Linaro-mm-sig

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2541 discussions

[PATCH] dma-buf: Remove requirement for ops->map() from dma_buf_export

by Chris Wilson

Since commit 9ea0dfbf972 ("dma-buf: make map_atomic and map function pointers optional"), the core provides the no-op functions when map and map_atomic are not provided, so we no longer need assert that are supplied by a dma-buf exporter. Fixes: 09ea0dfbf972 ("dma-buf: make map_atomic and map function pointers optional") Signed-off-by: Chris Wilson <chris(a)chris-wilson.co.uk> Cc: Daniel Vetter <daniel(a)ffwll.ch> Cc: Gerd Hoffmann <kraxel(a)redhat.com> Cc: Sumit Semwal <sumit.semwal(a)linaro.org> --- drivers/dma-buf/dma-buf.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 13884474d158..02f7f9a89979 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -405,7 +405,6 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info) || !exp_info->ops->map_dma_buf || !exp_info->ops->unmap_dma_buf || !exp_info->ops->release - || !exp_info->ops->map || !exp_info->ops->mmap)) { return ERR_PTR(-EINVAL); } -- 2.18.0

6 years, 5 months

[PATCH] dma-buf: fix sanity check in dma_buf_export

by Gerd Hoffmann

Commit 09ea0dfbf972 made map_atomic and map function pointers optional, but didn't adapt the sanity check in dma_buf_export. Fix that. Note that the atomic map interface has been removed altogether meanwhile (commit f664a52695), therefore we have to remove the map check only. Signed-off-by: Gerd Hoffmann <kraxel(a)redhat.com> --- drivers/dma-buf/dma-buf.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 13884474d1..02f7f9a899 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -405,7 +405,6 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info) || !exp_info->ops->map_dma_buf || !exp_info->ops->unmap_dma_buf || !exp_info->ops->release - || !exp_info->ops->map || !exp_info->ops->mmap)) { return ERR_PTR(-EINVAL); } -- 2.9.3

6 years, 5 months

[PATCH 1/2] mm/cma: remove unsupported gfp_mask parameter from cma_alloc()

