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path: root/include/linux/dma-resv.h
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2022-04-07dma-buf: drop seq count based updateChristian König1-12/+0
This should be possible now since we don't have the distinction between exclusive and shared fences any more. The only possible pitfall is that a dma_fence would be reused during the RCU grace period, but even that could be handled with a single extra check. Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20220407085946.744568-15-christian.koenig@amd.com
2022-04-07dma-buf: add DMA_RESV_USAGE_BOOKKEEP v3Christian König1-1/+12
Add an usage for submissions independent of implicit sync but still interesting for memory management. v2: cleanup the kerneldoc a bit v3: separate amdgpu changes from this Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20220407085946.744568-10-christian.koenig@amd.com
2022-04-07dma-buf: add DMA_RESV_USAGE_KERNEL v3Christian König1-3/+21
Add an usage for kernel submissions. Waiting for those are mandatory for dynamic DMA-bufs. As a precaution this patch also changes all occurrences where fences are added as part of memory management in TTM, VMWGFX and i915 to use the new value because it now becomes possible for drivers to ignore fences with the WRITE usage. v2: use "must" in documentation, fix whitespaces v3: separate out some driver changes and better document why some changes should still be part of this patch. Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20220407085946.744568-5-christian.koenig@amd.com
2022-04-07dma-buf & drm/amdgpu: remove dma_resv workaroundChristian König1-36/+11
Rework the internals of the dma_resv object to allow adding more than one write fence and remember for each fence what purpose it had. This allows removing the workaround from amdgpu which used a container for this instead. Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: amd-gfx@lists.freedesktop.org Link: https://patchwork.freedesktop.org/patch/msgid/20220407085946.744568-4-christian.koenig@amd.com
2022-04-07dma-buf: specify usage while adding fences to dma_resv obj v7Christian König1-10/+15
Instead of distingting between shared and exclusive fences specify the fence usage while adding fences. Rework all drivers to use this interface instead and deprecate the old one. v2: some kerneldoc comments suggested by Daniel v3: fix a missing case in radeon v4: rebase on nouveau changes, fix lockdep and temporary disable warning v5: more documentation updates v6: separate internal dma_resv changes from this patch, avoids to disable warning temporary, rebase on upstream changes v7: fix missed case in lima driver, minimize changes to i915_gem_busy_ioctl Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20220407085946.744568-3-christian.koenig@amd.com
2022-04-07dma-buf: add enum dma_resv_usage v4Christian König1-13/+60
This change adds the dma_resv_usage enum and allows us to specify why a dma_resv object is queried for its containing fences. Additional to that a dma_resv_usage_rw() helper function is added to aid retrieving the fences for a read or write userspace submission. This is then deployed to the different query functions of the dma_resv object and all of their users. When the write paratermer was previously true we now use DMA_RESV_USAGE_WRITE and DMA_RESV_USAGE_READ otherwise. v2: add KERNEL/OTHER in separate patch v3: some kerneldoc suggestions by Daniel v4: some more kerneldoc suggestions by Daniel, fix missing cases lost in the rebase pointed out by Bas. Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20220407085946.744568-2-christian.koenig@amd.com
2022-04-06dma-buf/drivers: make reserving a shared slot mandatory v4Christian König1-2/+2
