Linaro-mm-sig

linaro-mm-sig@lists.linaro.org

15 participants
3028 discussions

[PATCH 04/15] staging/android/ion: delete dma_buf->kmap/unmap implemenation

by Daniel Vetter

There's no callers in-tree anymore. For merging probably best to stuff this into drm-misc, since that's where the dma-buf heaps will land too. And the resulting conflict hopefully ensures that dma-buf heaps wont have a new ->kmap/unmap implemenation. Signed-off-by: Daniel Vetter <daniel.vetter(a)intel.com> Cc: Laura Abbott <labbott(a)redhat.com> Cc: Sumit Semwal <sumit.semwal(a)linaro.org> Cc: devel(a)driverdev.osuosl.org Cc: linaro-mm-sig(a)lists.linaro.org --- drivers/staging/android/ion/ion.c | 14 -------------- 1 file changed, 14 deletions(-) diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c index e6b1ca141b93..bb4ededc1150 100644 --- a/drivers/staging/android/ion/ion.c +++ b/drivers/staging/android/ion/ion.c @@ -274,18 +274,6 @@ static void ion_dma_buf_release(struct dma_buf *dmabuf) _ion_buffer_destroy(buffer); } -static void *ion_dma_buf_kmap(struct dma_buf *dmabuf, unsigned long offset) -{ - struct ion_buffer *buffer = dmabuf->priv; - - return buffer->vaddr + offset * PAGE_SIZE; -} - -static void ion_dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long offset, - void *ptr) -{ -} - static int ion_dma_buf_begin_cpu_access(struct dma_buf *dmabuf, enum dma_data_direction direction) { @@ -349,8 +337,6 @@ static const struct dma_buf_ops dma_buf_ops = { .detach = ion_dma_buf_detatch, .begin_cpu_access = ion_dma_buf_begin_cpu_access, .end_cpu_access = ion_dma_buf_end_cpu_access, - .map = ion_dma_buf_kmap, - .unmap = ion_dma_buf_kunmap, }; static int ion_alloc(size_t len, unsigned int heap_id_mask, unsigned int flags) -- 2.24.0