by Marek Szyprowski

cma_alloc() function doesn't really support gfp flags other than __GFP_NOWARN, so convert gfp_mask parameter to boolean no_warn parameter. This will help to avoid giving false feeling that this function supports standard gfp flags and callers can pass __GFP_ZERO to get zeroed buffer, what has already been an issue: see commit dd65a941f6ba ("arm64: dma-mapping: clear buffers allocated with FORCE_CONTIGUOUS flag"). Signed-off-by: Marek Szyprowski <m.szyprowski(a)samsung.com> --- arch/powerpc/kvm/book3s_hv_builtin.c | 2 +- drivers/s390/char/vmcp.c | 2 +- drivers/staging/android/ion/ion_cma_heap.c | 2 +- include/linux/cma.h | 2 +- kernel/dma/contiguous.c | 3 ++- mm/cma.c | 8 ++++---- mm/cma_debug.c | 2 +- 7 files changed, 11 insertions(+), 10 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv_builtin.c b/arch/powerpc/kvm/book3s_hv_builtin.c index d4a3f4da409b..fc6bb9630a9c 100644 --- a/arch/powerpc/kvm/book3s_hv_builtin.c +++ b/arch/powerpc/kvm/book3s_hv_builtin.c @@ -77,7 +77,7 @@ struct page *kvm_alloc_hpt_cma(unsigned long nr_pages) VM_BUG_ON(order_base_2(nr_pages) < KVM_CMA_CHUNK_ORDER - PAGE_SHIFT); return cma_alloc(kvm_cma, nr_pages, order_base_2(HPT_ALIGN_PAGES), - GFP_KERNEL); + false); } EXPORT_SYMBOL_GPL(kvm_alloc_hpt_cma); diff --git a/drivers/s390/char/vmcp.c b/drivers/s390/char/vmcp.c index 948ce82a7725..0fa1b6b1491a 100644 --- a/drivers/s390/char/vmcp.c +++ b/drivers/s390/char/vmcp.c @@ -68,7 +68,7 @@ static void vmcp_response_alloc(struct vmcp_session *session) * anymore the system won't work anyway. */ if (order > 2) - page = cma_alloc(vmcp_cma, nr_pages, 0, GFP_KERNEL); + page = cma_alloc(vmcp_cma, nr_pages, 0, false); if (page) { session->response = (char *)page_to_phys(page); session->cma_alloc = 1; diff --git a/drivers/staging/android/ion/ion_cma_heap.c b/drivers/staging/android/ion/ion_cma_heap.c index 49718c96bf9e..3fafd013d80a 100644 --- a/drivers/staging/android/ion/ion_cma_heap.c +++ b/drivers/staging/android/ion/ion_cma_heap.c @@ -39,7 +39,7 @@ static int ion_cma_allocate(struct ion_heap *heap, struct ion_buffer *buffer, if (align > CONFIG_CMA_ALIGNMENT) align = CONFIG_CMA_ALIGNMENT; - pages = cma_alloc(cma_heap->cma, nr_pages, align, GFP_KERNEL); + pages = cma_alloc(cma_heap->cma, nr_pages, align, false); if (!pages) return -ENOMEM; diff --git a/include/linux/cma.h b/include/linux/cma.h index bf90f0bb42bd..190184b5ff32 100644 --- a/include/linux/cma.h +++ b/include/linux/cma.h @@ -33,7 +33,7 @@ extern int cma_init_reserved_mem(phys_addr_t base, phys_addr_t size, const char *name, struct cma **res_cma); extern struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align, - gfp_t gfp_mask); + bool no_warn); extern bool cma_release(struct cma *cma, const struct page *pages, unsigned int count); extern int cma_for_each_area(int (*it)(struct cma *cma, void *data), void *data); diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c index d987dcd1bd56..19ea5d70150c 100644 --- a/kernel/dma/contiguous.c +++ b/kernel/dma/contiguous.c @@ -191,7 +191,8 @@ struct page *dma_alloc_from_contiguous(struct device *dev, size_t count, if (align > CONFIG_CMA_ALIGNMENT) align = CONFIG_CMA_ALIGNMENT; - return cma_alloc(dev_get_cma_area(dev), count, align, gfp_mask); + return cma_alloc(dev_get_cma_area(dev), count, align, + gfp_mask & __GFP_NOWARN); } /** diff --git a/mm/cma.c b/mm/cma.c index 5809bbe360d7..4cb76121a3ab 100644 --- a/mm/cma.c +++ b/mm/cma.c @@ -395,13 +395,13 @@ static inline void cma_debug_show_areas(struct cma *cma) { } * @cma: Contiguous memory region for which the allocation is performed. * @count: Requested number of pages. * @align: Requested alignment of pages (in PAGE_SIZE order). - * @gfp_mask: GFP mask to use during compaction + * @no_warn: Avoid printing message about failed allocation * * This function allocates part of contiguous memory on specific * contiguous memory area. */ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align, - gfp_t gfp_mask) + bool no_warn) { unsigned long mask, offset; unsigned long pfn = -1; @@ -447,7 +447,7 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align, pfn = cma->base_pfn + (bitmap_no << cma->order_per_bit); mutex_lock(&cma_mutex); ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA, - gfp_mask); + GFP_KERNEL | (no_warn ? __GFP_NOWARN : 0)); mutex_unlock(&cma_mutex); if (ret == 0) { page = pfn_to_page(pfn); @@ -466,7 +466,7 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align, trace_cma_alloc(pfn, page, count, align); - if (ret && !(gfp_mask & __GFP_NOWARN)) { + if (ret && !no_warn) { pr_err("%s: alloc failed, req-size: %zu pages, ret: %d\n", __func__, count, ret); cma_debug_show_areas(cma); diff --git a/mm/cma_debug.c b/mm/cma_debug.c index f23467291cfb..ad6723e9d110 100644 --- a/mm/cma_debug.c +++ b/mm/cma_debug.c @@ -139,7 +139,7 @@ static int cma_alloc_mem(struct cma *cma, int count) if (!mem) return -ENOMEM; - p = cma_alloc(cma, count, 0, GFP_KERNEL); + p = cma_alloc(cma, count, 0, false); if (!p) { kfree(mem); return -ENOMEM; -- 2.17.1

6 years, 6 months

[PATCH 2/2] dma: remove unsupported gfp_mask parameter from dma_alloc_from_contiguous()