Audit all the users of dma_resv_add_excl_fence() and make sure they reserve a shared slot also when only trying to add an exclusive fence. This is the next step towards handling the exclusive fence like a shared one. v2: fix missed case in amdgpu v3: and two more radeon, rename function v4: add one more case to TTM, fix i915 after rebase Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20220406075132.3263-2-christian.koenig@amd.com
2022-04-05dma-buf: finally make dma_resv_excl_fence private v2Christian König1-17/+0
Drivers should never touch this directly. v2: fix rebase clash Signed-off-by: Christian König <christian.koenig@amd.com> Link: https://patchwork.freedesktop.org/patch/msgid/20220321135856.1331-10-christian.koenig@amd.com Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2022-04-03dma-buf: add dma_resv_get_singleton v2Christian König1-0/+2
Add a function to simplify getting a single fence for all the fences in the dma_resv object. v2: fix ref leak in error handling Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20220321135856.1331-3-christian.koenig@amd.com
2022-04-01dma-buf: drop the DAG approach for the dma_resv object v3Christian König1-17/+5
So far we had the approach of using a directed acyclic graph with the dma_resv obj. This turned out to have many downsides, especially it means that every single driver and user of this interface needs to be aware of this restriction when adding fences. If the rules for the DAG are not followed then we end up with potential hard to debug memory corruption, information leaks or even elephant big security holes because we allow userspace to access freed up memory. Since we already took a step back from that by always looking at all fences we now go a step further and stop dropping the shared fences when a new exclusive one is added. v2: Drop some now superflous documentation v3: Add some more documentation for the new handling. Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20220321135856.1331-11-christian.koenig@amd.com
2022-03-24dma-buf: finally make the dma_resv_list private v2Christian König1-25/+1
Drivers should never touch this directly. v2: drop kerneldoc for now internal handling Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20220321135856.1331-2-christian.koenig@amd.com
2022-03-24dma-buf: add dma_resv_replace_fences v2Christian König1-0/+2
This function allows to replace fences from the shared fence list when we can gurantee that the operation represented by the original fence has finished or no accesses to the resources protected by the dma_resv object any more when the new fence finishes. Then use this function in the amdkfd code when BOs are unmapped from the process. v2: add an example when this is usefull. Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20220321135856.1331-1-christian.koenig@amd.com
2022-01-31dma-resv: some doc polish for iteratorsDaniel Vetter1-1/+12
Hammer it a bit more in that iterators can be restarted and when that matters, plus suggest to prefer the locked version whenver. Also delete the two leftover kerneldoc for static functions plus sprinkle some more links while at it. v2: Keep some comments (Christian) 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: "Christian König" <christian.koenig@amd.com> Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org Link: https://patchwork.freedesktop.org/patch/msgid/20211130152756.1388106-1-daniel.vetter@ffwll.ch
2022-01-19dma-buf: drop excl_fence parameter from dma_resv_get_fencesChristian König1-2/+2
Returning the exclusive fence separately is no longer used. Instead add a write parameter to indicate the use case. Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20211207123411.167006-4-christian.koenig@amd.com
2021-11-17dma-buf: nuke dma_resv_get_excl_unlockedChristian König1-26/+0
Heureka, that's finally not used any more. Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20210917123513.1106-27-christian.koenig@amd.com
2021-11-11dma-buf: add dma_fence_describe and dma_resv_describe v2Christian König1-0/+1
