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Release 4.14 drivers/dma-buf/dma-buf.c

Directory: drivers/dma-buf
/*
 * Framework for buffer objects that can be shared across devices/subsystems.
 *
 * Copyright(C) 2011 Linaro Limited. All rights reserved.
 * Author: Sumit Semwal <sumit.semwal@ti.com>
 *
 * Many thanks to linaro-mm-sig list, and specially
 * Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and
 * Daniel Vetter <daniel@ffwll.ch> for their support in creation and
 * refining of this idea.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/dma-buf.h>
#include <linux/dma-fence.h>
#include <linux/anon_inodes.h>
#include <linux/export.h>
#include <linux/debugfs.h>
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/poll.h>
#include <linux/reservation.h>
#include <linux/mm.h>

#include <uapi/linux/dma-buf.h>

static inline int is_dma_buf_file(struct file *);


struct dma_buf_list {
	
struct list_head head;
	
struct mutex lock;
};


static struct dma_buf_list db_list;


static int dma_buf_release(struct inode *inode, struct file *file) { struct dma_buf *dmabuf; if (!is_dma_buf_file(file)) return -EINVAL; dmabuf = file->private_data; BUG_ON(dmabuf->vmapping_counter); /* * Any fences that a dma-buf poll can wait on should be signaled * before releasing dma-buf. This is the responsibility of each * driver that uses the reservation objects. * * If you hit this BUG() it means someone dropped their ref to the * dma-buf while still having pending operation to the buffer. */ BUG_ON(dmabuf->cb_shared.active || dmabuf->cb_excl.active); dmabuf->ops->release(dmabuf); mutex_lock(&db_list.lock); list_del(&dmabuf->list_node); mutex_unlock(&db_list.lock); if (dmabuf->resv == (struct reservation_object *)&dmabuf[1]) reservation_object_fini(dmabuf->resv); module_put(dmabuf->owner); kfree(dmabuf); return 0; }

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Sumit Semwal8764.93%350.00%
Maarten Lankhorst4029.85%233.33%
Daniel Vetter75.22%116.67%
Total134100.00%6100.00%


static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma) { struct dma_buf *dmabuf; if (!is_dma_buf_file(file)) return -EINVAL; dmabuf = file->private_data; /* check for overflowing the buffer's size */ if (vma->vm_pgoff + vma_pages(vma) > dmabuf->size >> PAGE_SHIFT) return -EINVAL; return dmabuf->ops->mmap(dmabuf, vma); }

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Daniel Vetter7095.89%150.00%
Muhammad Falak R Wani34.11%150.00%
Total73100.00%2100.00%


static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence) { struct dma_buf *dmabuf; loff_t base; if (!is_dma_buf_file(file)) return -EBADF; dmabuf = file->private_data; /* only support discovering the end of the buffer, but also allow SEEK_SET to maintain the idiomatic SEEK_END(0), SEEK_CUR(0) pattern */ if (whence == SEEK_END) base = dmabuf->size; else if (whence == SEEK_SET) base = 0; else return -EINVAL; if (offset != 0) return -EINVAL; return base + offset; }

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Christopher James Halse Rogers87100.00%1100.00%
Total87100.00%1100.00%

/** * DOC: fence polling * * To support cross-device and cross-driver synchronization of buffer access * implicit fences (represented internally in the kernel with &struct fence) can * be attached to a &dma_buf. The glue for that and a few related things are * provided in the &reservation_object structure. * * Userspace can query the state of these implicitly tracked fences using poll() * and related system calls: * * - Checking for POLLIN, i.e. read access, can be use to query the state of the * most recent write or exclusive fence. * * - Checking for POLLOUT, i.e. write access, can be used to query the state of * all attached fences, shared and exclusive ones. * * Note that this only signals the completion of the respective fences, i.e. the * DMA transfers are complete. Cache flushing and any other necessary * preparations before CPU access can begin still need to happen. */
static void dma_buf_poll_cb(struct dma_fence *fence, struct dma_fence_cb *cb) { struct dma_buf_poll_cb_t *dcb = (struct dma_buf_poll_cb_t *)cb; unsigned long flags; spin_lock_irqsave(&dcb->poll->lock, flags); wake_up_locked_poll(dcb->poll, dcb->active); dcb->active = 0; spin_unlock_irqrestore(&dcb->poll->lock, flags); }

