestamp and the cb_list are mutually exclusive, the cb_list can only be added to prior to being signaled (and once signaled we drain), while the timestamp is only valid upon being signaled. Both the timestamp and the cb_list are only valid while the fence is alive, and as soon as no references are held can be replaced by the rcu_head. By reusing the union for the timestamp, we squeeze the base dma_fence struct to 64 bytes on x86-64. v2: Sort the union chronologically Suggested-by: Christian König <christian.koenig@amd.com> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Christian König <christian.koenig@amd.com> Acked-by: Christian König <christian.koenig@amd.com>. Link: https://patchwork.freedesktop.org/patch/msgid/20190817153022.5749-1-chris@chris-wilson.co.uk
2019-08-17dma-fence: Shrink size of struct dma_fenceChris Wilson1-3/+3
Rearrange the couple of 32-bit atomics hidden amongst the field of pointers that unnecessarily caused the compiler to insert some padding, shrinks the size of the base struct dma_fence from 80 to 72 bytes on x86-64. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Christian König <christian.koenig@amd.com> Reviewed-by: Christian König <christian.koenig@amd.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190817144736.7826-3-chris@chris-wilson.co.uk
2019-08-13dma-buf: rename reservation_object to dma_resvChristian König1-2/+2
Be more consistent with the naming of the other DMA-buf objects. Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Link: https://patchwork.freedesktop.org/patch/323401/
2019-08-10dma-buf: make dma_fence structure a bit smaller v2Christian König1-2/+8
We clear the callback list on kref_put so that by the time we release the fence it is unused. No one should be adding to the cb_list that they don't themselves hold a reference for. This small change is actually making the structure 16% smaller. v2: add the comment to the code as well. Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Link: https://patchwork.freedesktop.org/patch/322916/
2019-05-30treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174Thomas Gleixner1-9/+1
Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 655 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Richard Fontana <rfontana@redhat.com> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070034.575739538@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-04-16dma-buf: explicitely note that dma-fence-chains use 64bit seqnoChristian König1-6/+15
Instead of checking the upper values of the sequence number use an explicit field in the dma_fence_ops structure to note if a sequence should be 32bit or 64bit. Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com> Link: https://patchwork.freedesktop.org/patch/299655/
2018-12-07dma-buf: make fence sequence numbers 64 bit v2Christian König1-7/+15
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/
2018-12-03dma-buf: add dma_fence_get_stubChristian König1-0/+1
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/
2018-07-03dma-fence: Make ->wait callback optionalDaniel Vetter1-5/+8
Almost everyone uses dma_fence_default_wait. v2: Also remove the BUG_ON(!ops->wait) (Chris). Reviewed-by: Christian König <christian.koenig@amd.com> (v1) Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Chris Wilson <chris@chris-wilson.co.uk> 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/20180503142603.28513-5-daniel.vetter@ffwll.ch
2018-07-02dma-fence: Make ->enable_signaling optionalDaniel Vetter1-1/+2
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
2018-07-02dma-fence: remove fill_driver_data callbackDaniel Vetter1-13/+3
Noticed while I was typing docs. Entirely unused. v2: Remove reference in @timeline_value_str too. While at it clarify why timeline_value_str has a fence parameter - we don't have an explicit timeline structure unfortunately. Cc: Eric Anholt <eric@anholt.net> Reviewed-by: Eric Anholt <eric@anholt.net> Reviewed-by: Christian König <christian.koenig@amd.com> (v1) Cc: Christian König <christian.koenig@amd.com> (v1) Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20180503142603.28513-2-daniel.vetter@ffwll.ch
