Linaro-mm-sig

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24 participants
2727 discussions

Re: [PATCH v5] drm/test: add a test suite for GEM objects backed by shmem

by Guenter Roeck

On Thu, Feb 22, 2024 at 05:33:48PM +0100, Marco Pagani wrote: > > > > In this context, the TTM unit tests fail as well in qemu, with worse result: > > It seems there is some bad cleanup after a failed test case, causing list > > corruptions in the drm core and ultimately a crash. I don't know if this > > is also caused by the missing dma_mask initialization. > > > > That's interesting. Which --arch argument are you using to run the > tests with QEMU? Example (I am not sure if any of those parameters matters; it is just one of my tests): qemu-system-x86_64 -kernel arch/x86/boot/bzImage -M q35 -cpu IvyBridge \ -no-reboot -snapshot -smp 2 \ -device e1000,netdev=net0 -netdev user,id=net0 -m 512 \ -drive file=rootfs.ext2,format=raw,if=ide \ --append "earlycon=uart8250,io,0x3f8,9600n8 root=/dev/sda1 console=ttyS0" \ -d unimp,guest_errors -nographic -monitor none This results in: [ ... ] [ 5.989496] KTAP version 1 [ 5.989639] # Subtest: ttm_device [ 5.989711] # module: ttm_device_test [ 5.989760] 1..5 [ 6.002044] ok 1 ttm_device_init_basic [ 6.013557] ok 2 ttm_device_init_multiple ILLOPC: ffffffffb8ac9350: 0f 0b [ 6.022481] ok 3 ttm_device_fini_basic [ 6.026172] ------------[ cut here ]------------ [ 6.026315] WARNING: CPU: 1 PID: 1575 at drivers/gpu/drm/ttm/ttm_device.c:206 ttm_device_init+0x170/0x190 ... [ 6.135016] ok 3 Above the allocation limit [ 6.138759] ------------[ cut here ]------------ [ 6.138925] WARNING: CPU: 1 PID: 1595 at kernel/dma/mapping.c:503 dma_alloc_attrs+0xf6/0x100 ... [ 6.143850] # ttm_pool_alloc_basic: ASSERTION FAILED at drivers/gpu/drm/ttm/tests/ttm_pool_test.c:162 [ 6.143850] Expected err == 0, but [ 6.143850] err == -12 (0xfffffffffffffff4) [ 6.148824] not ok 4 One page, with coherent DMA mappings enabled From there things go downhill. [ 6.152821] list_add corruption. prev->next should be next (ffffffffbbd53950), but was 0000000000000000. (prev=ffff8af1c38f9e20). and so on until the emulation crashes. Guenter

1 year, 2 months

Re: [PATCH v5] drm/test: add a test suite for GEM objects backed by shmem

by Guenter Roeck

Hi Marco, On 2/22/24 07:32, Marco Pagani wrote: > > > On 2024-02-18 16:49, Guenter Roeck wrote: >> Hi, >> >> On Thu, Nov 30, 2023 at 06:14:16PM +0100, Marco Pagani wrote: >>> This patch introduces an initial KUnit test suite for GEM objects >>> backed by shmem buffers. >>> >>> Suggested-by: Javier Martinez Canillas <javierm(a)redhat.com> >>> Signed-off-by: Marco Pagani <marpagan(a)redhat.com> >> >> When running this in qemu, I get lots of warnings backtraces in the drm >> core. >> >> WARNING: CPU: 0 PID: 1341 at drivers/gpu/drm/drm_gem_shmem_helper.c:327 >> WARNING: CPU: 0 PID: 1341 at drivers/gpu/drm/drm_gem_shmem_helper.c:173 >> WARNING: CPU: 0 PID: 1341 at drivers/gpu/drm/drm_gem_shmem_helper.c:385 >> WARNING: CPU: 0 PID: 1341 at drivers/gpu/drm/drm_gem_shmem_helper.c:211 >> WARNING: CPU: 0 PID: 1345 at kernel/dma/mapping.c:194 >> WARNING: CPU: 0 PID: 1347 at drivers/gpu/drm/drm_gem_shmem_helper.c:429 >> WARNING: CPU: 0 PID: 1349 at drivers/gpu/drm/drm_gem_shmem_helper.c:445 >> >> It looks like dma_resv_assert_held() asserts each time it is executed. >> The backtrace in kernel/dma/mapping.c is triggered by >> if (WARN_ON_ONCE(!dev->dma_mask)) >> return 0; >> in __dma_map_sg_attrs(). >> >> Is this a possible problem in the test code, or can it be caused by >> some limitations or bugs in the qemu emulation ? If so, do you have any >> thoughts or ideas what those limitations / bugs might be ? > > Hi Guenter, > > Thanks for reporting this issue. As you correctly noted, the warnings appear to > be caused by the dma_mask in the mock device being uninitialized. I'll send a > patch to fix it soon. > Thanks a lot for the update. In this context, the TTM unit tests fail as well in qemu, with worse result: It seems there is some bad cleanup after a failed test case, causing list corruptions in the drm core and ultimately a crash. I don't know if this is also caused by the missing dma_mask initialization. Thanks, Guenter