5 years, 10 months

[PATCH 09/15] dma-buf: Drop dma_buf_k(un)map

by Daniel Vetter

It's unused. 10 years ago, back when 32bit was still fairly common and trying to not exhaust vmalloc space sounded like a worthwhile goal, adding these to dma_buf made sense. Reality is that they simply never caught on, and nowadays everyone who needs plenty of buffers will run in 64bit mode anyway. Also update the docs in this area to adjust them to reality. The actual hooks in dma_buf_ops will be removed once all the implementations are gone. Signed-off-by: Daniel Vetter <daniel.vetter(a)intel.com> Cc: Sumit Semwal <sumit.semwal(a)linaro.org> Cc: linux-media(a)vger.kernel.org Cc: linaro-mm-sig(a)lists.linaro.org --- drivers/dma-buf/dma-buf.c | 63 ++------------------------------------- include/linux/dma-buf.h | 2 -- 2 files changed, 3 insertions(+), 62 deletions(-) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index d377b4ca66bf..97988ce1d2dc 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -880,29 +880,9 @@ EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment); * with calls to dma_buf_begin_cpu_access() and dma_buf_end_cpu_access() * access. * - * To support dma_buf objects residing in highmem cpu access is page-based - * using an api similar to kmap. Accessing a dma_buf is done in aligned chunks - * of PAGE_SIZE size. Before accessing a chunk it needs to be mapped, which - * returns a pointer in kernel virtual address space. Afterwards the chunk - * needs to be unmapped again. There is no limit on how often a given chunk - * can be mapped and unmapped, i.e. the importer does not need to call - * begin_cpu_access again before mapping the same chunk again. - * - * Interfaces:: - * void \*dma_buf_kmap(struct dma_buf \*, unsigned long); - * void dma_buf_kunmap(struct dma_buf \*, unsigned long, void \*); - * - * Implementing the functions is optional for exporters and for importers all - * the restrictions of using kmap apply. - * - * dma_buf kmap calls outside of the range specified in begin_cpu_access are - * undefined. If the range is not PAGE_SIZE aligned, kmap needs to succeed on - * the partial chunks at the beginning and end but may return stale or bogus - * data outside of the range (in these partial chunks). - * - * For some cases the overhead of kmap can be too high, a vmap interface - * is introduced. This interface should be used very carefully, as vmalloc - * space is a limited resources on many architectures. + * Since for most kernel internal dma-buf accesses need the entire buffer, a + * vmap interface is introduced. Note that on very old 32-bit architectures + * vmalloc space might be limited and result in vmap calls failing. * * Interfaces:: * void \*dma_buf_vmap(struct dma_buf \*dmabuf) @@ -1052,43 +1032,6 @@ int dma_buf_end_cpu_access(struct dma_buf *dmabuf, } EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access); -/** - * dma_buf_kmap - Map a page of the buffer object into kernel address space. The - * same restrictions as for kmap and friends apply. - * @dmabuf: [in] buffer to map page from. - * @page_num: [in] page in PAGE_SIZE units to map. - * - * This call must always succeed, any necessary preparations that might fail - * need to be done in begin_cpu_access. - */ -void *dma_buf_kmap(struct dma_buf *dmabuf, unsigned long page_num) -{ - WARN_ON(!dmabuf); - - if (!dmabuf->ops->map) - return NULL; - return dmabuf->ops->map(dmabuf, page_num); -} -EXPORT_SYMBOL_GPL(dma_buf_kmap); - -/** - * dma_buf_kunmap - Unmap a page obtained by dma_buf_kmap. - * @dmabuf: [in] buffer to unmap page from. - * @page_num: [in] page in PAGE_SIZE units to unmap. - * @vaddr: [in] kernel space pointer obtained from dma_buf_kmap. - * - * This call must always succeed. - */ -void dma_buf_kunmap(struct dma_buf *dmabuf, unsigned long page_num, - void *vaddr) -{ - WARN_ON(!dmabuf); - - if (dmabuf->ops->unmap) - dmabuf->ops->unmap(dmabuf, page_num, vaddr); -} -EXPORT_SYMBOL_GPL(dma_buf_kunmap); - /** * dma_buf_mmap - Setup up a userspace mmap with the given vma diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index af73f835c51c..7feb9c3805ae 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -464,8 +464,6 @@ int dma_buf_begin_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction dir); int dma_buf_end_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction dir); -void *dma_buf_kmap(struct dma_buf *, unsigned long); -void dma_buf_kunmap(struct dma_buf *, unsigned long, void *); int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *, unsigned long); -- 2.24.0

5 years, 10 months

[PATCH] dma-buf/sw-sync: Use unsigned type for value of sync_timeline

by Seung-Woo Kim

The value of sync_timeline is only incremented and all reference usage of it is unsigned. Use unsigned type for value of synctimeline. Signed-off-by: Seung-Woo Kim <sw0312.kim(a)samsung.com> --- drivers/dma-buf/sync_debug.h | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/drivers/dma-buf/sync_debug.h b/drivers/dma-buf/sync_debug.h index 6176e52..ff07f0b 100644 --- a/drivers/dma-buf/sync_debug.h +++ b/drivers/dma-buf/sync_debug.h @@ -36,7 +36,7 @@ struct sync_timeline { /* protected by lock */ u64 context; - int value; + unsigned int value; struct rb_root pt_tree; struct list_head pt_list; -- 1.7.4.1