2018-05-03Revert ↵Daniel Vetter1-13/+19
190c462d5be19ba622a82f5fd0625087c870a1e6..bf3012ada1b2222e770de5c35c1bb16f73b3a01d" I shouldn't have pushed this, CI was right - I failed to remove the BUG_ON(!ops->wait); Reported-by: Chris Wilson <chris@chris-wilson.co.uk> Acked-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
2018-05-03dma-fence: Make ->wait callback optionalDaniel Vetter1-5/+8
Almost everyone uses dma_fence_default_wait. Reviewed-by: Christian König <christian.koenig@amd.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> 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/20180427061724.28497-6-daniel.vetter@ffwll.ch
2018-05-03dma-fence: Make ->enable_signaling optionalDaniel Vetter1-1/+2
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. 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 Reviewed-by: Christian König <christian.koenig@amd.com> Link: https://patchwork.freedesktop.org/patch/msgid/20180427061724.28497-4-daniel.vetter@ffwll.ch
2018-05-03dma-fence: remove fill_driver_data callbackDaniel Vetter1-13/+3
Noticed while I was typing docs. Entirely unused. v2: Remove reference in @timeline_value_str too. While at it clarify why timeline_value_str has a fence parameter - we don't have an explicit timeline structure unfortunately. Cc: Eric Anholt <eric@anholt.net> Reviewed-by: Christian König <christian.koenig@amd.com> (v1) Reviewed-by: Eric Anholt <eric@anholt.net> Cc: Christian König <christian.koenig@amd.com> (v1) Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20180502082359.30345-1-daniel.vetter@ffwll.ch
2018-05-02dma-fence: Some kerneldoc polish for dma-fence.hDaniel Vetter1-81/+155
- Switch to inline member docs for dma_fence_ops. - Mild polish all around. - hyperlink all the things! v2: - Remove the various [in] annotations, they seem really uncommon in kerneldoc and look funny. v3: Linebreak the "Returns" part of the @fill_driver_data kerneldoc (Eric). Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org Reviewed-by: Eric Anholt <eric@anholt.net> Reviewed-by: Christian König <christian.koenig@amd.com> Link: https://patchwork.freedesktop.org/patch/msgid/20180427061724.28497-2-daniel.vetter@ffwll.ch
2017-11-09dma-buf/fence: Sparse wants __rcu on the object itselfChris Wilson1-1/+1
In order to silence sparse in dma_fence_get_rcu_safe(), we need to mark the incoming fence object as being RCU protected and not the pointer to the object. Cc: Dave Airlie <airlied@redhat.com> Cc: Jason Ekstrand <jason@jlekstrand.net> Cc: linaro-mm-sig@lists.linaro.org Cc: linux-media@vger.kernel.org Cc: Alex Deucher <alexander.deucher@amd.com> Cc: Christian König <christian.koenig@amd.com> Cc: Sumit Semwal <sumit.semwal@linaro.org> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Link: https://patchwork.freedesktop.org/patch/msgid/20171102200336.23347-3-ville.syrjala@linux.intel.com Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Acked-by: Christian König <christian.koenig@amd.com> Acked-by: Sumit Semwal <sumit.semwal@linaro.org> [vsyrjala: s/silent/silence/ in commit message] Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
2017-10-18dma-fence: remove duplicate word in commentFrank Binns1-1/+1
Signed-off-by: Frank Binns <frank.binns@imgtec.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/1508333423-5394-1-git-send-email-frank.binns@imgtec.com
2017-10-09dma-fence: fix dma_fence_get_rcu_safe v2Christian König1-1/+4
When dma_fence_get_rcu() fails to acquire a reference it doesn't necessary mean that there is no fence at all. It usually mean that the fence was replaced by a new one and in this situation we certainly want to have the new one as result and *NOT* NULL. v2: Keep extra check after dma_fence_get_rcu(). Signed-off-by: Christian König <christian.koenig@amd.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com> Link: https://patchwork.freedesktop.org/patch/msgid/1505469187-3565-1-git-send-email-deathsimple@vodafone.de
2017-07-27Backmerge tag 'v4.13-rc2' into drm-nextDave Airlie1-0/+2
Linux 4.13-rc2 This is required for drm-misc fixing.