by Marek Szyprowski

The CMA memory allocator doesn't support standard gfp flags for memory allocation, so there is no point having it as a parameter for dma_alloc_from_contiguous() function. Replace it by a boolean no_warn argument, which covers all the underlaying cma_alloc() function supports. This will help to avoid giving false feeling that this function supports standard gfp flags and callers can pass __GFP_ZERO to get zeroed buffer, what has already been an issue: see commit dd65a941f6ba ("arm64: dma-mapping: clear buffers allocated with FORCE_CONTIGUOUS flag"). Signed-off-by: Marek Szyprowski <m.szyprowski(a)samsung.com> --- arch/arm/mm/dma-mapping.c | 5 +++-- arch/arm64/mm/dma-mapping.c | 4 ++-- arch/xtensa/kernel/pci-dma.c | 2 +- drivers/iommu/amd_iommu.c | 2 +- drivers/iommu/intel-iommu.c | 3 ++- include/linux/dma-contiguous.h | 4 ++-- kernel/dma/contiguous.c | 7 +++---- kernel/dma/direct.c | 3 ++- 8 files changed, 16 insertions(+), 14 deletions(-) diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index be0fa7e39c26..121c6c3ba9e0 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -594,7 +594,7 @@ static void *__alloc_from_contiguous(struct device *dev, size_t size, struct page *page; void *ptr = NULL; - page = dma_alloc_from_contiguous(dev, count, order, gfp); + page = dma_alloc_from_contiguous(dev, count, order, gfp & __GFP_NOWARN); if (!page) return NULL; @@ -1294,7 +1294,8 @@ static struct page **__iommu_alloc_buffer(struct device *dev, size_t size, unsigned long order = get_order(size); struct page *page; - page = dma_alloc_from_contiguous(dev, count, order, gfp); + page = dma_alloc_from_contiguous(dev, count, order, + gfp & __GFP_NOWARN); if (!page) goto error; diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c index 61e93f0b5482..072c51fb07d7 100644 --- a/arch/arm64/mm/dma-mapping.c +++ b/arch/arm64/mm/dma-mapping.c @@ -355,7 +355,7 @@ static int __init atomic_pool_init(void) if (dev_get_cma_area(NULL)) page = dma_alloc_from_contiguous(NULL, nr_pages, - pool_size_order, GFP_KERNEL); + pool_size_order, false); else page = alloc_pages(GFP_DMA32, pool_size_order); @@ -573,7 +573,7 @@ static void *__iommu_alloc_attrs(struct device *dev, size_t size, struct page *page; page = dma_alloc_from_contiguous(dev, size >> PAGE_SHIFT, - get_order(size), gfp); + get_order(size), gfp & __GFP_NOWARN); if (!page) return NULL; diff --git a/arch/xtensa/kernel/pci-dma.c b/arch/xtensa/kernel/pci-dma.c index ba4640cc0093..b2c7ba91fb08 100644 --- a/arch/xtensa/kernel/pci-dma.c +++ b/arch/xtensa/kernel/pci-dma.c @@ -137,7 +137,7 @@ static void *xtensa_dma_alloc(struct device *dev, size_t size, if (gfpflags_allow_blocking(flag)) page = dma_alloc_from_contiguous(dev, count, get_order(size), - flag); + flag & __GFP_NOWARN); if (!page) page = alloc_pages(flag, get_order(size)); diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c index 64cfe854e0f5..5ec97ffb561a 100644 --- a/drivers/iommu/amd_iommu.c +++ b/drivers/iommu/amd_iommu.c @@ -2622,7 +2622,7 @@ static void *alloc_coherent(struct device *dev, size_t size, return NULL; page = dma_alloc_from_contiguous(dev, size >> PAGE_SHIFT, - get_order(size), flag); + get_order(size), flag & __GFP_NOWARN); if (!page) return NULL; } diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index 869321c594e2..dd2d343428ab 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -3746,7 +3746,8 @@ static void *intel_alloc_coherent(struct device *dev, size_t size, if (gfpflags_allow_blocking(flags)) { unsigned int count = size >> PAGE_SHIFT; - page = dma_alloc_from_contiguous(dev, count, order, flags); + page = dma_alloc_from_contiguous(dev, count, order, + flags & __GFP_NOWARN); if (page && iommu_no_mapping(dev) && page_to_phys(page) + size > dev->coherent_dma_mask) { dma_release_from_contiguous(dev, page, count); diff --git a/include/linux/dma-contiguous.h b/include/linux/dma-contiguous.h index 3c5a4cb3eb95..f247e8aa5e3d 100644 --- a/include/linux/dma-contiguous.h +++ b/include/linux/dma-contiguous.h @@ -112,7 +112,7 @@ static inline int dma_declare_contiguous(struct device *dev, phys_addr_t size, } struct page *dma_alloc_from_contiguous(struct device *dev, size_t count, - unsigned int order, gfp_t gfp_mask); + unsigned int order, bool no_warn); bool dma_release_from_contiguous(struct device *dev, struct page *pages, int count); @@ -145,7 +145,7 @@ int dma_declare_contiguous(struct device *dev, phys_addr_t size, static inline struct page *dma_alloc_from_contiguous(struct device *dev, size_t count, - unsigned int order, gfp_t gfp_mask) + unsigned int order, bool no_warn) { return NULL; } diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c index 19ea5d70150c..286d82329eb0 100644 --- a/kernel/dma/contiguous.c +++ b/kernel/dma/contiguous.c @@ -178,7 +178,7 @@ int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base, * @dev: Pointer to device for which the allocation is performed. * @count: Requested number of pages. * @align: Requested alignment of pages (in PAGE_SIZE order). - * @gfp_mask: GFP flags to use for this allocation. + * @no_warn: Avoid printing message about failed allocation. * * This function allocates memory buffer for specified device. It uses * device specific contiguous memory area if available or the default @@ -186,13 +186,12 @@ int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base, * function. */ struct page *dma_alloc_from_contiguous(struct device *dev, size_t count, - unsigned int align, gfp_t gfp_mask) + unsigned int align, bool no_warn) { if (align > CONFIG_CMA_ALIGNMENT) align = CONFIG_CMA_ALIGNMENT; - return cma_alloc(dev_get_cma_area(dev), count, align, - gfp_mask & __GFP_NOWARN); + return cma_alloc(dev_get_cma_area(dev), count, align, no_warn); } /** diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index 8be8106270c2..e0241beeb645 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -78,7 +78,8 @@ void *dma_direct_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle, again: /* CMA can be used only in the context which permits sleeping */ if (gfpflags_allow_blocking(gfp)) { - page = dma_alloc_from_contiguous(dev, count, page_order, gfp); + page = dma_alloc_from_contiguous(dev, count, page_order, + gfp & __GFP_NOWARN); if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) { dma_release_from_contiguous(dev, page, count); page = NULL; -- 2.17.1