Add functions to dump dma_fence and dma_resv objects into a seq_file and use them for printing the debugfs information. v2: fix missing include reported by test robot. Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Rob Clark <robdclark@gmail.com> Link: https://patchwork.freedesktop.org/patch/msgid/20211103081231.18578-2-christian.koenig@amd.com
2021-10-25Merge drm/drm-next into drm-misc-nextMaxime Ripard1-1/+1
drm-misc-next hasn't been updated in a while and I need a post -rc2 state to merge some vc4 patches. Signed-off-by: Maxime Ripard <maxime@cerno.tech>
2021-10-11dma-resv: Fix dma_resv_get_fences and dma_resv_copy_fences after conversionTvrtko Ursulin1-1/+4
Cache the count of shared fences in the iterator to avoid dereferencing the dma_resv_object outside the RCU protection. Otherwise iterator and its users can observe an incosistent state which makes it impossible to use safely. Such as: <6> [187.517041] [IGT] gem_sync: executing <7> [187.536343] i915 0000:00:02.0: [drm:i915_gem_context_create_ioctl [i915]] HW context 1 created <7> [187.536793] i915 0000:00:02.0: [drm:i915_gem_context_create_ioctl [i915]] HW context 1 created <6> [187.551235] [IGT] gem_sync: starting subtest basic-many-each <1> [188.935462] BUG: kernel NULL pointer dereference, address: 0000000000000010 <1> [188.935485] #PF: supervisor write access in kernel mode <1> [188.935495] #PF: error_code(0x0002) - not-present page <6> [188.935504] PGD 0 P4D 0 <4> [188.935512] Oops: 0002 [#1] PREEMPT SMP NOPTI <4> [188.935521] CPU: 2 PID: 1467 Comm: gem_sync Not tainted 5.15.0-rc4-CI-Patchwork_21264+ #1 <4> [188.935535] Hardware name: /NUC6CAYB, BIOS AYAPLCEL.86A.0049.2018.0508.1356 05/08/2018 <4> [188.935546] RIP: 0010:dma_resv_get_fences+0x116/0x2d0 <4> [188.935560] Code: 10 85 c0 7f c9 be 03 00 00 00 e8 15 8b df ff eb bd e8 8e c6 ff ff eb b6 41 8b 04 24 49 8b 55 00 48 89 e7 8d 48 01 41 89 0c 24 <4c> 89 34 c2 e8 41 f2 ff ff 49 89 c6 48 85 c0 75 8c 48 8b 44 24 10 <4> [188.935583] RSP: 0018:ffffc900011dbcc8 EFLAGS: 00010202 <4> [188.935593] RAX: 0000000000000000 RBX: 00000000ffffffff RCX: 0000000000000001 <4> [188.935603] RDX: 0000000000000010 RSI: ffffffff822e343c RDI: ffffc900011dbcc8 <4> [188.935613] RBP: ffffc900011dbd48 R08: ffff88812d255bb8 R09: 00000000fffffffe <4> [188.935623] R10: 0000000000000001 R11: 0000000000000000 R12: ffffc900011dbd44 <4> [188.935633] R13: ffffc900011dbd50 R14: ffff888113d29cc0 R15: 0000000000000000 <4> [188.935643] FS: 00007f68d17e9700(0000) GS:ffff888277900000(0000) knlGS:0000000000000000 <4> [188.935655] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 <4> [188.935665] CR2: 0000000000000010 CR3: 000000012d0a4000 CR4: 00000000003506e0 <4> [188.935676] Call Trace: <4> [188.935685] i915_gem_object_wait+0x1ff/0x410 [i915] <4> [188.935988] i915_gem_wait_ioctl+0xf2/0x2a0 [i915] <4> [188.936272] ? i915_gem_object_wait+0x410/0x410 [i915] <4> [188.936533] drm_ioctl_kernel+0xae/0x140 <4> [188.936546] drm_ioctl+0x201/0x3d0 <4> [188.936555] ? i915_gem_object_wait+0x410/0x410 [i915] <4> [188.936820] ? __fget_files+0xc2/0x1c0 <4> [188.936830] ? __fget_files+0xda/0x1c0 <4> [188.936839] __x64_sys_ioctl+0x6d/0xa0 <4> [188.936848] do_syscall_64+0x3a/0xb0 <4> [188.936859] entry_SYSCALL_64_after_hwframe+0x44/0xae If the shared object has changed during the RCU unlocked period callers will correctly handle the restart on the next iteration. Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Fixes: 96601e8a4755 ("dma-buf: use new iterator in dma_resv_copy_fences") Fixes: d3c80698c9f5 ("dma-buf: use new iterator in dma_resv_get_fences v3") Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/4274 Cc: Christian König <christian.koenig@amd.com> 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 Link: https://patchwork.freedesktop.org/patch/msgid/20211008095007.972693-1-tvrtko.ursulin@linux.intel.com Reviewed-by: Christian König <christian.koenig@amd.com> Signed-off-by: Christian König <christian.koenig@amd.com>
2021-10-11Merge tag 'drm-intel-gt-next-2021-10-08' of ↵Dave Airlie1-1/+1
