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Diffstat (limited to 'drivers/dma-buf/dma-fence.c')
| -rw-r--r-- | drivers/dma-buf/dma-fence.c | 965 |
1 files changed, 965 insertions, 0 deletions
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c new file mode 100644 index 000000000..eef4786aa --- /dev/null +++ b/drivers/dma-buf/dma-fence.c @@ -0,0 +1,965 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Fence mechanism for dma-buf and to allow for asynchronous dma access + * + * Copyright (C) 2012 Canonical Ltd + * Copyright (C) 2012 Texas Instruments + * + * Authors: + * Rob Clark <robdclark@gmail.com> + * Maarten Lankhorst <maarten.lankhorst@canonical.com> + */ + +#include <linux/slab.h> +#include <linux/export.h> +#include <linux/atomic.h> +#include <linux/dma-fence.h> +#include <linux/sched/signal.h> +#include <linux/seq_file.h> + +#define CREATE_TRACE_POINTS +#include <trace/events/dma_fence.h> + +EXPORT_TRACEPOINT_SYMBOL(dma_fence_emit); +EXPORT_TRACEPOINT_SYMBOL(dma_fence_enable_signal); +EXPORT_TRACEPOINT_SYMBOL(dma_fence_signaled); + +static DEFINE_SPINLOCK(dma_fence_stub_lock); +static struct dma_fence dma_fence_stub; + +/* + * fence context counter: each execution context should have its own + * fence context, this allows checking if fences belong to the same + * context or not. One device can have multiple separate contexts, + * and they're used if some engine can run independently of another. + */ +static atomic64_t dma_fence_context_counter = ATOMIC64_INIT(1); + +/** + * 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 dma_resv through the + * &dma_buf.resv pointer. + */ + +/** + * DOC: fence cross-driver contract + * + * Since &dma_fence provide a cross driver contract, all drivers must follow the + * same rules: + * + * * Fences must complete in a reasonable time. Fences which represent kernels + * and shaders submitted by userspace, which could run forever, must be backed + * up by timeout and gpu hang recovery code. Minimally that code must prevent + * further command submission and force complete all in-flight fences, e.g. + * when the driver or hardware do not support gpu reset, or if the gpu reset + * failed for some reason. Ideally the driver supports gpu recovery which only + * affects the offending userspace context, and no other userspace + * submissions. + * + * * Drivers may have different ideas of what completion within a reasonable + * time means. Some hang recovery code uses a fixed timeout, others a mix + * between observing forward progress and increasingly strict timeouts. + * Drivers should not try to second guess timeout handling of fences from + * other drivers. + * + * * To ensure there's no deadlocks of dma_fence_wait() against other locks + * drivers should annotate all code required to reach dma_fence_signal(), + * which completes the fences, with dma_fence_begin_signalling() and + * dma_fence_end_signalling(). + * + * * Drivers are allowed to call dma_fence_wait() while holding dma_resv_lock(). + * This means any code required for fence completion cannot acquire a + * &dma_resv lock. Note that this also pulls in the entire established + * locking hierarchy around dma_resv_lock() and dma_resv_unlock(). + * + * * Drivers are allowed to call dma_fence_wait() from their &shrinker + * callbacks. This means any code required for fence completion cannot + * allocate memory with GFP_KERNEL. + * + * * Drivers are allowed to call dma_fence_wait() from their &mmu_notifier + * respectively &mmu_interval_notifier callbacks. This means any code required + * for fence completeion cannot allocate memory with GFP_NOFS or GFP_NOIO. + * Only GFP_ATOMIC is permissible, which might fail. + * + * Note that only GPU drivers have a reasonable excuse for both requiring + * &mmu_interval_notifier and &shrinker callbacks at the same time as having to + * track asynchronous compute work using &dma_fence. No driver outside of + * drivers/gpu should ever call dma_fence_wait() in such contexts. + */ + +static const char *dma_fence_stub_get_name(struct dma_fence *fence) +{ + return "stub"; +} + +static const struct dma_fence_ops dma_fence_stub_ops = { + .get_driver_name = dma_fence_stub_get_name, + .get_timeline_name = dma_fence_stub_get_name, +}; + +/** + * dma_fence_get_stub - return a signaled fence + * + * Return a stub fence which is already signaled. The fence's + * timestamp corresponds to the first time after boot this + * function is called. + */ +struct dma_fence *dma_fence_get_stub(void) +{ + spin_lock(&dma_fence_stub_lock); + if (!dma_fence_stub.ops) { + dma_fence_init(&dma_fence_stub, + &dma_fence_stub_ops, + &dma_fence_stub_lock, + 0, 0); + + set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, + &dma_fence_stub.flags); + + dma_fence_signal_locked(&dma_fence_stub); + } + spin_unlock(&dma_fence_stub_lock); + + return dma_fence_get(&dma_fence_stub); +} +EXPORT_SYMBOL(dma_fence_get_stub); + +/** + * dma_fence_allocate_private_stub - return a private, signaled fence + * @timestamp: timestamp when the fence was signaled + * + * Return a newly allocated and signaled stub fence. + */ +struct dma_fence *dma_fence_allocate_private_stub(ktime_t timestamp) +{ + struct dma_fence *fence; + + fence = kzalloc(sizeof(*fence), GFP_KERNEL); + if (fence == NULL) + return NULL; + + dma_fence_init(fence, + &dma_fence_stub_ops, + &dma_fence_stub_lock, + 0, 0); + + set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, + &fence->flags); + + dma_fence_signal_timestamp(fence, timestamp); + + return fence; +} +EXPORT_SYMBOL(dma_fence_allocate_private_stub); + +/** + * dma_fence_context_alloc - allocate an array of fence contexts + * @num: amount of contexts to allocate + * + * 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) +{ + WARN_ON(!num); + return atomic64_fetch_add(num, &dma_fence_context_counter); +} +EXPORT_SYMBOL(dma_fence_context_alloc); + +/** + * DOC: fence signalling annotation + * + * Proving correctness of all the kernel code around &dma_fence through code + * review and testing is tricky for a few reasons: + * + * * It is a cross-driver contract, and therefore all drivers must follow the + * same rules for lock nesting order, calling contexts for various functions + * and anything else significant for in-kernel interfaces. But it is also + * impossible to test all drivers in a single machine, hence brute-force N vs. + * N testing of all combinations is impossible. Even just limiting to the + * possible combinations is infeasible. + * + * * There is an enormous amount of driver code involved. For render drivers + * there's the tail of command submission, after fences are published, + * scheduler code, interrupt and workers to process job completion, + * and timeout, gpu reset and gpu hang recovery code. Plus for integration + * with core mm with have &mmu_notifier, respectively &mmu_interval_notifier, + * and &shrinker. For modesetting drivers there's the commit tail functions + * between when fences for an atomic modeset are published, and when the + * corresponding vblank completes, including any interrupt processing and + * related workers. Auditing all that code, across all drivers, is not + * feasible. + * + * * Due to how many other subsystems are involved and the locking hierarchies + * this pulls in there is extremely thin wiggle-room for driver-specific + * differences. &dma_fence interacts with almost all of the core memory + * handling through page fault handlers via &dma_resv, dma_resv_lock() and + * dma_resv_unlock(). On the other side it also interacts through all + * allocation sites through &mmu_notifier and &shrinker. + * + * Furthermore lockdep does not handle cross-release dependencies, which means + * any deadlocks between dma_fence_wait() and dma_fence_signal() can't be caught + * at runtime with some quick testing. The simplest example is one thread + * waiting on a &dma_fence while holding a lock:: + * + * lock(A); + * dma_fence_wait(B); + * unlock(A); + * + * while the other thread is stuck trying to acquire the same lock, which + * prevents it from signalling the fence the previous thread is stuck