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Maarten Lankhorst7197.26%150.00%
Chris Wilson22.74%150.00%
Total73100.00%2100.00%


static unsigned int dma_buf_poll(struct file *file, poll_table *poll) { struct dma_buf *dmabuf; struct reservation_object *resv; struct reservation_object_list *fobj; struct dma_fence *fence_excl; unsigned long events; unsigned shared_count, seq; dmabuf = file->private_data; if (!dmabuf || !dmabuf->resv) return POLLERR; resv = dmabuf->resv; poll_wait(file, &dmabuf->poll, poll); events = poll_requested_events(poll) & (POLLIN | POLLOUT); if (!events) return 0; retry: seq = read_seqcount_begin(&resv->seq); rcu_read_lock(); fobj = rcu_dereference(resv->fence); if (fobj) shared_count = fobj->shared_count; else shared_count = 0; fence_excl = rcu_dereference(resv->fence_excl); if (read_seqcount_retry(&resv->seq, seq)) { rcu_read_unlock(); goto retry; } if (fence_excl && (!(events & POLLOUT) || shared_count == 0)) { struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_excl; unsigned long pevents = POLLIN; if (shared_count == 0) pevents |= POLLOUT; spin_lock_irq(&dmabuf->poll.lock); if (dcb->active) { dcb->active |= pevents; events &= ~pevents; } else dcb->active = pevents; spin_unlock_irq(&dmabuf->poll.lock); if (events & pevents) { if (!dma_fence_get_rcu(fence_excl)) { /* force a recheck */ events &= ~pevents; dma_buf_poll_cb(NULL, &dcb->cb); } else if (!dma_fence_add_callback(fence_excl, &dcb->cb, dma_buf_poll_cb)) { events &= ~pevents; dma_fence_put(fence_excl); } else { /* * No callback queued, wake up any additional * waiters. */ dma_fence_put(fence_excl); dma_buf_poll_cb(NULL, &dcb->cb); } } } if ((events & POLLOUT) && shared_count > 0) { struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_shared; int i; /* Only queue a new callback if no event has fired yet */ spin_lock_irq(&dmabuf->poll.lock); if (dcb->active) events &= ~POLLOUT; else dcb->active = POLLOUT; spin_unlock_irq(&dmabuf->poll.lock); if (!(events & POLLOUT)) goto out; for (i = 0; i < shared_count; ++i) { struct dma_fence *fence = rcu_dereference(fobj->shared[i]); if (!dma_fence_get_rcu(fence)) { /* * fence refcount dropped to zero, this means * that fobj has been freed * * call dma_buf_poll_cb and force a recheck! */ events &= ~POLLOUT; dma_buf_poll_cb(NULL, &dcb->cb); break; } if (!dma_fence_add_callback(fence, &dcb->cb, dma_buf_poll_cb)) { dma_fence_put(fence); events &= ~POLLOUT; break; } dma_fence_put(fence); } /* No callback queued, wake up any additional waiters. */ if (i == shared_count) dma_buf_poll_cb(NULL, &dcb->cb); } out: rcu_read_unlock(); return events; }

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Maarten Lankhorst52698.13%375.00%
Chris Wilson101.87%125.00%
Total536100.00%4100.00%


static long dma_buf_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct dma_buf *dmabuf; struct dma_buf_sync sync; enum dma_data_direction direction; int ret; dmabuf = file->private_data; switch (cmd) { case DMA_BUF_IOCTL_SYNC: if (copy_from_user(&sync, (void __user *) arg, sizeof(sync))) return -EFAULT; if (sync.flags & ~DMA_BUF_SYNC_VALID_FLAGS_MASK) return -EINVAL; switch (sync.flags & DMA_BUF_SYNC_RW) { case DMA_BUF_SYNC_READ: direction = DMA_FROM_DEVICE; break; case DMA_BUF_SYNC_WRITE: direction = DMA_TO_DEVICE; break; case DMA_BUF_SYNC_RW: direction = DMA_BIDIRECTIONAL; break; default: return -EINVAL; } if (sync.flags & DMA_BUF_SYNC_END) ret = dma_buf_end_cpu_access(dmabuf, direction); else ret = dma_buf_begin_cpu_access(dmabuf, direction); return ret; default: return -ENOTTY; } }