git://anongit.freedesktop.org/drm/drm-intel into drm-next UAPI Changes: - Add uAPI for using PXP protected objects Mesa changes: https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8064 - Add PCI IDs and LMEM discovery/placement uAPI for DG1 Mesa changes: https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11584 - Disable engine bonding on Gen12+ except TGL, RKL and ADL-S Cross-subsystem Changes: - Merges 'tip/locking/wwmutex' branch (core kernel tip) - "mei: pxp: export pavp client to me client bus" Core Changes: - Update ttm_move_memcpy for async use (Thomas) Driver Changes: - Enable GuC submission by default on DG1 (Matt B) - Add PXP (Protected Xe Path) support for Gen12 integrated (Daniele, Sean, Anshuman) See "drm/i915/pxp: add PXP documentation" for details! - Remove force_probe protection for ADL-S (Raviteja) - Add base support for XeHP/XeHP SDV (Matt R, Stuart, Lucas) - Handle DRI_PRIME=1 on Intel igfx + Intel dgfx hybrid graphics setup (Tvrtko) - Use Transparent Hugepages when IOMMU is enabled (Tvrtko, Chris) - Implement LMEM backup and restore for suspend / resume (Thomas) - Report INSTDONE_GEOM values in error state for DG2 (Matt R) - Add DG2-specific shadow register table (Matt R) - Update Gen11/Gen12/XeHP shadow register tables (Matt R) - Maintain backward-compatible nested batch behavior on TGL+ (Matt R) - Add new LRI reg offsets for DG2 (Akeem) - Initialize unused MOCS entries to device specific values (Ayaz) - Track and use the correct UC MOCS index on Gen12 (Ayaz) - Add separate MOCS table for Gen12 devices other than TGL/RKL (Ayaz) - Simplify the locking and eliminate some RCU usage (Daniel) - Add some flushing for the 64K GTT path (Matt A) - Mark GPU wedging on driver unregister unrecoverable (Janusz) - Major rework in the GuC codebase, simplify locking and add docs (Matt B) - Add DG1 GuC/HuC firmwares (Daniele, Matt B) - Remember to call i915_sw_fence_fini on guc_state.blocked (Matt A) - Use "gt" forcewake domain name for error messages instead of "blitter" (Matt R) - Drop now duplicate LMEM uAPI RFC kerneldoc section (Daniel) - Fix early tracepoints for requests (Matt A) - Use locked access to ctx->engines in set_priority (Daniel) - Convert gen6/gen7/gen8 read operations to fwtable (Matt R) - Drop gen11/gen12 specific mmio write handlers (Matt R) - Drop gen11 specific mmio read handlers (Matt R) - Use designated initializers for init/exit table (Kees) - Fix syncmap memory leak (Matt B) - Add pretty printing for buddy allocator state debug (Matt A) - Fix potential error pointer dereference in pinned_context() (Dan) - Remove IS_ACTIVE macro (Lucas) - Static code checker fixes (Nathan) - Clean up disabled warnings (Nathan) - Increase timeout in i915_gem_contexts selftests 5x for GuC submission (Matt B) - Ensure wa_init_finish() is called for ctx workaround list (Matt R) - Initialize L3CC table in mocs init (Sreedhar, Ayaz, Ram) - Get PM ref before accessing HW register (Vinay) - Move __i915_gem_free_object to ttm_bo_destroy (Maarten) - Deduplicate frequency dump on debugfs (Lucas) - Make wa list per-gt (Venkata) - Do not define dummy vma in stack (Venkata) - Take pinning into account in __i915_gem_object_is_lmem (Matt B, Thomas) - Do not report currently active engine when describing objects (Tvrtko) - Fix pdfdocs build error by removing nested grid from GuC docs (Akira) - Remove false warning from the rps worker (Tejas) - Flush buffer pools on driver remove (Janusz) - Fix runtime pm handling in i915_gem_shrink (Maarten) - Rework TTM object initialization slightly (Thomas) - Use fixed offset for PTEs location (Michal Wa) - Verify result from CTB (de)register action and improve error messages (Michal Wa) - Fix bug in user proto-context creation that leaked contexts (Matt B) - Re-use Gen11 forcewake read functions on Gen12 (Matt R) - Make shadow tables range-based (Matt R) - Ditch the i915_gem_ww_ctx loop member (Thomas, Maarten) - Use NULL instead of 0 where appropriate (Ville) - Rename pci/debugfs functions to respect file prefix (Jani, Lucas) - Drop guc_communication_enabled (Daniele) - Selftest fixes (Thomas, Daniel, Matt A, Maarten) - Clean up inconsistent indenting (Colin) - Use direction definition DMA_BIDIRECTIONAL instead of PCI_DMA_BIDIRECTIONAL (Cai) - Add "intel_" as prefix in set_mocs_index() (Ayaz) From: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/YWAO80MB2eyToYoy@jlahtine-mobl.ger.corp.intel.com Signed-off-by: Dave Airlie <airlied@redhat.com>