5 years, 10 months

[bug report] dma-buf: heaps: Add heap helpers

by Dan Carpenter

Hello John Stultz, The patch 7b87ea704fd9: "dma-buf: heaps: Add heap helpers" from Oct 21, 2019, leads to the following static checker warning: drivers/dma-buf/heaps/heap-helpers.c:165 dma_heap_vm_fault() warn: uncapped user index 'buffer->pages[vmf->pgoff]' drivers/dma-buf/heaps/heap-helpers.c 160 static vm_fault_t dma_heap_vm_fault(struct vm_fault *vmf) 161 { 162 struct vm_area_struct *vma = vmf->vma; 163 struct heap_helper_buffer *buffer = vma->vm_private_data; 164 165 vmf->page = buffer->pages[vmf->pgoff]; ^^^^^^^^^^ Smatch for some reason thinks this needs to be checked. Smatch also gets confused by these fault handlers and thinks there is some recursion involved... 166 get_page(vmf->page); 167 168 return 0; 169 } 170 171 static const struct vm_operations_struct dma_heap_vm_ops = { 172 .fault = dma_heap_vm_fault, 173 }; 174 regards, dan carpenter

5 years, 10 months

Re: [Linaro-mm-sig] [PATCH][next] dma-buf: heaps: remove redundant assignment to variable ret

by John Stultz

On Wed, Oct 30, 2019 at 8:45 AM Andrew F. Davis <afd(a)ti.com> wrote: > > On 10/30/19 11:02 AM, Colin King wrote: > > From: Colin Ian King <colin.king(a)canonical.com> > > > > The variable ret is being assigned with a value that is never > > read, it is being re-assigned the same value on the err0 exit > > path. The assignment is redundant and hence can be removed. > > > > Addresses-Coverity: ("Unused value") > > Fixes: 47a32f9c1226 ("dma-buf: heaps: Add system heap to dmabuf heaps") > > Signed-off-by: Colin Ian King <colin.king(a)canonical.com> > > --- > > > The root of the issue is that ret is not used in the error path, it > should be, I suggest this fix: > > > --- a/drivers/dma-buf/heaps/system_heap.c > > +++ b/drivers/dma-buf/heaps/system_heap.c > > @@ -98,7 +98,7 @@ static int system_heap_allocate(struct dma_heap *heap, > > err0: > > kfree(helper_buffer); > > > > - return -ENOMEM; > > + return ret; > > } Sounds good! If its ok I'll generate a commit crediting Colin for reporting the issue and Andrew for the fix and submit it to Sumit. Many thanks to you both! -john

5 years, 10 months

[PATCH] dma-buf: heaps: Fix redundant assignment to variable ret in system_heap.c

by John Stultz

Colin King reported a coverity error: The variable ret is being assigned with a value that is never read, it is being re-assigned the same value on the err0 exit path. The assignment is redundant and hence can be removed. He had a fix, but Andrew Davis suggested a better solution (actually returning ret), so this patch implements that fix. Cc: Colin King <colin.king(a)canonical.com> Cc: Sumit Semwal <sumit.semwal(a)linaro.org> Cc: Benjamin Gaignard <benjamin.gaignard(a)linaro.org> Cc: Liam Mark <lmark(a)codeaurora.org> Cc: Laura Abbott <labbott(a)redhat.com> Cc: Brian Starkey <brian.starkey(a)arm.com> Cc: Andrew F. Davis <afd(a)ti.com> Cc: dri-devel(a)lists.freedesktop.org Cc: linaro-mm-sig(a)lists.linaro.org Cc: kernel-janitors(a)vger.kernel.org Addresses-Coverity: ("Unused value") Fixes: 47a32f9c1226 ("dma-buf: heaps: Add system heap to dmabuf heaps") Reported-by: Colin Ian King <colin.king(a)canonical.com> Suggested-by: Andrew F. Davis <afd(a)ti.com> Signed-off-by: John Stultz <john.stultz(a)linaro.org> --- drivers/dma-buf/heaps/system_heap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c index 455782efbb32..9a56393e40b4 100644 --- a/drivers/dma-buf/heaps/system_heap.c +++ b/drivers/dma-buf/heaps/system_heap.c @@ -98,7 +98,7 @@ static int system_heap_allocate(struct dma_heap *heap, err0: kfree(helper_buffer); - return -ENOMEM; + return ret; } static const struct dma_heap_ops system_heap_ops = { -- 2.17.1