1 year, 2 months

[PATCH v2] udmabuf: Fix a potential (and unlikely) access to unallocated memory

by Christophe JAILLET

If 'list_limit' is set to a very high value, 'lsize' computation could overflow if 'head.count' is big enough. In such a case, udmabuf_create() would access to memory beyond 'list'. Use memdup_array_user() which checks for overflow. While at it, include <linux/string.h>. Fixes: fbb0de795078 ("Add udmabuf misc device") Signed-off-by: Christophe JAILLET <christophe.jaillet(a)wanadoo.fr> --- v2: - Use memdup_array_user() [Kees Cook] - Use sizeof(*list) [Gustavo A. R. Silva] - Add include <linux/string.h> v1: https://lore.kernel.org/all/3e37f05c7593f1016f0a46de188b3357cbbd0c0b.169506… Signed-off-by: Christophe JAILLET <christophe.jaillet(a)wanadoo.fr> --- drivers/dma-buf/udmabuf.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c index c40645999648..5728948ea6f2 100644 --- a/drivers/dma-buf/udmabuf.c +++ b/drivers/dma-buf/udmabuf.c @@ -11,6 +11,7 @@ #include <linux/module.h> #include <linux/shmem_fs.h> #include <linux/slab.h> +#include <linux/string.h> #include <linux/udmabuf.h> #include <linux/vmalloc.h> #include <linux/iosys-map.h> @@ -314,14 +315,13 @@ static long udmabuf_ioctl_create_list(struct file *filp, unsigned long arg) struct udmabuf_create_list head; struct udmabuf_create_item *list; int ret = -EINVAL; - u32 lsize; if (copy_from_user(&head, (void __user *)arg, sizeof(head))) return -EFAULT; if (head.count > list_limit) return -EINVAL; - lsize = sizeof(struct udmabuf_create_item) * head.count; - list = memdup_user((void __user *)(arg + sizeof(head)), lsize); + list = memdup_array_user((void __user *)(arg + sizeof(head)), + sizeof(*list), head.count); if (IS_ERR(list)) return PTR_ERR(list); -- 2.43.2

1 year, 2 months

Re: [PATCH v5] drm/test: add a test suite for GEM objects backed by shmem

by Guenter Roeck

Hi, On Thu, Nov 30, 2023 at 06:14:16PM +0100, Marco Pagani wrote: > This patch introduces an initial KUnit test suite for GEM objects > backed by shmem buffers. > > Suggested-by: Javier Martinez Canillas <javierm(a)redhat.com> > Signed-off-by: Marco Pagani <marpagan(a)redhat.com> When running this in qemu, I get lots of warnings backtraces in the drm core. WARNING: CPU: 0 PID: 1341 at drivers/gpu/drm/drm_gem_shmem_helper.c:327 WARNING: CPU: 0 PID: 1341 at drivers/gpu/drm/drm_gem_shmem_helper.c:173 WARNING: CPU: 0 PID: 1341 at drivers/gpu/drm/drm_gem_shmem_helper.c:385 WARNING: CPU: 0 PID: 1341 at drivers/gpu/drm/drm_gem_shmem_helper.c:211 WARNING: CPU: 0 PID: 1345 at kernel/dma/mapping.c:194 WARNING: CPU: 0 PID: 1347 at drivers/gpu/drm/drm_gem_shmem_helper.c:429 WARNING: CPU: 0 PID: 1349 at drivers/gpu/drm/drm_gem_shmem_helper.c:445 It looks like dma_resv_assert_held() asserts each time it is executed. The backtrace in kernel/dma/mapping.c is triggered by if (WARN_ON_ONCE(!dev->dma_mask)) return 0; in __dma_map_sg_attrs(). Is this a possible problem in the test code, or can it be caused by some limitations or bugs in the qemu emulation ? If so, do you have any thoughts or ideas what those limitations / bugs might be ? Thanks, Guenter