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Daniel Vetter15395.03%150.00%
Chris Wilson84.97%150.00%
Total161100.00%2100.00%

static const struct file_operations dma_buf_fops = { .release = dma_buf_release, .mmap = dma_buf_mmap_internal, .llseek = dma_buf_llseek, .poll = dma_buf_poll, .unlocked_ioctl = dma_buf_ioctl, #ifdef CONFIG_COMPAT .compat_ioctl = dma_buf_ioctl, #endif }; /* * is_dma_buf_file - Check if struct file* is associated with dma_buf */
static inline int is_dma_buf_file(struct file *file) { return file->f_op == &dma_buf_fops; }

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Sumit Semwal20100.00%1100.00%
Total20100.00%1100.00%

/** * DOC: dma buf device access * * For device DMA access to a shared DMA buffer the usual sequence of operations * is fairly simple: * * 1. The exporter defines his exporter instance using * DEFINE_DMA_BUF_EXPORT_INFO() and calls dma_buf_export() to wrap a private * buffer object into a &dma_buf. It then exports that &dma_buf to userspace * as a file descriptor by calling dma_buf_fd(). * * 2. Userspace passes this file-descriptors to all drivers it wants this buffer * to share with: First the filedescriptor is converted to a &dma_buf using * dma_buf_get(). The the buffer is attached to the device using * dma_buf_attach(). * * Up to this stage the exporter is still free to migrate or reallocate the * backing storage. * * 3. Once the buffer is attached to all devices userspace can inniate DMA * access to the shared buffer. In the kernel this is done by calling * dma_buf_map_attachment() and dma_buf_unmap_attachment(). * * 4. Once a driver is done with a shared buffer it needs to call * dma_buf_detach() (after cleaning up any mappings) and then release the * reference acquired with dma_buf_get by calling dma_buf_put(). * * For the detailed semantics exporters are expected to implement see * &dma_buf_ops. */ /** * dma_buf_export - Creates a new dma_buf, and associates an anon file * with this buffer, so it can be exported. * Also connect the allocator specific data and ops to the buffer. * Additionally, provide a name string for exporter; useful in debugging. * * @exp_info: [in] holds all the export related information provided * by the exporter. see &struct dma_buf_export_info * for further details. * * Returns, on success, a newly created dma_buf object, which wraps the * supplied private data and operations for dma_buf_ops. On either missing * ops, or error in allocating struct dma_buf, will return negative error. * * For most cases the easiest way to create @exp_info is through the * %DEFINE_DMA_BUF_EXPORT_INFO macro. */
struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info) { struct dma_buf *dmabuf; struct reservation_object *resv = exp_info->resv; struct file *file; size_t alloc_size = sizeof(struct dma_buf); int ret; if (!exp_info->resv) alloc_size += sizeof(struct reservation_object); else /* prevent &dma_buf[1] == dma_buf->resv */ alloc_size += 1; if (WARN_ON(!exp_info->priv || !exp_info->ops || !exp_info->ops->map_dma_buf || !exp_info->ops->unmap_dma_buf || !exp_info->ops->release || !exp_info->ops->map_atomic || !exp_info->ops->map || !exp_info->ops->mmap)) { return ERR_PTR(-EINVAL); } if (!try_module_get(exp_info->owner)) return ERR_PTR(-ENOENT); dmabuf = kzalloc(alloc_size, GFP_KERNEL); if (!dmabuf) { ret = -ENOMEM; goto err_module; } dmabuf->priv = exp_info->priv; dmabuf->ops = exp_info->ops; dmabuf->size = exp_info->size; dmabuf->exp_name = exp_info->exp_name; dmabuf->owner = exp_info->owner; init_waitqueue_head(&dmabuf->poll); dmabuf->cb_excl.poll = dmabuf->cb_shared.poll = &dmabuf->poll; dmabuf->cb_excl.active = dmabuf->cb_shared.active = 0; if (!resv) { resv = (struct reservation_object *)&dmabuf[1]; reservation_object_init(resv); } dmabuf->resv = resv; file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, exp_info->flags); if (IS_ERR(file)) { ret = PTR_ERR(file); goto err_dmabuf; } file->f_mode |= FMODE_LSEEK; dmabuf->file = file; mutex_init(&dmabuf->lock); INIT_LIST_HEAD(&dmabuf->attachments); mutex_lock(&db_list.lock); list_add(&dmabuf->list_node, &db_list.head); mutex_unlock(&db_list.lock); return dmabuf; err_dmabuf: kfree(dmabuf); err_module: module_put(exp_info->owner); return ERR_PTR(ret); }