2021-10-07dma-buf: add dma_resv_for_each_fence v3Christian König1-0/+20
A simpler version of the iterator to be used when the dma_resv object is locked. v2: fix index check here as well v3: minor coding improvement, some documentation cleanup Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20211006123609.2026-1-christian.koenig@amd.com
2021-10-06dma-buf: add dma_resv_for_each_fence_unlocked v8Christian König1-0/+95
Abstract the complexity of iterating over all the fences in a dma_resv object. The new loop handles the whole RCU and retry dance and returns only fences where we can be sure we grabbed the right one. v2: fix accessing the shared fences while they might be freed, improve kerneldoc, rename _cursor to _iter, add dma_resv_iter_is_exclusive, add dma_resv_iter_begin/end v3: restructor the code, move rcu_read_lock()/unlock() into the iterator, add dma_resv_iter_is_restarted() v4: fix NULL deref when no explicit fence exists, drop superflous rcu_read_lock()/unlock() calls. v5: fix typos in the documentation v6: fix coding error when excl fence is NULL v7: one more logic fix v8: fix index check in dma_resv_iter_is_exclusive() Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> (v7) Link: https://patchwork.freedesktop.org/patch/msgid/20211005113742.1101-2-christian.koenig@amd.com
2021-09-17kernel/locking: Add context to ww_mutex_trylock()Maarten Lankhorst1-1/+1
i915 will soon gain an eviction path that trylock a whole lot of locks for eviction, getting dmesg failures like below: BUG: MAX_LOCK_DEPTH too low! turning off the locking correctness validator. depth: 48 max: 48! 48 locks held by i915_selftest/5776: #0: ffff888101a79240 (&dev->mutex){....}-{3:3}, at: __driver_attach+0x88/0x160 #1: ffffc900009778c0 (reservation_ww_class_acquire){+.+.}-{0:0}, at: i915_vma_pin.constprop.63+0x39/0x1b0 [i915] #2: ffff88800cf74de8 (reservation_ww_class_mutex){+.+.}-{3:3}, at: i915_vma_pin.constprop.63+0x5f/0x1b0 [i915] #3: ffff88810c7f9e38 (&vm->mutex/1){+.+.}-{3:3}, at: i915_vma_pin_ww+0x1c4/0x9d0 [i915] #4: ffff88810bad5768 (reservation_ww_class_mutex){+.+.}-{3:3}, at: i915_gem_evict_something+0x110/0x860 [i915] #5: ffff88810bad60e8 (reservation_ww_class_mutex){+.+.}-{3:3}, at: i915_gem_evict_something+0x110/0x860 [i915] ... #46: ffff88811964d768 (reservation_ww_class_mutex){+.+.}-{3:3}, at: i915_gem_evict_something+0x110/0x860 [i915] #47: ffff88811964e0e8 (reservation_ww_class_mutex){+.+.}-{3:3}, at: i915_gem_evict_something+0x110/0x860 [i915] INFO: lockdep is turned off. Fixing eviction to nest into ww_class_acquire is a high priority, but it requires a rework of the entire driver, which can only be done one step at a time. As an intermediate solution, add an acquire context to ww_mutex_trylock, which allows us to do proper nesting annotations on the trylocks, making the above lockdep splat disappear. This is also useful in regulator_lock_nested, which may avoid dropping regulator_nesting_mutex in the uncontended path, so use it there. TTM may be another user for this, where we could lock a buffer in a fastpath with list locks held, without dropping all locks we hold. [peterz: rework actual ww_mutex_trylock() implementations] Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/YUBGPdDDjKlxAuXJ@hirez.programming.kicks-ass.net
2021-08-30dma-resv: Give the docs a do-overDaniel Vetter1-5/+99