6 years, 6 months

[PATCH 0/2] CMA: remove unsupported gfp mask parameter

by Marek Szyprowski

Dear All, The CMA related functions cma_alloc() and dma_alloc_from_contiguous() have gfp mask parameter, but sadly they only support __GFP_NOWARN flag. This gave their users a misleading feeling that any standard memory allocation flags are supported, what resulted in the security issue when caller have set __GFP_ZERO flag and expected the buffer to be cleared. This patchset changes gfp_mask parameter to a simple boolean no_warn argument, which covers all the underlaying code supports. This patchset is a result of the following discussion: https://patchwork.kernel.org/patch/10461919/ Best regards Marek Szyprowski Samsung R&D Institute Poland Patch summary: Marek Szyprowski (2): mm/cma: remove unsupported gfp_mask parameter from cma_alloc() dma: remove unsupported gfp_mask parameter from dma_alloc_from_contiguous() arch/arm/mm/dma-mapping.c | 5 +++-- arch/arm64/mm/dma-mapping.c | 4 ++-- arch/powerpc/kvm/book3s_hv_builtin.c | 2 +- arch/xtensa/kernel/pci-dma.c | 2 +- drivers/iommu/amd_iommu.c | 2 +- drivers/iommu/intel-iommu.c | 3 ++- drivers/s390/char/vmcp.c | 2 +- drivers/staging/android/ion/ion_cma_heap.c | 2 +- include/linux/cma.h | 2 +- include/linux/dma-contiguous.h | 4 ++-- kernel/dma/contiguous.c | 6 +++--- kernel/dma/direct.c | 3 ++- mm/cma.c | 8 ++++---- mm/cma_debug.c | 2 +- 14 files changed, 25 insertions(+), 22 deletions(-) -- 2.17.1

6 years, 6 months

Re: [Linaro-mm-sig] [PATCH v6] Add udmabuf misc device

by Gerd Hoffmann

On Wed, Jul 04, 2018 at 09:26:39AM +0200, Tomeu Vizoso wrote: > On 07/04/2018 07:53 AM, Gerd Hoffmann wrote: > > On Tue, Jul 03, 2018 at 10:37:57AM +0200, Daniel Vetter wrote: > > > On Tue, Jul 03, 2018 at 09:53:58AM +0200, Gerd Hoffmann wrote: > > > > A driver to let userspace turn memfd regions into dma-bufs. > > > > > > > > Use case: Allows qemu create dmabufs for the vga framebuffer or > > > > virtio-gpu ressources. Then they can be passed around to display > > > > those guest things on the host. To spice client for classic full > > > > framebuffer display, and hopefully some day to wayland server for > > > > seamless guest window display. > > > > > > > > qemu test branch: > > > > https://git.kraxel.org/cgit/qemu/log/?h=sirius/udmabuf > > > > > > > > Cc: David Airlie <airlied(a)linux.ie> > > > > Cc: Tomeu Vizoso <tomeu.vizoso(a)collabora.com> > > > > Cc: Laurent Pinchart <laurent.pinchart(a)ideasonboard.com> > > > > Cc: Daniel Vetter <daniel(a)ffwll.ch> > > > > Signed-off-by: Gerd Hoffmann <kraxel(a)redhat.com> > > > > > > I think some ack for a 2nd use-case, like virtio-wl or whatever would be > > > really cool. To give us some assurance that this is generically useful. > > > > Tomeu? Laurent? > > Sorry, but I think I will need some help to understand how this could help > in the virtio-wl case [adding Zach Reizner to CC]. > > Any graphics buffers that are allocated with memfd will be shared with the > compositor via wl_shm, without need for dmabufs. Within one machine, yes. Once virtualization is added to the mix things become more complicated ... When using virtio-gpu the guest will allocate graphics buffers from normal (guest) ram, then register these buffers (which are allowed to be scattered) with the host as resource. qemu can use memfd to allocate guest ram. Now, with the help of udmabuf, qemu can create a *host* dma-buf for the *guest* graphics buffer. That dma-buf can be used by qemu internally (mmap it to get a linear mapping of the resource, to avoid copying). It can be passed on to spice-client, to display the guest framebuffer. And I think it could also be quite useful to pass guest wayland windows to the host compositor, without mapping host-allocated buffers into the guest, so we don't have do deal with the "find some address space for the mapping" issue in the first place. There are more things needed to complete this of course, but it's a building block ... cheers, Gerd

