From 3367aa7d74d240261de2543ddb35531ccad9d884 Mon Sep 17 00:00:00 2001 From: Javier Martinez Canillas Date: Wed, 11 May 2022 13:30:39 +0200 Subject: fbdev: Restart conflicting fb removal loop when unregistering devices Drivers that want to remove registered conflicting framebuffers prior to register their own framebuffer, call to remove_conflicting_framebuffers(). This function takes the registration_lock mutex, to prevent a race when drivers register framebuffer devices. But if a conflicting framebuffer device is found, the underlaying platform device is unregistered and this will lead to the platform driver .remove callback to be called. Which in turn will call to unregister_framebuffer() that takes the same lock. To prevent this, a struct fb_info.forced_out field was used as indication to unregister_framebuffer() whether the mutex has to be grabbed or not. But this could be unsafe, since the fbdev core is making assumptions about what drivers may or may not do in their .remove callbacks. Allowing to run these callbacks with the registration_lock held can cause deadlocks, since the fbdev core has no control over what drivers do in their removal path. A better solution is to drop the lock before platform_device_unregister(), so unregister_framebuffer() can take it when called from the fbdev driver. The lock is acquired again after the device has been unregistered and at this point the removal loop can be restarted. Since the conflicting framebuffer device has already been removed, the loop would just finish when no more conflicting framebuffers are found. Suggested-by: Daniel Vetter Signed-off-by: Javier Martinez Canillas Reviewed-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20220511113039.1252432-1-javierm@redhat.com --- include/linux/fb.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/fb.h b/include/linux/fb.h index 69c67c70fa78..bbe1e4571899 100644 --- a/include/linux/fb.h +++ b/include/linux/fb.h @@ -511,7 +511,6 @@ struct fb_info { } *apertures; bool skip_vt_switch; /* no VT switch on suspend/resume required */ - bool forced_out; /* set when being removed by another driver */ }; static inline struct apertures_struct *alloc_apertures(unsigned int max_num) { -- cgit v1.2.3 From 01357a5a45ed8eb9543183f5c9c6713ae60fc1f3 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Christian=20K=C3=B6nig?= Date: Sun, 24 Apr 2022 16:55:14 +0200 Subject: dma-buf: cleanup dma_fence_unwrap implementation MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Move the code from the inline functions into exported functions. Signed-off-by: Christian König Acked-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20220518135844.3338-3-christian.koenig@amd.com --- include/linux/dma-fence-unwrap.h | 52 ++++------------------------------------ 1 file changed, 4 insertions(+), 48 deletions(-) (limited to 'include/linux') diff --git a/include/linux/dma-fence-unwrap.h b/include/linux/dma-fence-unwrap.h index 77e335a1bcac..e7c219da4ed7 100644 --- a/include/linux/dma-fence-unwrap.h +++ b/include/linux/dma-fence-unwrap.h @@ -1,7 +1,5 @@ /* SPDX-License-Identifier: GPL-2.0-only */ /* - * fence-chain: chain fences together in a timeline - * * Copyright (C) 2022 Advanced Micro Devices, Inc. * Authors: * Christian König @@ -10,8 +8,7 @@ #ifndef __LINUX_DMA_FENCE_UNWRAP_H #define __LINUX_DMA_FENCE_UNWRAP_H -#include -#include +struct dma_fence; /** * struct dma_fence_unwrap - cursor into the container structure @@ -33,50 +30,9 @@ struct dma_fence_unwrap { unsigned int index; }; -/* Internal helper to start new array iteration, don't use directly */ -static inline struct dma_fence * -__dma_fence_unwrap_array(struct dma_fence_unwrap * cursor) -{ - cursor->array = dma_fence_chain_contained(cursor->chain); - cursor->index = 0; - return dma_fence_array_first(cursor->array); -} - -/** - * dma_fence_unwrap_first - return the first fence from fence containers - * @head: the entrypoint into the containers - * @cursor: current position inside the containers - * - * Unwraps potential dma_fence_chain/dma_fence_array containers and return the - * first fence. - */ -static inline struct dma_fence * -dma_fence_unwrap_first(struct dma_fence *head, struct dma_fence_unwrap *cursor) -{ - cursor->chain = dma_fence_get(head); - return __dma_fence_unwrap_array(cursor); -} - -/** - * dma_fence_unwrap_next - return the next fence from a fence containers - * @cursor: current position