1 year, 2 months

[PATCH] dma-buf: try to catch swiotlb bounce buffers

by Daniel Vetter

They rather fundamentally break the entire concept of zero copy, so if an exporter manages to hand these out things will break all over. Luckily there's not too many case that use swiotlb_sync_single_for_device/cpu(): - The generic iommu dma-api code in drivers/iommu/dma-iommu.c. We can catch that with sg_dma_is_swiotlb() reliably. - The generic direct dma code in kernel/dma/direct.c. We can mostly catch that with looking for a NULL dma_ops, except for some powerpc special cases. - Xen, which I don't bother to catch here. Implement these checks in dma_buf_map_attachment when CONFIG_DMA_API_DEBUG is enabled. Signed-off-by: Daniel Vetter <daniel.vetter(a)intel.com> Cc: Sumit Semwal <sumit.semwal(a)linaro.org> Cc: "Christian König" <christian.koenig(a)amd.com> Cc: linux-media(a)vger.kernel.org Cc: linaro-mm-sig(a)lists.linaro.org Cc: Paul Cercueil <paul(a)crapouillou.net> --- Entirely untested, but since I sent the mail with the idea I figured I might as well type it up after I realized there's a lot fewer cases to check. That is, if I haven't completely misread the dma-api and swiotlb code. -Sima --- drivers/dma-buf/dma-buf.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index d1e7f823fbdb..d6f95523f995 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -28,6 +28,12 @@ #include <linux/mount.h> #include <linux/pseudo_fs.h> +#ifdef CONFIG_DMA_API_DEBUG +#include <linux/dma-direct.h> +#include <linux/dma-map-ops.h> +#include <linux/swiotlb.h> +#endif + #include <uapi/linux/dma-buf.h> #include <uapi/linux/magic.h> @@ -1149,10 +1155,13 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach, #ifdef CONFIG_DMA_API_DEBUG if (!IS_ERR(sg_table)) { struct scatterlist *sg; + struct device *dev = attach->dev; u64 addr; int len; int i; + bool is_direct_dma = !get_dma_ops(dev); + for_each_sgtable_dma_sg(sg_table, sg, i) { addr = sg_dma_address(sg); len = sg_dma_len(sg); @@ -1160,7 +1169,15 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach, pr_debug("%s: addr %llx or len %x is not page aligned!\n", __func__, addr, len); } + + if (is_direct_dma) { + phys_addr_t paddr = dma_to_phys(dev, addr); + + WARN_ON_ONCE(is_swiotlb_buffer(dev, paddr)); + } } + + WARN_ON_ONCE(sg_dma_is_swiotlb(sg)); } #endif /* CONFIG_DMA_API_DEBUG */ return sg_table; -- 2.43.0