Specifically document the new/clarified rules around how the shared fences do not have any ordering requirements against the exclusive fence. But also document all the things a bit better, given how central struct dma_resv to dynamic buffer management the docs have been very inadequat. - Lots more links to other pieces of the puzzle. Unfortunately ttm_buffer_object has no docs, so no links :-( - Explain/complain a bit about dma_resv_locking_ctx(). I still don't like that one, but fixing the ttm call chains is going to be horrible. Plus we want to plug in real slowpath locking when we do that anyway. - Main part of the patch is some actual docs for struct dma_resv. Overall I think we still have a lot of bad naming in this area (e.g. dma_resv.fence is singular, but contains the multiple shared fences), but I think that's more indicative of how the semantics and rules are just not great. Another thing that's real awkard is how chaining exclusive fences right now means direct dma_resv.exclusive_fence pointer access with an rcu_assign_pointer. Not so great either. v2: - Fix a pile of typos (Matt, Jason) - Hammer it in that breaking the rules leads to use-after-free issues around dma-buf sharing (Christian) Reviewed-by: Christian König <christian.koenig@amd.com> Cc: Jason Ekstrand <jason@jlekstrand.net> Cc: Matthew Auld <matthew.auld@intel.com> Reviewed-by: Matthew Auld <matthew.auld@intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: "Christian König" <christian.koenig@amd.com> Cc: linux-media@vger.kernel.org Cc: linaro-mm-sig@lists.linaro.org Link: https://patchwork.freedesktop.org/patch/msgid/20210805104705.862416-21-daniel.vetter@ffwll.ch
2021-06-29<linux/dma-resv.h>: correct a function name in kernel-docRandy Dunlap1-1/+1
Fix kernel-doc function name warning: ../include/linux/dma-resv.h:227: warning: expecting prototype for dma_resv_exclusive(). Prototype was for dma_resv_excl_fence() instead Fixes: 6edbd6abb783d ("dma-buf: rename and cleanup dma_resv_get_excl v3") Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Sumit Semwal <sumit.semwal@linaro.org> Cc: Christian König <christian.koenig@amd.com> Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20210628004012.6792-1-rdunlap@infradead.org
2021-06-06dma-buf: drop the _rcu postfix on function names v3Christian König1-12/+5
The functions can be called both in _rcu context as well as while holding the lock. v2: add some kerneldoc as suggested by Daniel v3: fix indentation Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Jason Ekstrand <jason@jlekstrand.net> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20210602111714.212426-7-christian.koenig@amd.com
2021-06-06dma-buf: rename dma_resv_get_excl_rcu to _unlockedChristian König1-2/+2
That describes much better what the function is doing here. Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Jason Ekstrand <jason@jlekstrand.net> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20210602111714.212426-6-christian.koenig@amd.com
2021-06-06dma-buf: rename and cleanup dma_resv_get_list v2Christian König1-14/+13
When the comment needs to state explicitly that this is doesn't get a reference to the object then the function is named rather badly. Rename the function and use it in even more places. v2: use dma_resv_shared_list as new name Signed-off-by: Christian König <christian.koenig@amd.com> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20210602111714.212426-5-christian.koenig@amd.com
2021-06-06dma-buf: rename and cleanup dma_resv_get_excl v3Christian König1-8/+6
When the comment needs to state explicitly that this doesn't get a reference to the object then the function is named rather badly. Rename the function and use rcu_dereference_check(), this way it can be used from both rcu as well as lock protected critical sections. v2: improve kerneldoc as suggested by Daniel v3: use dma_resv_excl_fence as function name Signed-off-by: Christian König <christian.koenig@amd.com> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Reviewed-by: Jason Ekstrand <jason@jlekstrand.net> Link: https://patchwork.freedesktop.org/patch/msgid/20210602111714.212426-4-christian.koenig@amd.com