inside the containers - * - * Continue unwrapping the dma_fence_chain/dma_fence_array containers and return - * the next fence from them. - */ -static inline struct dma_fence * -dma_fence_unwrap_next(struct dma_fence_unwrap *cursor) -{ - struct dma_fence *tmp; - - ++cursor->index; - tmp = dma_fence_array_next(cursor->array, cursor->index); - if (tmp) - return tmp; - - cursor->chain = dma_fence_chain_walk(cursor->chain); - return __dma_fence_unwrap_array(cursor); -} +struct dma_fence *dma_fence_unwrap_first(struct dma_fence *head, + struct dma_fence_unwrap *cursor); +struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor); /** * dma_fence_unwrap_for_each - iterate over all fences in containers -- cgit v1.2.3 From 8f61973718485f3e89bc4f408f929048b7b47c83 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Christian=20K=C3=B6nig?= Date: Wed, 4 May 2022 13:01:29 +0200 Subject: dma-buf: return only unsignaled fences in dma_fence_unwrap_for_each v3 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit dma_fence_chain containers cleanup signaled fences automatically, so filter those out from arrays as well. v2: fix missing walk over the array v3: massively simplify the patch and actually update the description. Signed-off-by: Christian König Reviewed-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20220518135844.3338-4-christian.koenig@amd.com --- include/linux/dma-fence-unwrap.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/dma-fence-unwrap.h b/include/linux/dma-fence-unwrap.h index e7c219da4ed7..a4d342fef8e0 100644 --- a/include/linux/dma-fence-unwrap.h +++ b/include/linux/dma-fence-unwrap.h @@ -43,9 +43,13 @@ struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor); * Unwrap dma_fence_chain and dma_fence_array containers and deep dive into all * potential fences in them. If @head is just a normal fence only that one is * returned. + * + * Note that signalled fences are opportunistically filtered out, which + * means the iteration is potentially over no fence at all. */ #define dma_fence_unwrap_for_each(fence, cursor, head) \ for (fence = dma_fence_unwrap_first(head, cursor); fence; \ - fence = dma_fence_unwrap_next(cursor)) + fence = dma_fence_unwrap_next(cursor)) \ + if (!dma_fence_is_signaled(fence)) #endif -- cgit v1.2.3 From 245a4a7b531cffb41233a716497c25b06835cf4b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Christian=20K=C3=B6nig?= Date: Mon, 25 Apr 2022 14:22:12 +0200 Subject: dma-buf: generalize dma_fence unwrap & merging v3 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Introduce a dma_fence_unwrap_merge() macro which allows to unwrap fences which potentially can be containers as well and then merge them back together into a flat dma_fence_array. v2: rename the function, add some more comments about how the wrapper is used, move filtering of signaled fences into the unwrap iterator, add complex selftest which covers more cases. v3: fix signaled fence filtering once more Signed-off-by: Christian König Reviewed-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20220518135844.3338-5-christian.koenig@amd.com --- include/linux/dma-fence-unwrap.h | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) (limited to 'include/linux') diff --git a/include/linux/dma-fence-unwrap.h b/include/linux/dma-fence-unwrap.h index a4d342fef8e0..390de1ee9d35 100644 --- a/include/linux/dma-fence-unwrap.h +++ b/include/linux/dma-fence-unwrap.h @@ -52,4 +52,28 @@ struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor); fence = dma_fence_unwrap_next(cursor)) \ if (!dma_fence_is_signaled(fence)) +struct dma_fence *__dma_fence_unwrap_merge(unsigned int num_fences, + struct dma_fence **fences, + struct dma_fence_unwrap *cursors); + +/** + * dma_fence_unwrap_merge - unwrap and merge fences + * + * All fences given as parameters are unwrapped and merged back together as flat + * dma_fence_array. Useful if multiple containers need to be merged together. + * + * Implemented as a macro to allocate the necessary arrays on the stack and + * account the stack frame size to the caller. + * + * Returns NULL on memory allocation failure, a dma_fence object representing + * all the given fences otherwise. + */ +#define dma_fence_unwrap_merge(...) \ + ({ \ + struct dma_fence *__f[] = { __VA_ARGS__ }; \ + struct dma_fence_unwrap __c[ARRAY_SIZE(__f)]; \ + \ + __dma_fence_unwrap_merge(ARRAY_SIZE(__f), __f, __c); \ + }) + #endif -- cgit v1.2.3