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Sumit Semwal22857.14%535.71%
Maarten Lankhorst9924.81%214.29%
Chris Wilson389.52%17.14%
Daniel Vetter133.26%214.29%
Tuomas Tynkkynen123.01%17.14%
Christopher James Halse Rogers61.50%17.14%
Logan Gunthorpe20.50%17.14%
Laurent Pinchart10.25%17.14%
Total399100.00%14100.00%

EXPORT_SYMBOL_GPL(dma_buf_export); /** * dma_buf_fd - returns a file descriptor for the given dma_buf * @dmabuf: [in] pointer to dma_buf for which fd is required. * @flags: [in] flags to give to fd * * On success, returns an associated 'fd'. Else, returns error. */
int dma_buf_fd(struct dma_buf *dmabuf, int flags) { int fd; if (!dmabuf || !dmabuf->file) return -EINVAL; fd = get_unused_fd_flags(flags); if (fd < 0) return fd; fd_install(fd, dmabuf->file); return fd; }

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Sumit Semwal4882.76%133.33%
Dave Airlie712.07%133.33%
Borislav Petkov35.17%133.33%
Total58100.00%3100.00%

EXPORT_SYMBOL_GPL(dma_buf_fd); /** * dma_buf_get - returns the dma_buf structure related to an fd * @fd: [in] fd associated with the dma_buf to be returned * * On success, returns the dma_buf structure associated with an fd; uses * file's refcounting done by fget to increase refcount. returns ERR_PTR * otherwise. */
struct dma_buf *dma_buf_get(int fd) { struct file *file; file = fget(fd); if (!file) return ERR_PTR(-EBADF); if (!is_dma_buf_file(file)) { fput(file); return ERR_PTR(-EINVAL); } return file->private_data; }

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Sumit Semwal61100.00%1100.00%
Total61100.00%1100.00%

EXPORT_SYMBOL_GPL(dma_buf_get); /** * dma_buf_put - decreases refcount of the buffer * @dmabuf: [in] buffer to reduce refcount of * * Uses file's refcounting done implicitly by fput(). * * If, as a result of this call, the refcount becomes 0, the 'release' file * operation related to this fd is called. It calls &dma_buf_ops.release vfunc * in turn, and frees the memory allocated for dmabuf when exported. */
void dma_buf_put(struct dma_buf *dmabuf) { if (WARN_ON(!dmabuf || !dmabuf->file)) return; fput(dmabuf->file); }

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Sumit Semwal31100.00%1100.00%
Total31100.00%1100.00%