6 years, 6 months

[PATCH 5/5] dma-fence: Polish kernel-doc for dma-fence.c

by Daniel Vetter

- Intro section that links to how this is exposed to userspace. - Lots more hyperlinks. - Minor clarifications and style polish v2: Add misplaced hunk of kerneldoc from a different patch. Signed-off-by: Daniel Vetter <daniel.vetter(a)ffwll.ch> Cc: Sumit Semwal <sumit.semwal(a)linaro.org> Cc: Gustavo Padovan <gustavo(a)padovan.org> Cc: linux-media(a)vger.kernel.org Cc: linaro-mm-sig(a)lists.linaro.org --- Documentation/driver-api/dma-buf.rst | 6 ++ drivers/dma-buf/dma-fence.c | 147 +++++++++++++++++++-------- 2 files changed, 109 insertions(+), 44 deletions(-) diff --git a/Documentation/driver-api/dma-buf.rst b/Documentation/driver-api/dma-buf.rst index dc384f2f7f34..b541e97c7ab1 100644 --- a/Documentation/driver-api/dma-buf.rst +++ b/Documentation/driver-api/dma-buf.rst @@ -130,6 +130,12 @@ Reservation Objects DMA Fences ---------- +.. kernel-doc:: drivers/dma-buf/dma-fence.c + :doc: DMA fences overview + +DMA Fences Functions Reference +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + .. kernel-doc:: drivers/dma-buf/dma-fence.c :export: diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c index 7a92f85a4cec..1551ca7df394 100644 --- a/drivers/dma-buf/dma-fence.c +++ b/drivers/dma-buf/dma-fence.c @@ -38,12 +38,43 @@ EXPORT_TRACEPOINT_SYMBOL(dma_fence_enable_signal); */ static atomic64_t dma_fence_context_counter = ATOMIC64_INIT(0); +/** + * DOC: DMA fences overview + * + * DMA fences, represented by &struct dma_fence, are the kernel internal + * synchronization primitive for DMA operations like GPU rendering, video + * encoding/decoding, or displaying buffers on a screen. + * + * A fence is initialized using dma_fence_init() and completed using + * dma_fence_signal(). Fences are associated with a context, allocated through + * dma_fence_context_alloc(), and all fences on the same context are + * fully ordered. + * + * Since the purposes of fences is to facilitate cross-device and + * cross-application synchronization, there's multiple ways to use one: + * + * - Individual fences can be exposed as a &sync_file, accessed as a file + * descriptor from userspace, created by calling sync_file_create(). This is + * called explicit fencing, since userspace passes around explicit + * synchronization points. + * + * - Some subsystems also have their own explicit fencing primitives, like + * &drm_syncobj. Compared to &sync_file, a &drm_syncobj allows the underlying + * fence to be updated. + * + * - Then there's also implicit fencing, where the synchronization points are + * implicitly passed around as part of shared &dma_buf instances. Such + * implicit fences are stored in &struct reservation_object through the + * &dma_buf.resv pointer. + */ + /** * dma_fence_context_alloc - allocate an array of fence contexts - * @num: [in] amount of contexts to allocate + * @num: amount of contexts to allocate * - * This function will return the first index of the number of fences allocated. - * The fence context is used for setting fence->context to a unique number. + * This function will return the first index of the number of fence contexts + * allocated. The fence context is used for setting &dma_fence.context to a + * unique number by passing the context to dma_fence_init(). */ u64 dma_fence_context_alloc(unsigned num) { @@ -59,10 +90,14 @@ EXPORT_SYMBOL(dma_fence_context_alloc); * Signal completion for software callbacks on a fence, this will unblock * dma_fence_wait() calls and run all the callbacks added with * dma_fence_add_callback(). Can be called multiple times, but since a fence - * can only go from unsignaled to signaled state, it will only be effective - * the first time. + * can only go from the unsignaled to the signaled state and not back, it will + * only be effective the first time. + * + * Unlike dma_fence_signal(), this function must be called with &dma_fence.lock + * held. * - * Unlike dma_fence_signal, this function must be called with fence->lock held. + * Returns 0 on success and a negative error value when @fence has been + * signalled already. */ int dma_fence_signal_locked(struct dma_fence *fence) { @@ -102,8 +137,11 @@ EXPORT_SYMBOL(dma_fence_signal_locked); * Signal completion for software callbacks on a fence, this will unblock * dma_fence_wait() calls and run all the callbacks added with * dma_fence_add_callback(). Can be called multiple times, but since a fence - * can only go from unsignaled to signaled state, it will only be effective - * the first time. + * can only go from the unsignaled to the signaled state and not back, it will + * only be effective the first time. + * + * Returns 0 on success and a negative error value when @fence has been + * signalled already. */ int dma_fence_signal(struct dma_fence *fence) { @@ -136,9 +174,9 @@ EXPORT_SYMBOL(dma_fence_signal); /** * dma_fence_wait_timeout - sleep until the fence gets signaled * or until timeout elapses - * @fence: [in] the fence to wait on - * @intr: [in] if true, do an interruptible wait - * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT + * @fence: the fence to wait on + * @intr: if true, do an interruptible wait + * @timeout: timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT * * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the * remaining timeout in jiffies on success. Other error values may be @@ -148,6 +186,8 @@ EXPORT_SYMBOL(dma_fence_signal); * directly or indirectly (buf-mgr between reservation and committing) * holds a reference to the fence, otherwise the fence might be * freed before return, resulting in undefined behavior. + * + * See also dma_fence_wait() and dma_fence_wait_any_timeout(). */ signed long dma_fence_wait_timeout(struct dma_fence *fence, bool intr, signed long timeout) @@ -167,6 +207,13 @@ dma_fence_wait_timeout(struct dma_fence *fence, bool intr, signed long timeout) } EXPORT_SYMBOL(dma_fence_wait_timeout); +/** + * dma_fence_release - default relese function for fences + * @kref: &dma_fence.recfount + * + * This is the default release functions for &dma_fence. Drivers shouldn't call + * this directly, but instead call dma_fence_put(). + */ void dma_fence_release(struct kref *kref) { struct dma_fence *fence = @@ -184,6 +231,13 @@ void dma_fence_release(struct kref *kref) } EXPORT_SYMBOL(dma_fence_release); +/** + * dma_fence_free - default release function for &dma_fence. + * @fence: fence to release + * + * This is the default implementation for &dma_fence_ops.release. It calls + * kfree_rcu() on @fence. + */ void dma_fence_free(struct dma_fence *fence) { kfree_rcu(fence, rcu); @@ -192,10 +246,11 @@ EXPORT_SYMBOL(dma_fence_free); /** * dma_fence_enable_sw_signaling - enable signaling on fence - * @fence: [in] the fence to enable + * @fence: the fence to enable * - * this will request for sw signaling to be enabled, to make the fence - * complete as soon as possible + * This will request for sw signaling to be enabled, to make the fence + * complete as soon as possible. This calls &dma_fence_ops.enable_signaling + * internally. */ void dma_fence_enable_sw_signaling(struct dma_fence *fence) { @@ -220,24 +275,24 @@ EXPORT_SYMBOL(dma_fence_enable_sw_signaling); /** * dma_fence_add_callback - add a callback to be called when the fence * is signaled - * @fence: [in] the fence to wait on - * @cb: [in] the callback to register - * @func: [in] the function to call + * @fence: the fence to wait on + * @cb: the callback to register + * @func: the function to call * - * cb will be initialized by dma_fence_add_callback, no initialization + * @cb will be initialized by dma_fence_add_callback(), no initialization * by the caller is required. Any number of callbacks can be registered * to a fence, but a callback can only be registered to one fence at a time. * * Note that the callback can be called from an atomic context. If * fence is already signaled, this function will return -ENOENT (and - * *not* call the callback) + * *not* call the callback). * * Add a software callback to the fence. Same restrictions apply to - * refcount as it does to dma_fence_wait, however the caller doesn't need to - * keep a refcount to fence afterwards: when software access is enabled, - * the creator of the fence is required to keep the fence alive until - * after it signals with dma_fence_signal. The callback itself can be called - * from irq context. + * refcount as it does to dma_fence_wait(), however the caller doesn't need to + * keep a refcount to fence afterward dma_fence_add_callback() has returned: + * when software access is enabled, the creator of the fence is required to keep + * the fence alive until after it signals with dma_fence_signal(). The callback + * itself can be called from irq context. * * Returns 0 in case of success, -ENOENT if the fence is already signaled * and -EINVAL in case of error. @@ -286,7 +341,7 @@ EXPORT_SYMBOL(dma_fence_add_callback); /** * dma_fence_get_status - returns the status upon completion - * @fence: [in] the dma_fence to query + * @fence: the dma_fence to query * * This wraps dma_fence_get_status_locked() to return the error status * condition on a signaled fence. See dma_fence_get_status_locked() for more @@ -311,8 +366,8 @@ EXPORT_SYMBOL(dma_fence_get_status); /** * dma_fence_remove_callback - remove a callback from the signaling list - * @fence: [in] the fence to wait on - * @cb: [in] the callback to remove + * @fence: the fence to wait on + * @cb: the callback to remove * * Remove a previously queued callback from the fence. This function returns * true if the callback is successfully removed, or false if the fence has @@ -323,6 +378,9 @@ EXPORT_SYMBOL(dma_fence_get_status); * doing, since deadlocks and race conditions could occur all too easily. For * this reason, it should only ever be done on hardware lockup recovery, * with a reference held to the fence. + * + * Behaviour is undefined if @cb has not been added to @fence using + * dma_fence_add_callback() beforehand. */ bool dma_fence_remove_callback(struct dma_fence *fence, struct dma_fence_cb *cb) @@ -359,9 +417,9 @@ dma_fence_default_wait_cb(struct dma_fence *fence, struct dma_fence_cb *cb) /** * dma_fence_default_wait - default sleep until the fence gets signaled * or until timeout elapses - * @fence: [in] the fence to wait on - * @intr: [in] if true, do an interruptible wait - * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT + * @fence: the fence to wait on + * @intr: if true, do an interruptible wait + * @timeout: timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT * * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or the * remaining timeout in jiffies on success. If timeout is zero the value one is @@ -454,12 +512,12 @@ dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count, /** * dma_fence_wait_any_timeout - sleep until any fence gets signaled * or until timeout elapses - * @fences: [in] array of fences to wait on - * @count: [in] number of fences to wait on - * @intr: [in] if true, do an interruptible wait - * @timeout: [in] timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT - * @idx: [out] the first signaled fence index, meaningful only on - * positive return + * @fences: array of fences to wait on + * @count: number of fences to wait on + * @intr: if true, do an interruptible wait + * @timeout: timeout value in jiffies, or MAX_SCHEDULE_TIMEOUT + * @idx: used to store the first signaled fence index, meaningful only on + * positive return * * Returns -EINVAL on custom fence wait implementation, -ERESTARTSYS if * interrupted, 0 if the wait timed out, or the remaining timeout in jiffies @@ -468,6 +526,8 @@ dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count, * Synchronous waits for the first fence in the array to be signaled. The * caller needs to hold a reference to all fences in the array, otherwise a * fence might be freed before return, resulting in undefined behavior. + * + * See also dma_fence_wait() and dma_fence_wait_timeout(). */ signed long dma_fence_wait_any_timeout(struct dma_fence **fences, uint32_t count, @@ -540,19 +600,18 @@ EXPORT_SYMBOL(dma_fence_wait_any_timeout); /** * dma_fence_init - Initialize a custom fence. - * @fence: [in] the fence to initialize - * @ops: [in] the dma_fence_ops for operations on this fence - * @lock: [in] the irqsafe spinlock to use for locking this fence - * @context: [in] the execution context this fence is run on - * @seqno: [in] a linear increasing sequence number for this context + * @fence: the fence to initialize + * @ops: the dma_fence_ops for operations on this fence + * @lock: the irqsafe spinlock to use for locking this fence + * @context: the execution context this fence is run on + * @seqno: a linear increasing sequence number for this context * * Initializes an allocated fence, the caller doesn't have to keep its * refcount after committing with this fence, but it will need to hold a - * refcount again if dma_fence_ops.enable_signaling gets called. This can - * be used for other implementing other types of fence. + * refcount again if &dma_fence_ops.enable_signaling gets called. * * context and seqno are used for easy comparison between fences, allowing - * to check which fence is later by simply using dma_fence_later. + * to check which fence is later by simply using dma_fence_later(). */ void dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops, -- 2.18.0