2017-07-26dma-fence: Don't BUG_ON when not absolutely neededDaniel Vetter1-2/+2
It makes debugging a massive pain. 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 Reviewed-by: Lucas Stach <l.stach@pengutronix.de> Acked-by: Sumit Semwal <sumit.semwal@linaro.org> Acked-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20170720125107.26693-1-daniel.vetter@ffwll.ch Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2017-07-14dma-buf/fence: Avoid use of uninitialised timestampChris Wilson1-0/+2
[ 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
2017-06-30dma-buf/dma-fence: Extract __dma_fence_is_later()Chris Wilson1-1/+14
Often we have the task of comparing two seqno known to be on the same context, so provide a common __dma_fence_is_later(). Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: Sean Paul <seanpaul@chromium.org> Cc: Gustavo Padovan <gustavo@padovan.org> Reviewed-by: Sean Paul <seanpaul@chromium.org> Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com> Link: http://patchwork.freedesktop.org/patch/msgid/20170629125930.821-1-chris@chris-wilson.co.uk
2017-04-18mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCUPaul E. McKenney1-2/+2
A group of Linux kernel hackers reported chasing a bug that resulted from their assumption that SLAB_DESTROY_BY_RCU provided an existence guarantee, that is, that no block from such a slab would be reallocated during an RCU read-side critical section. Of course, that is not the case. Instead, SLAB_DESTROY_BY_RCU only prevents freeing of an entire slab of blocks. However, there is a phrase for this, namely "type safety". This commit therefore renames SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU in order to avoid future instances of this sort of confusion. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: <linux-mm@kvack.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> [ paulmck: Add comments mentioning the old name, as requested by Eric Dumazet, in order to help people familiar with the old name find the new one. ] Acked-by: David Rientjes <rientjes@google.com>
2017-01-09dma-fence: Introduce drm_fence_set_error() helperChris Wilson1-5/+25
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
2017-01-09dma-fence: Wrap querying the fence->statusChris Wilson1-0/+24
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
2016-11-15doc/dma-buf: Fix up include directivesDaniel Vetter1-1/+1
Would be great if everony could add $ make DOCBOOKS="" htmldocs to their build scripts to catch these. 0day should also report them, not sure why it failed to spot this. Fixes: f54d1867005c ("dma-buf: Rename struct fence to dma_fence") Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Gustavo Padovan <gustavo.padovan@collabora.co.uk> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: Christian König <christian.koenig@amd.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20161114115825.22050-4-daniel.vetter@ffwll.ch
2016-11-08dma-buf: return index of the first signaled fence (v2)monk.liu1-1/+2
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
2016-10-25dma-buf: Rename struct fence to dma_fenceChris Wilson1-0/+437
I plan to usurp the short name of struct fence for a core kernel struct, and so I need to rename the specialised fence/timeline for DMA operations to make room. A consensus was reached in https://lists.freedesktop.org/archives/dri-devel/2016-July/113083.html that making clear this fence applies to DMA operations was a good thing. Since then the patch has grown a bit as usage increases, so hopefully it remains a good thing! (v2...: rebase, rerun spatch) v3: Compile on msm, spotted a manual fixup that I broke. v4: Try again for msm, sorry Daniel coccinelle script: @@ @@ - struct fence + struct dma_fence @@ @@ - struct fence_ops + struct dma_fence_ops @@ @@ - struct fence_cb + struct dma_fence_cb @@ @@ - struct fence_array + struct dma_fence_array @@ @@ - enum fence_flag_bits + enum dma_fence_flag_bits @@ @@ ( - fence_init + dma_fence_init | - fence_release + dma_fence_release | - fence_free + dma_fence_free | - fence_get + dma_fence_get | - fence_get_rcu + dma_fence_get_rcu | - fence_put + dma_fence_put | - fence_signal + dma_fence_signal | - fence_signal_locked + dma_fence_signal_locked | - fence_default_wait + dma_fence_default_wait | - fence_add_callback + dma_fence_add_callback | - fence_remove_callback + dma_fence_remove_callback | - fence_enable_sw_signaling + dma_fence_enable_sw_signaling | - fence_is_signaled_locked + dma_fence_is_signaled_locked | - fence_is_signaled + dma_fence_is_signaled | - fence_is_later + dma_fence_is_later | - fence_later + dma_fence_later | - fence_wait_timeout + dma_fence_wait_timeout | - fence_wait_any_timeout + dma_fence_wait_any_timeout | - fence_wait + dma_fence_wait | - fence_context_alloc + dma_fence_context_alloc | - fence_array_create + dma_fence_array_create | - to_fence_array + to_dma_fence_array | - fence_is_array + dma_fence_is_array | - trace_fence_emit + trace_dma_fence_emit | - FENCE_TRACE + DMA_FENCE_TRACE | - FENCE_WARN + DMA_FENCE_WARN | - FENCE_ERR + DMA_FENCE_ERR ) ( ... ) Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk> Acked-by: Sumit Semwal <sumit.semwal@linaro.org> Acked-by: Christian König <christian.koenig@amd.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: http://patchwork.freedesktop.org/patch/msgid/20161025120045.28839-1-chris@chris-wilson.co.uk