EXPORT_SYMBOL_GPL(dma_buf_put); /** * dma_buf_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. * * Returns struct dma_buf_attachment pointer for this attachment. Attachments * must be cleaned up by calling dma_buf_detach(). * * Returns: * * A pointer to newly created &dma_buf_attachment on success, or a negative * error code wrapped into a pointer on failure. * * Note that this can fail if the backing storage of @dmabuf is in a place not * 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 *attach; int ret; if (WARN_ON(!dmabuf || !dev)) return ERR_PTR(-EINVAL); attach = kzalloc(sizeof(*attach), GFP_KERNEL); if (!attach) return ERR_PTR(-ENOMEM); attach->dev = dev; attach->dmabuf = dmabuf; mutex_lock(&dmabuf->lock); if (dmabuf->ops->attach) { ret = dmabuf->ops->attach(dmabuf, dev, attach); if (ret) goto err_attach; } list_add(&attach->node, &dmabuf->attachments); mutex_unlock(&dmabuf->lock); return attach; err_attach: kfree(attach); mutex_unlock(&dmabuf->lock); return ERR_PTR(ret); }

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Sumit Semwal14789.09%120.00%
Laurent Pinchart159.09%240.00%
SF Markus Elfring31.82%240.00%
Total165100.00%5100.00%

EXPORT_SYMBOL_GPL(dma_buf_attach); /** * dma_buf_detach - Remove the given attachment from dmabuf's attachments list; * optionally calls detach() of dma_buf_ops for device-specific detach * @dmabuf: [in] buffer to detach from. * @attach: [in] attachment to be detached; is free'd after this call. * * Clean up a device attachment obtained by calling dma_buf_attach(). */
void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach) { if (WARN_ON(!dmabuf || !attach)) return; mutex_lock(&dmabuf->lock); list_del(&attach->node); if (dmabuf->ops->detach) dmabuf->ops->detach(dmabuf, attach); mutex_unlock(&dmabuf->lock); kfree(attach); }

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Sumit Semwal75100.00%1100.00%
Total75100.00%1100.00%

EXPORT_SYMBOL_GPL(dma_buf_detach); /** * dma_buf_map_attachment - Returns the scatterlist table of the attachment; * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the * dma_buf_ops. * @attach: [in] attachment whose scatterlist is to be returned * @direction: [in] direction of DMA transfer * * Returns sg_table containing the scatterlist to be returned; returns ERR_PTR * on error. May return -EINTR if it is interrupted by a signal. * * A mapping must be unmapped again using dma_buf_map_attachment(). Note that * the underlying backing storage is pinned for as long as a mapping exists, * therefore users/importers should not hold onto a mapping for undue amounts of * time. */
struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach, enum dma_data_direction direction) { struct sg_table *sg_table = ERR_PTR(-EINVAL); might_sleep(); if (WARN_ON(!attach || !attach->dmabuf)) return ERR_PTR(-EINVAL); sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction); if (!sg_table) sg_table = ERR_PTR(-ENOMEM); return sg_table; }

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Sumit Semwal6883.95%150.00%
Colin Cross1316.05%150.00%
Total81100.00%2100.00%

EXPORT_SYMBOL_GPL(dma_buf_map_attachment); /** * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of * dma_buf_ops. * @attach: [in] attachment to unmap buffer from * @sg_table: [in] scatterlist info of the buffer to unmap * @direction: [in] direction of DMA transfer * * This unmaps a DMA mapping for @attached obtained by dma_buf_map_attachment(). */
void dma_buf_unmap_attachment(struct dma_buf_attachment *attach, struct sg_table *sg_table, enum dma_data_direction direction) { might_sleep(); if (WARN_ON(!attach || !attach->dmabuf || !sg_table)) return; attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction); }

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Sumit Semwal5194.44%266.67%
Rob Clark35.56%133.33%
Total54100.00%3100.00%