2021-06-04dma-buf: cleanup dma-resv shared fence debugging a bit v2Christian König1-8/+7
Make that a function instead of inline. v2: improve the kerneldoc wording as suggested by Daniel Signed-off-by: Christian König <christian.koenig@amd.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20210602111714.212426-3-christian.koenig@amd.com
2020-07-29dma-buf: Use sequence counter with associated wound/wait mutexAhmed S. Darwish1-1/+1
A sequence counter write side critical section must be protected by some form of locking to serialize writers. If the serialization primitive is not disabling preemption implicitly, preemption has to be explicitly disabled before entering the sequence counter write side critical section. The dma-buf reservation subsystem uses plain sequence counters to manage updates to reservations. Writer serialization is accomplished through a wound/wait mutex. Acquiring a wound/wait mutex does not disable preemption, so this needs to be done manually before and after the write side critical section. Use the newly-added seqcount_ww_mutex_t instead: - It associates the ww_mutex with the sequence count, which enables lockdep to validate that the write side critical section is properly serialized. - It removes the need to explicitly add preempt_disable/enable() around the write side critical section because the write_begin/end() functions for this new data type automatically do this. If lockdep is disabled this ww_mutex lock association is compiled out and has neither storage size nor runtime overhead. Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://lkml.kernel.org/r/20200720155530.1173732-13-a.darwish@linutronix.de
2020-07-29dma-buf: Remove custom seqcount lockdep class keyAhmed S. Darwish1-2/+0
Commit 3c3b177a9369 ("reservation: add support for read-only access using rcu") introduced a sequence counter to manage updates to reservations. Back then, the reservation object initializer reservation_object_init() was always inlined. Having the sequence counter initialization inlined meant that each of the call sites would have a different lockdep class key, which would've broken lockdep's deadlock detection. The aforementioned commit thus introduced, and exported, a custom seqcount lockdep class key and name. The commit 8735f16803f00 ("dma-buf: cleanup reservation_object_init...") transformed the reservation object initializer to a normal non-inlined C function. seqcount_init(), which automatically defines the seqcount lockdep class key and must be called non-inlined, can now be safely used. Remove the seqcount custom lockdep class key, name, and export. Use seqcount_init() inside the dma reservation object initializer. Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://lkml.kernel.org/r/20200720155530.1173732-12-a.darwish@linutronix.de
2019-08-16dma-buf: Restore seqlock around dma_resv updatesChris Wilson1-65/+48
This reverts 67c97fb79a7f ("dma-buf: add reservation_object_fences helper") dd7a7d1ff2f1 ("drm/i915: use new reservation_object_fences helper") 0e1d8083bddb ("dma-buf: further relax reservation_object_add_shared_fence") 5d344f58da76 ("dma-buf: nuke reservation_object seq number") The scenario that defeats simply grabbing a set of shared/exclusive fences and using them blissfully under RCU is that any of those fences may be reallocated by a SLAB_TYPESAFE_BY_RCU fence slab cache. In this scenario, while keeping the rcu_read_lock we need to establish that no fence was changed in the dma_resv after a read (or full) memory barrier. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Acked-by: Christian König <christian.koenig@amd.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190814182401.25009-1-chris@chris-wilson.co.uk
2019-08-13dma-buf: rename reservation_object to dma_resvChristian König1-0/+312
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/
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