6 years, 6 months

Re: [Linaro-mm-sig] [PATCH] dma-buf: Move BUG_ON from _add_shared_fence to _add_shared_inplace

by Christian König

Am 04.07.2018 um 11:09 schrieb Michel Dänzer: > On 2018-07-04 10:31 AM, Christian König wrote: >> Am 26.06.2018 um 16:31 schrieb Michel Dänzer: >>> From: Michel Dänzer <michel.daenzer(a)amd.com> >>> >>> Fixes the BUG_ON spuriously triggering under the following >>> circumstances: >>> >>> * ttm_eu_reserve_buffers processes a list containing multiple BOs using >>> the same reservation object, so it calls >>> reservation_object_reserve_shared with that reservation object once >>> for each such BO. >>> * In reservation_object_reserve_shared, old->shared_count == >>> old->shared_max - 1, so obj->staged is freed in preparation of an >>> in-place update. >>> * ttm_eu_fence_buffer_objects calls reservation_object_add_shared_fence >>> once for each of the BOs above, always with the same fence. >>> * The first call adds the fence in the remaining free slot, after which >>> old->shared_count == old->shared_max. >> Well, the explanation here is not correct. For multiple BOs using the >> same reservation object we won't call >> reservation_object_add_shared_fence() multiple times because we move >> those to the duplicates list in ttm_eu_reserve_buffers(). >> >> But this bug can still happen because we call >> reservation_object_add_shared_fence() manually with fences for the same >> context in a couple of places. >> >> One prominent case which comes to my mind are for the VM BOs during >> updates. Another possibility are VRAM BOs which need to be cleared. > Thanks. How about the following: > > * ttm_eu_reserve_buffers calls reservation_object_reserve_shared. > * In reservation_object_reserve_shared, shared_count == shared_max - 1, > so obj->staged is freed in preparation of an in-place update. > * ttm_eu_fence_buffer_objects calls reservation_object_add_shared_fence, > after which shared_count == shared_max. > * The amdgpu driver also calls reservation_object_add_shared_fence for > the same reservation object, and the BUG_ON triggers. I would rather completely drop the reference to the ttm_eu_* functions, cause those wrappers are completely unrelated to the problem. Instead let's just note something like the following: * When reservation_object_reserve_shared is called with shared_count == shared_max - 1, so obj->staged is freed in preparation of an in-place update. * Now reservation_object_add_shared_fence is called with the first fence and after that shared_count == shared_max. * After that reservation_object_add_shared_fence can be called with follow up fences from the same context, but since shared_count == shared_max we would run into this BUG_ON. > However, nothing bad would happen in > reservation_object_add_shared_inplace, since all fences use the same > context, so they can only occupy a single slot. > > Prevent this by moving the BUG_ON to where an overflow would actually > happen (e.g. if a buggy caller didn't call > reservation_object_reserve_shared before). > > > Also, I'll add a reference to https://bugs.freedesktop.org/106418 in v2, > as I suspect this fix is necessary under the circumstances described > there as well. The rest sounds good to me. Regards, Christian.