EXPORT_SYMBOL_GPL(dma_buf_unmap_attachment); /** * DOC: cpu access * * There are mutliple reasons for supporting CPU access to a dma buffer object: * * - Fallback operations in the kernel, for example when a device is connected * over USB and the kernel needs to shuffle the data around first before * sending it away. Cache coherency is handled by braketing any transactions * 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 \*); * * There are also atomic variants of these interfaces. Like for kmap they * facilitate non-blocking fast-paths. Neither the importer nor the exporter * (in the callback) is allowed to block when using these. * * Interfaces:: * void \*dma_buf_kmap_atomic(struct dma_buf \*, unsigned long); * void dma_buf_kunmap_atomic(struct dma_buf \*, unsigned long, void \*); * * For importers all the restrictions of using kmap apply, like the limited * supply of kmap_atomic slots. Hence an importer shall only hold onto at * max 2 atomic dma_buf kmaps at the same time (in any given process context). * * 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). * * Note that these calls need to always succeed. The exporter needs to * complete any preparations that might fail in begin_cpu_access. * * 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. * * Interfaces:: * void \*dma_buf_vmap(struct dma_buf \*dmabuf) * void dma_buf_vunmap(struct dma_buf \*dmabuf, void \*vaddr) * * The vmap call can fail if there is no vmap support in the exporter, or if * it runs out of vmalloc space. Fallback to kmap should be implemented. Note * that the dma-buf layer keeps a reference count for all vmap access and * calls down into the exporter's vmap function only when no vmapping exists, * and only unmaps it once. Protection against concurrent vmap/vunmap calls is * provided by taking the dma_buf->lock mutex. * * - For full compatibility on the importer side with existing userspace * interfaces, which might already support mmap'ing buffers. This is needed in * many processing pipelines (e.g. feeding a software rendered image into a * hardware pipeline, thumbnail creation, snapshots, ...). Also, Android's ION * framework already supported this and for DMA buffer file descriptors to * replace ION buffers mmap support was needed. * * There is no special interfaces, userspace simply calls mmap on the dma-buf * fd. But like for CPU access there's a need to braket the actual access, * which is handled by the ioctl (DMA_BUF_IOCTL_SYNC). Note that * DMA_BUF_IOCTL_SYNC can fail with -EAGAIN or -EINTR, in which case it must * be restarted. * * Some systems might need some sort of cache coherency management e.g. when * CPU and GPU domains are being accessed through dma-buf at the same time. * To circumvent this problem there are begin/end coherency markers, that * forward directly to existing dma-buf device drivers vfunc hooks. Userspace * can make use of those markers through the DMA_BUF_IOCTL_SYNC ioctl. The * sequence would be used like following: * * - mmap dma-buf fd * - for each drawing/upload cycle in CPU 1. SYNC_START ioctl, 2. read/write * to mmap area 3. SYNC_END ioctl. This can be repeated as often as you * want (with the new data being consumed by say the GPU or the scanout * device) * - munmap once you don't need the buffer any more * * For correctness and optimal performance, it is always required to use * SYNC_START and SYNC_END before and after, respectively, when accessing the * mapped address. Userspace cannot rely on coherent access, even when there * are systems where it just works without calling these ioctls. * * - And as a CPU fallback in userspace processing pipelines. * * Similar to the motivation for kernel cpu access it is again important that * the userspace code of a given importing subsystem can use the same * interfaces with a imported dma-buf buffer object as with a native buffer * object. This is especially important for drm where the userspace part of * contemporary OpenGL, X, and other drivers is huge, and reworking them to * use a different way to mmap a buffer rather invasive. * * The assumption in the current dma-buf interfaces is that redirecting the * initial mmap is all that's needed. A survey of some of the existing * subsystems shows that no driver seems to do any nefarious thing like * syncing up with outstanding asynchronous processing on the device or * allocating special resources at fault time. So hopefully this is good * enough, since adding interfaces to intercept pagefaults and allow pte * shootdowns would increase the complexity quite a bit. * * Interface:: * int dma_buf_mmap(struct dma_buf \*, struct vm_area_struct \*, * unsigned long); * * If the importing subsystem simply provides a special-purpose mmap call to * set up a mapping in userspace, calling do_mmap with dma_buf->file will * equally achieve that for a dma-buf object. */
static int __dma_buf_begin_cpu_access(struct dma_buf *dmabuf, enum dma_data_direction direction) { bool write = (direction == DMA_BIDIRECTIONAL || direction == DMA_TO_DEVICE); struct reservation_object *resv = dmabuf->resv; long ret; /* Wait on any implicit rendering fences */ ret = reservation_object_wait_timeout_rcu(resv, write, true, MAX_SCHEDULE_TIMEOUT); if (ret < 0) return ret; return 0; }