5 years, 10 months

[PATCH] dma-buf: Fix a warning message in dma_heap_buffer_destroy()

by Dan Carpenter

The first argument of WARN() is a condition so this will just print the function name instead of the whole warning message. Fixes: 7b87ea704fd9 ("dma-buf: heaps: Add heap helpers") Signed-off-by: Dan Carpenter <dan.carpenter(a)oracle.com> --- drivers/dma-buf/heaps/heap-helpers.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/dma-buf/heaps/heap-helpers.c b/drivers/dma-buf/heaps/heap-helpers.c index 750bef4e902d..a31684c0d5b2 100644 --- a/drivers/dma-buf/heaps/heap-helpers.c +++ b/drivers/dma-buf/heaps/heap-helpers.c @@ -52,7 +52,7 @@ static void *dma_heap_map_kernel(struct heap_helper_buffer *buffer) static void dma_heap_buffer_destroy(struct heap_helper_buffer *buffer) { if (buffer->vmap_cnt > 0) { - WARN("%s: buffer still mapped in the kernel\n", __func__); + WARN(1, "%s: buffer still mapped in the kernel\n", __func__); vunmap(buffer->vaddr); } -- 2.20.1

5 years, 10 months

[PATCH][next] dma-buf: heaps: remove redundant assignment to variable ret

by Colin King

From: Colin Ian King <colin.king(a)canonical.com> The variable ret is being assigned with a value that is never read, it is being re-assigned the same value on the err0 exit path. The assignment is redundant and hence can be removed. Addresses-Coverity: ("Unused value") Fixes: 47a32f9c1226 ("dma-buf: heaps: Add system heap to dmabuf heaps") Signed-off-by: Colin Ian King <colin.king(a)canonical.com> --- drivers/dma-buf/heaps/system_heap.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c index 455782efbb32..817a1667bd57 100644 --- a/drivers/dma-buf/heaps/system_heap.c +++ b/drivers/dma-buf/heaps/system_heap.c @@ -55,10 +55,8 @@ static int system_heap_allocate(struct dma_heap *heap, helper_buffer->pages = kmalloc_array(helper_buffer->pagecount, sizeof(*helper_buffer->pages), GFP_KERNEL); - if (!helper_buffer->pages) { - ret = -ENOMEM; + if (!helper_buffer->pages) goto err0; - } for (pg = 0; pg < helper_buffer->pagecount; pg++) { /* -- 2.20.1