waiting + * on:: + * + * lock(A); + * unlock(A); + * dma_fence_signal(B); + * + * By manually annotating all code relevant to signalling a &dma_fence we can + * teach lockdep about these dependencies, which also helps with the validation + * headache since now lockdep can check all the rules for us:: + * + * cookie = dma_fence_begin_signalling(); + * lock(A); + * unlock(A); + * dma_fence_signal(B); + * dma_fence_end_signalling(cookie); + * + * For using dma_fence_begin_signalling() and dma_fence_end_signalling() to + * annotate critical sections the following rules need to be observed: + * + * * All code necessary to complete a &dma_fence must be annotated, from the + * point where a fence is accessible to other threads, to the point where + * dma_fence_signal() is called. Un-annotated code can contain deadlock issues, + * and due to the very strict rules and many corner cases it is infeasible to + * catch these just with review or normal stress testing. + * + * * &struct dma_resv deserves a special note, since the readers are only + * protected by rcu. This means the signalling critical section starts as soon + * as the new fences are installed, even before dma_resv_unlock() is called. + * + * * The only exception are fast paths and opportunistic signalling code, which + * calls dma_fence_signal() purely as an optimization, but is not required to + * guarantee completion of a &dma_fence. The usual example is a wait IOCTL + * which calls dma_fence_signal(), while the mandatory completion path goes + * through a hardware interrupt and possible job completion worker. + * + * * To aid composability of code, the annotations can be freely nested, as long + * as the overall locking hierarchy is consistent. The annotations also work + * both in interrupt and process context. Due to implementation details this + * requires that callers pass an opaque cookie from + * dma_fence_begin_signalling() to dma_fence_end_signalling(). + * + * * Validation against the cross driver contract is implemented by priming + * lockdep with the relevant hierarchy at boot-up. This means even just + * testing with a single device is enough to validate a driver, at least as + * far as deadlocks with dma_fence_wait() against dma_fence_signal() are + * concerned. + */ +#ifdef CONFIG_LOCKDEP +static struct lockdep_map dma_fence_lockdep_map = { + .name = "dma_fence_map" +}; + +/** + * dma_fence_begin_signalling - begin a critical DMA fence signalling section + * + * Drivers should use this to annotate the beginning of any code section + * required to eventually complete &dma_fence by calling dma_fence_signal(). + * + * The end of these critical sections are annotated with + * dma_fence_end_signalling(). + * + * Returns: + * + * Opaque cookie needed by the implementation, which needs to be passed to + * dma_fence_end_signalling(). + */ +bool dma_fence_begin_signalling(void) +{ + /* explicitly nesting ... */ + if (lock_is_held_type(&dma_fence_lockdep_map, 1)) + return true; + + /* rely on might_sleep check for soft/hardirq locks */ + if (in_atomic()) + return true; + + /* ... and non-recursive readlock */ + lock_acquire(&dma_fence_lockdep_map, 0, 0, 1, 1, NULL, _RET_IP_); + + return false; +} +EXPORT_SYMBOL(dma_fence_begin_signalling); + +/** + * dma_fence_end_signalling - end a critical DMA fence signalling section + * @cookie: opaque cookie from dma_fence_begin_signalling() + * + * Closes a critical section annotation opened by dma_fence_begin_signalling(). + */ +void dma_fence_end_signalling(bool cookie) +{ + if (cookie) + return; + + lock_release(&dma_fence_lockdep_map, _RET_IP_); +} +EXPORT_SYMBOL(dma_fence_end_signalling); + +void __dma_fence_might_wait(void) +{ + bool tmp; + + tmp = lock_is_held_type(&dma_fence_lockdep_map, 1); + if (tmp) + lock_release(&dma_fence_lockdep_map, _THIS_IP_); + lock_map_acquire(&dma_fence_lockdep_map); + lock_map_release(&dma_fence_lockdep_map); + if (tmp) + lock_acquire(&dma_fence_lockdep_map, 0, 0, 1, 1, NULL, _THIS_IP_); +} +#endif + + +/** + * dma_fence_signal_timestamp_locked - signal completion of a fence + * @fence: the fence to signal + * @timestamp: fence signal timestamp in kernel's CLOCK_MONOTONIC time domain + * + * 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 the unsignaled to the signaled state and not back, it will + * only be effective the first time. Set the timestamp provided as the fence + * signal timestamp. + * + * Unlike dma_fence_signal_timestamp(), this function must be called with + * &dma_fence.lock held. + * + * Returns 0 on success and a negative error value when @fence has been + * signalled already. + */ +int dma_fence_signal_timestamp_locked(struct dma_fence *fence, + ktime_t timestamp) +{ + struct dma_fence_cb *cur, *tmp; + struct list_head cb_list; + + lockdep_assert_held(fence->lock); + + if (unlikely(test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT, + &fence->flags))) + return -EINVAL; + + /* Stash the cb_list before replacing it with the timestamp */ + list_replace(&fence->cb_list, &cb_list); + + fence->timestamp = timestamp; + set_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags); + trace_dma_fence_signaled(fence); + + list_for_each_entry_safe(cur, tmp, &cb_list, node) { + INIT_LIST_HEAD(&cur->node); + cur->func(fence, cur); + } + + return 0; +} +EXPORT_SYMBOL(dma_fence_signal_timestamp_locked); + +/** + * dma_fence_signal_timestamp - signal completion of a fence + * @fence: the fence to signal + * @timestamp: fence signal timestamp in kernel's CLOCK_MONOTONIC time domain + * + * 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 the unsignaled to the signaled state and not back, it will + * only be effective the first time. Set the timestamp provided as the fence + * signal timestamp. + * + * Returns 0 on success and a negative error value when @fence has been + * signalled already. + */ +int dma_fence_signal_timestamp(struct dma_fence *fence, ktime_t timestamp) +{ + unsigned long flags; + int ret; + + if (!fence) + return -EINVAL; + + spin_lock_irqsave(fence->lock, flags); + ret = dma_fence_signal_timestamp_locked(fence, timestamp); + spin_unlock_irqrestore(fence->lock, flags); + + return ret; +} +EXPORT_SYMBOL(dma_fence_signal_timestamp); + +/** + * dma_fence_signal_locked - signal completion of a fence + * @fence: the fence to signal + * + * 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 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. + * + * Returns 0 on success and a negative error value when @fence has been + * signalled already. + */ +int dma_fence_signal_locked(struct dma_fence *fence) +{ + return dma_fence_signal_timestamp_locked(fence, ktime_get()); +} +EXPORT_SYMBOL(dma_fence_signal_locked); + +/** + * dma_fence_signal - signal completion of a fence + * @fence: the fence to signal + * + * 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 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) +{ + unsigned long flags; + int ret; + bool tmp; + + if (!fence) + return -EINVAL; + + tmp = dma_fence_begin_signalling(); + + spin_lock_irqsave(fence->lock, flags); + ret = dma_fence_signal_timestamp_locked(fence, ktime_get()); + spin_unlock_irqrestore(fence->lock, flags); + + dma_fence_end_signalling(tmp); + + return ret; +} +EXPORT_SYMBOL(dma_fence_signal); + +/** + * dma_fence_wait_timeout - sleep until the fence gets signaled + * or until timeout elapses + * @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 + * returned on custom implementations. + * + * Performs a synchronous wait on this fence. It is assumed the caller + * 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) +{ + signed long ret; + + if (WARN_ON(timeout < 0)) + return -EINVAL; + + might_sleep(); + + __dma_fence_might_wait(); + + dma_fence_enable_sw_signaling(fence); + + trace_dma_fence_wait_start(fence); + if (fence->ops->wait) + ret = fence->ops->wait(fence, intr, timeout); + else + ret = dma_fence_default_wait(fence, intr, timeout); + trace_dma_fence_wait_end(fence); + return ret; +} +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 = + container_of(kref, struct dma_fence, refcount); + + trace_dma_fence_destroy(fence); + + if (WARN(!list_empty(&fence->cb_list) && + !test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags), + "Fence %s:%s:%llx:%llx released with pending signals!