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Chris Wilson66100.00%1100.00%
Total66100.00%1100.00%

/** * dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the * cpu in the kernel context. Calls begin_cpu_access to allow exporter-specific * preparations. Coherency is only guaranteed in the specified range for the * specified access direction. * @dmabuf: [in] buffer to prepare cpu access for. * @direction: [in] length of range for cpu access. * * After the cpu access is complete the caller should call * dma_buf_end_cpu_access(). Only when cpu access is braketed by both calls is * it guaranteed to be coherent with other DMA access. * * Can return negative error values, returns 0 on success. */
int dma_buf_begin_cpu_access(struct dma_buf *dmabuf, enum dma_data_direction direction) { int ret = 0; if (WARN_ON(!dmabuf)) return -EINVAL; if (dmabuf->ops->begin_cpu_access) ret = dmabuf->ops->begin_cpu_access(dmabuf, direction); /* Ensure that all fences are waited upon - but we first allow * the native handler the chance to do so more efficiently if it * chooses. A double invocation here will be reasonably cheap no-op. */ if (ret == 0) ret = __dma_buf_begin_cpu_access(dmabuf, direction); return ret; }

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Daniel Vetter5577.46%150.00%
Chris Wilson1622.54%150.00%
Total71100.00%2100.00%

EXPORT_SYMBOL_GPL(dma_buf_begin_cpu_access); /** * dma_buf_end_cpu_access - Must be called after accessing a dma_buf from the * cpu in the kernel context. Calls end_cpu_access to allow exporter-specific * actions. Coherency is only guaranteed in the specified range for the * specified access direction. * @dmabuf: [in] buffer to complete cpu access for. * @direction: [in] length of range for cpu access. * * This terminates CPU access started with dma_buf_begin_cpu_access(). * * Can return negative error values, returns 0 on success. */
int dma_buf_end_cpu_access(struct dma_buf *dmabuf, enum dma_data_direction direction) { int ret = 0; WARN_ON(!dmabuf); if (dmabuf->ops->end_cpu_access) ret = dmabuf->ops->end_cpu_access(dmabuf, direction); return ret; }

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Daniel Vetter3877.55%150.00%
Chris Wilson1122.45%150.00%
Total49100.00%2100.00%

EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access); /** * dma_buf_kmap_atomic - Map a page of the buffer object into kernel address * space. The same restrictions as for kmap_atomic 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_atomic(struct dma_buf *dmabuf, unsigned long page_num) { WARN_ON(!dmabuf); return dmabuf->ops->map_atomic(dmabuf, page_num); }

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Daniel Vetter3296.97%150.00%
Logan Gunthorpe13.03%150.00%
Total33100.00%2100.00%

EXPORT_SYMBOL_GPL(dma_buf_kmap_atomic); /** * dma_buf_kunmap_atomic - Unmap a page obtained by dma_buf_kmap_atomic. * @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_atomic. * * This call must always succeed. */
void dma_buf_kunmap_atomic(struct dma_buf *dmabuf, unsigned long page_num, void *vaddr) { WARN_ON(!dmabuf); if (dmabuf->ops->unmap_atomic) dmabuf->ops->unmap_atomic(dmabuf, page_num, vaddr); }

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Daniel Vetter4395.56%150.00%
Logan Gunthorpe24.44%150.00%
Total45100.00%2100.00%

EXPORT_SYMBOL_GPL(dma_buf_kunmap_atomic); /** * 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); return dmabuf->ops->map(dmabuf, page_num); }

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Daniel Vetter3296.97%150.00%
Logan Gunthorpe13.03%150.00%
Total33100.00%2100.00%

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); }

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Daniel Vetter4395.56%150.00%
Logan Gunthorpe24.44%150.00%
Total45100.00%2100.00%