1 year, 2 months

[PATCH v5 0/6] usb: gadget: functionfs: DMABUF import interface

by Paul Cercueil

Hi, This is the v5 of my patchset that adds a new DMABUF import interface to FunctionFS. Daniel / Sima suggested that I should cache the dma_buf_attachment while the DMABUF is attached to the interface, instead of mapping/unmapping the DMABUF for every transfer (also because unmapping is not possible in the dma_fence's critical section). This meant having to add new dma_buf_begin_access() / dma_buf_end_access() functions that the driver can call to ensure cache coherency. These two functions are provided by the new patch [1/6], and an implementation for udmabuf was added in [2/6] - see the changelog below. This patchset was successfully tested with CONFIG_LOCKDEP, no errors were reported in dmesg while using the interface. This interface is being used at Analog Devices, to transfer data from high-speed transceivers to USB in a zero-copy fashion, using also the DMABUF import interface to the IIO subsystem which is being upstreamed in parallel [1]. The two are used by the Libiio software [2]. On a ZCU102 board with a FMComms3 daughter board, using the combination of these two new interfaces yields a drastic improvement of the throughput, from about 127 MiB/s using IIO's buffer read/write interface + read/write to the FunctionFS endpoints, to about 274 MiB/s when passing around DMABUFs, for a lower CPU usage (0.85 load avg. before, vs. 0.65 after). Right now, *technically* there are no users of this interface, as Analog Devices wants to wait until both interfaces are accepted upstream to merge the DMABUF code in Libiio into the main branch, and Jonathan wants to wait and see if this patchset is accepted to greenlight the DMABUF interface in IIO as well. I think this isn't really a problem; once everybody is happy with its part of the cake, we can merge them all at once. This is obviously for 5.9, and based on next-20240119. Changelog: - [1/6]: New patch - [2/6]: New patch - [5/6]: - Cache the dma_buf_attachment while the DMABUF is attached. - Use dma_buf_begin/end_access() to ensure that the DMABUF data will be coherent to the hardware. - Remove comment about cache-management and dma_buf_unmap_attachment(), since we now use dma_buf_begin/end_access(). - Select DMA_SHARED_BUFFER in Kconfig entry - Add Christian's ACK Cheers, -Paul [1] https://lore.kernel.org/linux-iio/219abc43b4fdd4a13b307ed2efaa0e6869e68e3f.… [2] https://github.com/analogdevicesinc/libiio/tree/pcercuei/dev-new-dmabuf-api Paul Cercueil (6): dma-buf: Add dma_buf_{begin,end}_access() dma-buf: udmabuf: Implement .{begin,end}_access usb: gadget: Support already-mapped DMA SGs usb: gadget: functionfs: Factorize wait-for-endpoint code usb: gadget: functionfs: Add DMABUF import interface Documentation: usb: Document FunctionFS DMABUF API Documentation/usb/functionfs.rst | 36 ++ drivers/dma-buf/dma-buf.c | 66 ++++ drivers/dma-buf/udmabuf.c | 27 ++ drivers/usb/gadget/Kconfig | 1 + drivers/usb/gadget/function/f_fs.c | 502 ++++++++++++++++++++++++++-- drivers/usb/gadget/udc/core.c | 7 +- include/linux/dma-buf.h | 37 ++ include/linux/usb/gadget.h | 2 + include/uapi/linux/usb/functionfs.h | 41 +++ 9 files changed, 698 insertions(+), 21 deletions(-) -- 2.43.0

1 year, 2 months

Re: [PATCH] mm/cma: Drop cma_get_name()

by Andrew Morton

On Tue, 6 Feb 2024 09:45:18 +0530 Anshuman Khandual <anshuman.khandual(a)arm.com> wrote: > cma_get_name() just returns cma->name without any additional transformation > unlike other helpers such as cma_get_base() and cma_get_size(). This helper > is not worth the additional indirection, and can be dropped after replacing > directly with cma->name in the sole caller __add_cma_heap(). drivers/dma-buf/heaps/cma_heap.c: In function '__add_cma_heap': drivers/dma-buf/heaps/cma_heap.c:379:28: error: invalid use of undefined type 'struct cma' 379 | exp_info.name = cma->name; | ^~ Fixing this would require moving the `struct cma' definition into cma.h. I don't think that's worthwhile.