6 years, 6 months

Re: [Linaro-mm-sig] [PATCH] dma-buf: Move BUG_ON from _add_shared_fence to _add_shared_inplace

by Christian König

Am 26.06.2018 um 16:31 schrieb Michel Dänzer: > From: Michel Dänzer <michel.daenzer(a)amd.com> > > Fixes the BUG_ON spuriously triggering under the following > circumstances: > > * ttm_eu_reserve_buffers processes a list containing multiple BOs using > the same reservation object, so it calls > reservation_object_reserve_shared with that reservation object once > for each such BO. > * In reservation_object_reserve_shared, old->shared_count == > old->shared_max - 1, so obj->staged is freed in preparation of an > in-place update. > * ttm_eu_fence_buffer_objects calls reservation_object_add_shared_fence > once for each of the BOs above, always with the same fence. > * The first call adds the fence in the remaining free slot, after which > old->shared_count == old->shared_max. Well, the explanation here is not correct. For multiple BOs using the same reservation object we won't call reservation_object_add_shared_fence() multiple times because we move those to the duplicates list in ttm_eu_reserve_buffers(). But this bug can still happen because we call reservation_object_add_shared_fence() manually with fences for the same context in a couple of places. One prominent case which comes to my mind are for the VM BOs during updates. Another possibility are VRAM BOs which need to be cleared. > > In the next call to reservation_object_add_shared_fence, the BUG_ON > triggers. However, nothing bad would happen in > reservation_object_add_shared_inplace, since the fence is already in the > reservation object. > > Prevent this by moving the BUG_ON to where an overflow would actually > happen (e.g. if a buggy caller didn't call > reservation_object_reserve_shared before). > > Cc: stable(a)vger.kernel.org > Signed-off-by: Michel Dänzer <michel.daenzer(a)amd.com> Reviewed-by: Christian König <christian.koenig(a)amd.com>. Regards, Christian. > --- > drivers/dma-buf/reservation.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c > index 314eb1071cce..532545b9488e 100644 > --- a/drivers/dma-buf/reservation.c > +++ b/drivers/dma-buf/reservation.c > @@ -141,6 +141,7 @@ reservation_object_add_shared_inplace(struct reservation_object *obj, > if (signaled) { > RCU_INIT_POINTER(fobj->shared[signaled_idx], fence); > } else { > + BUG_ON(fobj->shared_count >= fobj->shared_max); > RCU_INIT_POINTER(fobj->shared[fobj->shared_count], fence); > fobj->shared_count++; > } > @@ -230,10 +231,9 @@ void reservation_object_add_shared_fence(struct reservation_object *obj, > old = reservation_object_get_list(obj); > obj->staged = NULL; > > - if (!fobj) { > - BUG_ON(old->shared_count >= old->shared_max); > + if (!fobj) > reservation_object_add_shared_inplace(obj, old, fence); > - } else > + else > reservation_object_add_shared_replace(obj, old, fobj, fence); > } > EXPORT_SYMBOL(reservation_object_add_shared_fence);

6 years, 6 months

First step towards unpinned DMA-buf operation.

by Christian König

[As requested by Daniel cross posting to intel-gfx as well]. This set is the first step towards allowing to use a DMA-buf without actually pinning the underlying resources. This in turn the the ground work for PCIe P2P operations as well as quite a bunch of other use cases. The idea is that we build the support for unpinned operation around the already present reservation lock in the DMA-buf object. For this we now grab the reservation object lock while mapping and unmapping DMA-bufs. The down side is that all implementations as well as users of DMA-buf needs to be audited to make sure that we don't run into double locking or lock inversions. So please test and/or comment and report back how badly lockdep complains :) Thanks, Christian.

6 years, 6 months

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