EXPORT_SYMBOL_GPL(dma_buf_kunmap); /** * dma_buf_mmap - Setup up a userspace mmap with the given vma * @dmabuf: [in] buffer that should back the vma * @vma: [in] vma for the mmap * @pgoff: [in] offset in pages where this mmap should start within the * dma-buf buffer. * * This function adjusts the passed in vma so that it points at the file of the * dma_buf operation. It also adjusts the starting pgoff and does bounds * checking on the size of the vma. Then it calls the exporters mmap function to * set up the mapping. * * Can return negative error values, returns 0 on success. */
int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma, unsigned long pgoff) { struct file *oldfile; int ret; if (WARN_ON(!dmabuf || !vma)) return -EINVAL; /* check for offset overflow */ if (pgoff + vma_pages(vma) < pgoff) return -EOVERFLOW; /* check for overflowing the buffer's size */ if (pgoff + vma_pages(vma) > dmabuf->size >> PAGE_SHIFT) return -EINVAL; /* readjust the vma */ get_file(dmabuf->file); oldfile = vma->vm_file; vma->vm_file = dmabuf->file; vma->vm_pgoff = pgoff; ret = dmabuf->ops->mmap(dmabuf, vma); if (ret) { /* restore old parameters on failure */ vma->vm_file = oldfile; fput(dmabuf->file); } else { if (oldfile) fput(oldfile); } return ret; }

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Daniel Vetter9360.39%125.00%
John Sheu5334.42%125.00%
Muhammad Falak R Wani63.90%125.00%
Al Viro21.30%125.00%
Total154100.00%4100.00%

EXPORT_SYMBOL_GPL(dma_buf_mmap); /** * dma_buf_vmap - Create virtual mapping for the buffer object into kernel * address space. Same restrictions as for vmap and friends apply. * @dmabuf: [in] buffer to vmap * * This call may fail due to lack of virtual mapping address space. * These calls are optional in drivers. The intended use for them * is for mapping objects linear in kernel space for high use objects. * Please attempt to use kmap/kunmap before thinking about these interfaces. * * Returns NULL on error. */
void *dma_buf_vmap(struct dma_buf *dmabuf) { void *ptr; if (WARN_ON(!dmabuf)) return NULL; if (!dmabuf->ops->vmap) return NULL; mutex_lock(&dmabuf->lock); if (dmabuf->vmapping_counter) { dmabuf->vmapping_counter++; BUG_ON(!dmabuf->vmap_ptr); ptr = dmabuf->vmap_ptr; goto out_unlock; } BUG_ON(dmabuf->vmap_ptr); ptr = dmabuf->ops->vmap(dmabuf); if (WARN_ON_ONCE(IS_ERR(ptr))) ptr = NULL; if (!ptr) goto out_unlock; dmabuf->vmap_ptr = ptr; dmabuf->vmapping_counter = 1; out_unlock: mutex_unlock(&dmabuf->lock); return ptr; }

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Daniel Vetter8761.70%133.33%
Dave Airlie4129.08%133.33%
Colin Cross139.22%133.33%
Total141100.00%3100.00%

EXPORT_SYMBOL_GPL(dma_buf_vmap); /** * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap. * @dmabuf: [in] buffer to vunmap * @vaddr: [in] vmap to vunmap */
void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr) { if (WARN_ON(!dmabuf)) return; BUG_ON(!dmabuf->vmap_ptr); BUG_ON(dmabuf->vmapping_counter == 0); BUG_ON(dmabuf->vmap_ptr != vaddr); mutex_lock(&dmabuf->lock); if (--dmabuf->vmapping_counter == 0) { if (dmabuf->ops->vunmap) dmabuf->ops->vunmap(dmabuf, vaddr); dmabuf->vmap_ptr = NULL; } mutex_unlock(&dmabuf->lock); }

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Daniel Vetter5958.42%150.00%
Dave Airlie4241.58%150.00%
Total101100.00%2100.00%

EXPORT_SYMBOL_GPL(dma_buf_vunmap); #ifdef CONFIG_DEBUG_FS
static int dma_buf_debug_show(