1 year, 2 months

[PATCH v3 00/11] Add mediate-drm secure flow for SVP

by Jason-JH.Lin

From: Jason-jh Lin <jason-jh.lin(a)mediatek.corp-partner.google.com> Memory Definitions: secure memory - Memory allocated in the TEE (Trusted Execution Environment) which is inaccessible in the REE (Rich Execution Environment, i.e. linux kernel/userspace). secure handle - Integer value which acts as reference to 'secure memory'. Used in communication between TEE and REE to reference 'secure memory'. secure buffer - 'secure memory' that is used to store decrypted, compressed video or for other general purposes in the TEE. secure surface - 'secure memory' that is used to store graphic buffers. Memory Usage in SVP: The overall flow of SVP starts with encrypted video coming in from an outside source into the REE. The REE will then allocate a 'secure buffer' and send the corresponding 'secure handle' along with the encrypted, compressed video data to the TEE. The TEE will then decrypt the video and store the result in the 'secure buffer'. The REE will then allocate a 'secure surface'. The REE will pass the 'secure handles' for both the 'secure buffer' and 'secure surface' into the TEE for video decoding. The video decoder HW will then decode the contents of the 'secure buffer' and place the result in the 'secure surface'. The REE will then attach the 'secure surface' to the overlay plane for rendering of the video. Everything relating to ensuring security of the actual contents of the 'secure buffer' and 'secure surface' is out of scope for the REE and is the responsibility of the TEE. DRM driver handles allocation of gem objects that are backed by a 'secure surface' and for displaying a 'secure surface' on the overlay plane. This introduces a new flag for object creation called DRM_MTK_GEM_CREATE_ENCRYPTED which indicates it should be a 'secure surface'. All changes here are in MediaTek specific code. --- TODO: 1) Remove get sec larb port interface in ddp_comp, ovl and ovl_adaptor. 2) Verify instruction for enabling/disabling dapc and larb port in TEE drop the sec_engine flags in normal world and. 3) Move DISP_REG_OVL_SECURE setting to secure world for mtk_disp_ovl.c. 4) Change the parameter register address in mtk_ddp_sec_write() from "u32 addr" to "struct cmdq_client_reg *cmdq_reg". 5) Implement setting mmsys routing table in the secure world series. --- Based on 5 series and 1 patch: [1] v3 dma-buf: heaps: Add MediaTek secure heap - https://patchwork.kernel.org/project/linux-mediatek/list/?series=809023 [2] v3 add driver to support secure video decoder - https://patchwork.kernel.org/project/linux-mediatek/list/?series=807308 [3] v4 soc: mediatek: Add register definitions for GCE - https://patchwork.kernel.org/project/linux-mediatek/patch/20231212121957.19… [4] v2 Add CMDQ driver support for mt8188 - https://patchwork.kernel.org/project/linux-mediatek/list/?series=810302 [5] Add mediatek,gce-events definition to mediatek,gce-mailbox bindings - https://patchwork.kernel.org/project/linux-mediatek/list/?series=810938 [6] v3 Add CMDQ secure driver for SVP - https://patchwork.kernel.org/project/linux-mediatek/list/?series=812379 --- Change in v3: 1. fix kerneldoc problems 2. fix typo in title and commit message 3. adjust naming for secure variable 4. add the missing part for is_suecure plane implementation 5. use BIT_ULL macro to replace bit shifting 6. move modification of ovl_adaptor part to the correct patch 7. add TODO list in commit message 8. add commit message for using share memory to store execute count Change in v2: 1. remove the DRIVER_RDNDER flag for mtk_drm_ioctl 2. move cmdq_insert_backup_cookie into client driver 3. move secure gce node define from mt8195-cherry.dtsi to mt8195.dtsi --- CK Hu (1): drm/mediatek: Add interface to allocate MediaTek GEM buffer. Jason-JH.Lin (10): drm/mediatek/uapi: Add DRM_MTK_GEM_CREATE_ENCRYPTED flag drm/mediatek: Add secure buffer control flow to mtk_drm_gem drm/mediatek: Add secure identify flag and funcution to mtk_drm_plane drm/mediatek: Add mtk_ddp_sec_write to config secure buffer info drm/mediatek: Add get_sec_port interface to mtk_ddp_comp drm/mediatek: Add secure layer config support for ovl drm/mediatek: Add secure layer config support for ovl_adaptor drm/mediatek: Add secure flow support to mediatek-drm drm/mediatek: Add cmdq_insert_backup_cookie before secure pkt finalize arm64: dts: mt8195: Add secure mbox settings for vdosys arch/arm64/boot/dts/mediatek/mt8195.dtsi | 6 +- drivers/gpu/drm/mediatek/mtk_disp_drv.h | 3 + drivers/gpu/drm/mediatek/mtk_disp_ovl.c | 31 +- .../gpu/drm/mediatek/mtk_disp_ovl_adaptor.c | 15 + drivers/gpu/drm/mediatek/mtk_drm_crtc.c | 274 +++++++++++++++++- drivers/gpu/drm/mediatek/mtk_drm_crtc.h | 1 + drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c | 30 ++ drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h | 14 + drivers/gpu/drm/mediatek/mtk_drm_drv.c | 13 + drivers/gpu/drm/mediatek/mtk_drm_gem.c | 122 ++++++++ drivers/gpu/drm/mediatek/mtk_drm_gem.h | 16 + drivers/gpu/drm/mediatek/mtk_drm_plane.c | 26 ++ drivers/gpu/drm/mediatek/mtk_drm_plane.h | 2 + drivers/gpu/drm/mediatek/mtk_mdp_rdma.c | 11 +- drivers/gpu/drm/mediatek/mtk_mdp_rdma.h | 2 + include/uapi/drm/mediatek_drm.h | 59 ++++ 16 files changed, 607 insertions(+), 18 deletions(-) create mode 100644 include/uapi/drm/mediatek_drm.h -- 2.18.0