5 years, 10 months

[PATCH 1/4] dma-buf: change DMA-buf locking convention v2

by Christian König

This patch is a stripped down version of the locking changes necessary to support dynamic DMA-buf handling. It adds a dynamic flag for both importers as well as exporters so that drivers can choose if they want the reservation object locked or unlocked during mapping of attachments. For compatibility between drivers we cache the DMA-buf mapping during attaching an importer as soon as exporter/importer disagree on the dynamic handling. This change has gone through a lengthy discussion on dri-devel and other mailing lists with at least 3-4 different attempts and dead-ends until we settled on this solution. Please refer to the mailing lists archives for full background on the history of this change. v2: cleanup set_name merge, improve kerneldoc Signed-off-by: Christian König <christian.koenig(a)amd.com> --- drivers/dma-buf/dma-buf.c | 102 +++++++++++++++++++++++++++++++++----- include/linux/dma-buf.h | 57 +++++++++++++++++++-- 2 files changed, 143 insertions(+), 16 deletions(-) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 433d91d710e4..753be84b5fd6 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -45,10 +45,10 @@ static char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen) size_t ret = 0; dmabuf = dentry->d_fsdata; - mutex_lock(&dmabuf->lock); + dma_resv_lock(dmabuf->resv, NULL); if (dmabuf->name) ret = strlcpy(name, dmabuf->name, DMA_BUF_NAME_LEN); - mutex_unlock(&dmabuf->lock); + dma_resv_unlock(dmabuf->resv); return dynamic_dname(dentry, buffer, buflen, "/%s:%s", dentry->d_name.name, ret > 0 ? name : ""); @@ -334,7 +334,7 @@ static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf) if (IS_ERR(name)) return PTR_ERR(name); - mutex_lock(&dmabuf->lock); + dma_resv_lock(dmabuf->resv, NULL); if (!list_empty(&dmabuf->attachments)) { ret = -EBUSY; kfree(name); @@ -344,7 +344,7 @@ static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf) dmabuf->name = name; out_unlock: - mutex_unlock(&dmabuf->lock); + dma_resv_unlock(dmabuf->resv); return ret; } @@ -403,10 +403,10 @@ static void dma_buf_show_fdinfo(struct seq_file *m, struct file *file) /* Don't count the temporary reference taken inside procfs seq_show */ seq_printf(m, "count:\t%ld\n", file_count(dmabuf->file) - 1); seq_printf(m, "exp_name:\t%s\n", dmabuf->exp_name); - mutex_lock(&dmabuf->lock); + dma_resv_lock(dmabuf->resv, NULL); if (dmabuf->name) seq_printf(m, "name:\t%s\n", dmabuf->name); - mutex_unlock(&dmabuf->lock); + dma_resv_unlock(dmabuf->resv); } static const struct file_operations dma_buf_fops = { @@ -525,6 +525,10 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info) return ERR_PTR(-EINVAL); } + if (WARN_ON(exp_info->ops->cache_sgt_mapping && + exp_info->ops->dynamic_mapping)) + return ERR_PTR(-EINVAL); + if (!try_module_get(exp_info->owner)) return ERR_PTR(-ENOENT); @@ -645,10 +649,11 @@ void dma_buf_put(struct dma_buf *dmabuf) EXPORT_SYMBOL_GPL(dma_buf_put); /** - * dma_buf_attach - Add the device to dma_buf's attachments list; optionally, + * dma_buf_dynamic_attach - Add the device to dma_buf's attachments list; optionally, * calls attach() of dma_buf_ops to allow device-specific attach functionality - * @dmabuf: [in] buffer to attach device to. - * @dev: [in] device to be attached. + * @dmabuf: [in] buffer to attach device to. + * @dev: [in] device to be attached. + * @dynamic_mapping: [in] calling convention for map/unmap * * Returns struct dma_buf_attachment pointer for this attachment. Attachments * must be cleaned up by calling dma_buf_detach(). @@ -662,8 +667,9 @@ EXPORT_SYMBOL_GPL(dma_buf_put); * accessible to @dev, and cannot be moved to a more suitable place. This is * indicated with the error code -EBUSY. */ -struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, - struct device *dev) +struct dma_buf_attachment * +dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev, + bool dynamic_mapping) { struct dma_buf_attachment *attach; int ret; @@ -677,6 +683,7 @@ struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, attach->dev = dev; attach->dmabuf = dmabuf; + attach->dynamic_mapping = dynamic_mapping; mutex_lock(&dmabuf->lock); @@ -685,16 +692,64 @@ struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, if (ret) goto err_attach; } + dma_resv_lock(dmabuf->resv, NULL); list_add(&attach->node, &dmabuf->attachments); + dma_resv_unlock(dmabuf->resv); mutex_unlock(&dmabuf->lock); + /* When either the importer or the exporter can't handle dynamic + * mappings we cache the mapping here to avoid issues with the + * reservation object lock. + */ + if (dma_buf_attachment_is_dynamic(attach) != + dma_buf_is_dynamic(dmabuf)) { + struct sg_table *sgt; + + if (dma_buf_is_dynamic(attach->dmabuf)) + dma_resv_lock(attach->dmabuf->resv, NULL); + + sgt = dmabuf->ops->map_dma_buf(attach, DMA_BIDIRECTIONAL); + if (!sgt) + sgt = ERR_PTR(-ENOMEM); + if (IS_ERR(sgt)) { + ret = PTR_ERR(sgt); + goto err_unlock; + } + if (dma_buf_is_dynamic(attach->dmabuf)) + dma_resv_unlock(attach->dmabuf->resv); + attach->sgt = sgt; + attach->dir = DMA_BIDIRECTIONAL; + } + return attach; err_attach: kfree(attach); mutex_unlock(&dmabuf->lock); return ERR_PTR(ret); + +err_unlock: + if (dma_buf_is_dynamic(attach->dmabuf)) + dma_resv_unlock(attach->dmabuf->resv); + + dma_buf_detach(dmabuf, attach); + return ERR_PTR(ret); +} +EXPORT_SYMBOL_GPL(dma_buf_dynamic_attach); + +/** + * dma_buf_attach - Wrapper for dma_buf_dynamic_attach + * @dmabuf: [in] buffer to attach device to. + * @dev: [in] device to be attached. + * + * Wrapper to call dma_buf_dynamic_attach() for drivers which still use a static + * mapping. + */ +struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, + struct device *dev) +{ + return dma_buf_dynamic_attach(dmabuf, dev, false); } EXPORT_SYMBOL_GPL(dma_buf_attach); @@ -711,11 +766,20 @@ void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach) if (WARN_ON(!dmabuf || !attach)) return; - if (attach->sgt) + if (attach->sgt) { + if (dma_buf_is_dynamic(attach->dmabuf)) + dma_resv_lock(attach->dmabuf->resv, NULL); + dmabuf->ops->unmap_dma_buf(attach, attach->sgt, attach->dir); + if (dma_buf_is_dynamic(attach->dmabuf)) + dma_resv_unlock(attach->dmabuf->resv); + } + mutex_lock(&dmabuf->lock); + dma_resv_lock(dmabuf->resv, NULL); list_del(&attach->node); + dma_resv_unlock(dmabuf->resv); if (dmabuf->ops->detach) dmabuf->ops->detach(dmabuf, attach); @@ -749,6 +813,9 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach, if (WARN_ON(!attach || !attach->dmabuf)) return ERR_PTR(-EINVAL); + if (dma_buf_attachment_is_dynamic(attach)) + dma_resv_assert_held(attach->dmabuf->resv); + if (attach->sgt) { /* * Two mappings with different directions for the same @@ -761,6 +828,9 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach, return attach->sgt; } + if (dma_buf_is_dynamic(attach->dmabuf)) + dma_resv_assert_held(attach->dmabuf->resv); + sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction); if (!sg_table) sg_table = ERR_PTR(-ENOMEM); @@ -793,9 +863,15 @@ void dma_buf_unmap_attachment(struct dma_buf_attachment *attach, if (WARN_ON(!attach || !attach->dmabuf || !sg_table)) return; + if (dma_buf_attachment_is_dynamic(attach)) + dma_resv_assert_held(attach->dmabuf->resv); + if (attach->sgt == sg_table) return; + if (dma_buf_is_dynamic(attach->dmabuf)) + dma_resv_assert_held(attach->dmabuf->resv); + attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction); } EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment); @@ -1219,10 +1295,12 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused) seq_puts(s, "\tAttached Devices:\n"); attach_count = 0; + dma_resv_lock(buf_obj->resv, NULL); list_for_each_entry(attach_obj, &buf_obj->attachments, node) { seq_printf(s, "\t%s\n", dev_name(attach_obj->dev)); attach_count++; } + dma_resv_unlock(buf_obj->resv); seq_printf(s, "Total %d devices attached\n\n", attach_count); diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index ec212cb27fdc..bcc0f4d0b678 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -42,6 +42,18 @@ struct dma_buf_ops { */ bool cache_sgt_mapping; + /** + * @dynamic_mapping: + * + * If true the framework makes sure that the map/unmap_dma_buf + * callbacks are always called with the dma_resv object locked. + * + * If false the framework makes ure that the map/unmap_dma_buf + * callbacks are always called without the dma_resv object locked. + * Mutual exclusive with @cache_sgt_mapping. + */ + bool dynamic_mapping; + /** * @attach: * @@ -109,6 +121,9 @@ struct dma_buf_ops { * any other kind of sharing that the exporter might wish to make * available to buffer-users. * + * This is always called with the dmabuf->resv object locked when + * the dynamic_mapping flag is true. + * * Returns: * * A &sg_table scatter list of or the backing storage of the DMA buffer, @@ -267,7 +282,8 @@ struct dma_buf_ops { * struct dma_buf - shared buffer object * @size: size of the buffer * @file: file pointer used for sharing buffers across, and for refcounting. - * @attachments: list of dma_buf_attachment that denotes all devices attached. + * @attachments: list of dma_buf_attachment that denotes all devices attached, + * protected by dma_resv lock. * @ops: dma_buf_ops associated with this buffer object. * @lock: used internally to serialize list manipulation, attach/detach and * vmap/unmap, and accesses to name @@ -323,10 +339,12 @@ struct dma_buf { * struct dma_buf_attachment - holds device-buffer attachment data * @dmabuf: buffer for this attachment. * @dev: device attached to the buffer. - * @node: list of dma_buf_attachment. + * @node: list of dma_buf_attachment, protected by dma_resv lock of the dmabuf. * @sgt: cached mapping. * @dir: direction of cached mapping. * @priv: exporter specific attachment data. + * @dynamic_mapping: true if dma_buf_map/unmap_attachment() is called with the + * dma_resv lock held. * * This structure holds the attachment information between the dma_buf buffer * and its user device(s). The list contains one attachment struct per device @@ -343,6 +361,7 @@ struct dma_buf_attachment { struct list_head node; struct sg_table *sgt; enum dma_data_direction dir; + bool dynamic_mapping; void *priv; }; @@ -394,10 +413,39 @@ static inline void get_dma_buf(struct dma_buf *dmabuf) get_file(dmabuf->file); } +/** + * dma_buf_is_dynamic - check if a DMA-buf uses dynamic mappings. + * @dmabuf: the DMA-buf to check + * + * Returns true if a DMA-buf exporter wants to be called with the dma_resv + * locked, false if it doesn't wants to be called with the lock held. + */ +static inline bool dma_buf_is_dynamic(struct dma_buf *dmabuf) +{ + return dmabuf->ops->dynamic_mapping; +} + +/** + * dma_buf_attachment_is_dynamic - check if a DMA-buf attachment uses dynamic + * mappinsg + * @attach: the DMA-buf attachment to check + * + * Returns true if a DMA-buf importer wants to call the map/unmap functions with + * the dma_resv lock held. + */ +static inline bool +dma_buf_attachment_is_dynamic(struct dma_buf_attachment *attach) +{ + return attach->dynamic_mapping; +} + struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, - struct device *dev); + struct device *dev); +struct dma_buf_attachment * +dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev, + bool dynamic_mapping); void dma_buf_detach(struct dma_buf *dmabuf, - struct dma_buf_attachment *dmabuf_attach); + struct dma_buf_attachment *attach); struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info); @@ -409,6 +457,7 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *, enum dma_data_direction); void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *, enum dma_data_direction); +void dma_buf_move_notify(struct dma_buf *dma_buf); int dma_buf_begin_cpu_access(struct dma_buf *dma_buf, enum dma_data_direction dir); int dma_buf_end_cpu_access(struct dma_buf *dma_buf, -- 2.17.1

5 years, 10 months

Dynamic DMA-buf locking changes

by Christian König

Hi everyone, since upstreaming the full dynamic DMA-buf changes turned out more problematic than previously thought I've reverted back to individual patches and separated out only the locking changes. So this patch does NOT contain any new callbacks for pinning/unpinning and move notification, but only the locking changes necessary. As previously discussed when the framework detects that the locking semantics between exporter and importer are different it just falls back to using a cached sgt created during attach time. While separating the patch set I've most likely stumbled over the problem why this previously raised some lockdep warning with i915, it turned out to be just a might_lock() at the wrong place. Please review and/or comment, Christian.

5 years, 11 months

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