1 year, 2 months

[PATCH] dma-buf: heaps: Don't track CMA dma-buf pages under RssFile

by T.J. Mercier

DMA buffers allocated from the CMA dma-buf heap get counted under RssFile for processes that map them and trigger page faults. In addition to the incorrect accounting reported to userspace, reclaim behavior was influenced by the MM_FILEPAGES counter until linux 6.8, but this memory is not reclaimable. [1] Change the CMA dma-buf heap to set VM_PFNMAP on the VMA so MM does not poke at the memory managed by this dma-buf heap, and use vmf_insert_pfn to correct the RSS accounting. The system dma-buf heap does not suffer from this issue since remap_pfn_range is used during the mmap of the buffer, which also sets VM_PFNMAP on the VMA. [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/m… Fixes: b61614ec318a ("dma-buf: heaps: Add CMA heap to dmabuf heaps") Signed-off-by: T.J. Mercier <tjmercier(a)google.com> --- drivers/dma-buf/heaps/cma_heap.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c index ee899f8e6721..4a63567e93ba 100644 --- a/drivers/dma-buf/heaps/cma_heap.c +++ b/drivers/dma-buf/heaps/cma_heap.c @@ -168,10 +168,7 @@ static vm_fault_t cma_heap_vm_fault(struct vm_fault *vmf) if (vmf->pgoff > buffer->pagecount) return VM_FAULT_SIGBUS; - vmf->page = buffer->pages[vmf->pgoff]; - get_page(vmf->page); - - return 0; + return vmf_insert_pfn(vma, vmf->address, page_to_pfn(buffer->pages[vmf->pgoff])); } static const struct vm_operations_struct dma_heap_vm_ops = { @@ -185,6 +182,8 @@ static int cma_heap_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma) if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0) return -EINVAL; + vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP); + vma->vm_ops = &dma_heap_vm_ops; vma->vm_private_data = buffer; -- 2.43.0.381.gb435a96ce8-goog

1 year, 2 months

[PATCH v6 0/6] iio: new DMABUF based API, v6

by Paul Cercueil

Hi Jonathan, This is the v6 of my patchset that introduces a new interface based on DMABUF objects. The code was updated quite a bit, using the feedback on the list for this patchset but also the feedback I received on the FunctionFS patchset that I'm working on upstreaming in parallel [1] where the DMABUF handling code is very similar. See below for the full changelog. I decided to drop the scope-based memory management for dma_buf and I hope you are OK with that. Christian wants the patch(es) to support scope-based memory management in dma-buf as a separate patchset; once it's in, I will gladly send a follow-up patch to use __free() where it makes sense. For performance numbers, I'll point you to the cover letter for my v5 patchset [2]. This patchset was based on next-20240129. Cheers, -Paul [1] https://lore.kernel.org/all/20230322092118.9213-1-paul@crapouillou.net/ [2] https://lore.kernel.org/linux-iio/219abc43b4fdd4a13b307ed2efaa0e6869e68e3f.… --- Changelog: * [2/6]: - Use new prototype for axi_dmac_alloc_desc() as it changed upstream * [3/6]: - Remove dead code in iio_dma_resv_lock() - Fix non-block actually blocking - Cache dma_buf_attachment instead of mapping/unmapping it for every transfer - Return -EINVAL instead of IIO_IOCTL_UNHANDLED for unknown ioctl - Make .block_enqueue() callback take a dma_fence pointer, which will be passed to iio_buffer_signal_dmabuf_done() instead of the dma_buf_attachment; and remove the backpointer from the priv structure to the dma_fence. - Use dma_fence_begin/end_signalling in the dma_fence critical sections - Unref dma_fence and dma_buf_attachment in worker, because they might try to lock the dma_resv, which would deadlock. - Add buffer ops to lock/unlock the queue. This is motivated by the fact that once the dma_fence has been installed, we cannot lock anything anymore - so the queue must be locked before the dma_fence is installed. - Use 'long retl' variable to handle the return value of dma_resv_wait_timeout() - Protect dmabufs list access with a mutex - Rework iio_buffer_find_attachment() to use the internal dmabufs list, instead of messing with dmabufs private data. - Add an atomically-increasing sequence number for fences * [4/6]: - Update iio_dma_buffer_enqueue_dmabuf() to take a dma_fence pointer - Pass that dma_fence pointer along to iio_buffer_signal_dmabuf_done() - Add iio_dma_buffer_lock_queue() / iio_dma_buffer_unlock_queue() - Do not lock the queue in iio_dma_buffer_enqueue_dmabuf(). The caller will ensure that it has been locked already. - Replace "int += bool;" by "if (bool) int++;" - Use dma_fence_begin/end_signalling in the dma_fence critical sections - Use one "num_dmabufs" fields instead of one "num_blocks" and one "num_fileio_blocks". Make it an atomic_t, which makes it possible to decrement it atomically in iio_buffer_block_release() without having to lock the queue mutex; and in turn, it means that we don't need to use iio_buffer_block_put_atomic() everywhere to avoid locking the queue mutex twice. - Use cleanup.h guard(mutex) when possible - Explicitely list all states in the switch in iio_dma_can_enqueue_block() - Rename iio_dma_buffer_fileio_mode() to iio_dma_buffer_can_use_fileio(), and add a comment explaining why it cannot race vs. DMABUF. * [5/6]: - Populate .lock_queue / .unlock_queue callbacks - Switch to atomic memory allocations in .submit_queue, because of the dma_fence critical section - Make sure that the size of the scatterlist is enough --- Paul Cercueil (6): dmaengine: Add API function dmaengine_prep_slave_dma_vec() dmaengine: dma-axi-dmac: Implement device_prep_slave_dma_vec iio: core: Add new DMABUF interface infrastructure iio: buffer-dma: Enable support for DMABUFs iio: buffer-dmaengine: Support new DMABUF based userspace API Documentation: iio: Document high-speed DMABUF based API Documentation/iio/dmabuf_api.rst | 54 ++ Documentation/iio/index.rst | 2 + drivers/dma/dma-axi-dmac.c | 40 ++ drivers/iio/buffer/industrialio-buffer-dma.c | 181 ++++++- .../buffer/industrialio-buffer-dmaengine.c | 58 ++- drivers/iio/industrialio-buffer.c | 462 ++++++++++++++++++ include/linux/dmaengine.h | 25 + include/linux/iio/buffer-dma.h | 31 ++ include/linux/iio/buffer_impl.h | 33 ++ include/uapi/linux/iio/buffer.h | 22 + 10 files changed, 891 insertions(+), 17 deletions(-) create mode 100644 Documentation/iio/dmabuf_api.rst -- 2.43.0

1 year, 2 months

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