\n", + fence->ops->get_driver_name(fence), + fence->ops->get_timeline_name(fence), + fence->context, fence->seqno)) { + unsigned long flags; + + /* + * Failed to signal before release, likely a refcounting issue. + * + * This should never happen, but if it does make sure that we + * don't leave chains dangling. We set the error flag first + * so that the callbacks know this signal is due to an error. + */ + spin_lock_irqsave(fence->lock, flags); + fence->error = -EDEADLK; + dma_fence_signal_locked(fence); + spin_unlock_irqrestore(fence->lock, flags); + } + + if (fence->ops->release) + fence->ops->release(fence); + else + dma_fence_free(fence); +} +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); +} +EXPORT_SYMBOL(dma_fence_free); + +static bool __dma_fence_enable_signaling(struct dma_fence *fence) +{ + bool was_set; + + lockdep_assert_held(fence->lock); + + was_set = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, + &fence->flags); + + if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) + return false; + + if (!was_set && fence->ops->enable_signaling) { + trace_dma_fence_enable_signal(fence); + + if (!fence->ops->enable_signaling(fence)) { + dma_fence_signal_locked(fence); + return false; + } + } + + return true; +} + +/** + * dma_fence_enable_sw_signaling - enable signaling on fence + * @fence: the fence to enable + * + * 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) +{ + unsigned long flags; + + spin_lock_irqsave(fence->lock, flags); + __dma_fence_enable_signaling(fence); + spin_unlock_irqrestore(fence->lock, flags); +} +EXPORT_SYMBOL(dma_fence_enable_sw_signaling); + +/** + * dma_fence_add_callback - add a callback to be called when the fence + * is signaled + * @fence: the fence to wait on + * @cb: the callback to register + * @func: the function to call + * + * Add a software callback to the fence. The caller should keep a reference to + * the fence. + * + * @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. + * + * If fence is already signaled, this function will return -ENOENT (and + * *not* call the callback). + * + * Note that the callback can be called from an atomic context or irq context. + * + * Returns 0 in case of success, -ENOENT if the fence is already signaled + * and -EINVAL in case of error. + */ +int dma_fence_add_callback(struct dma_fence *fence, struct dma_fence_cb *cb, + dma_fence_func_t func) +{ + unsigned long flags; + int ret = 0; + + if (WARN_ON(!fence || !func)) + return -EINVAL; + + if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) { + INIT_LIST_HEAD(&cb->node); + return -ENOENT; + } + + spin_lock_irqsave(fence->lock, flags); + + if (__dma_fence_enable_signaling(fence)) { + cb->func = func; + list_add_tail(&cb->node, &fence->cb_list); + } else { + INIT_LIST_HEAD(&cb->node); + ret = -ENOENT; + } + + spin_unlock_irqrestore(fence->lock, flags); + + return ret; +} +EXPORT_SYMBOL(dma_fence_add_callback); + +/** + * dma_fence_get_status - returns the status upon completion + * @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 + * details. + * + * Returns 0 if the fence has not yet been signaled, 1 if the fence has + * been signaled without an error condition, or a negative error code + * if the fence has been completed in err. + */ +int dma_fence_get_status(struct dma_fence *fence) +{ + unsigned long flags; + int status; + + spin_lock_irqsave(fence->lock, flags); + status = dma_fence_get_status_locked(fence); + spin_unlock_irqrestore(fence->lock, flags); + + return status; +} +EXPORT_SYMBOL(dma_fence_get_status); + +/** + * dma_fence_remove_callback - remove a callback from the signaling list + * @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 + * already been signaled. + * + * *WARNING*: + * Cancelling a callback should only be done if you really know what you're + * 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) +{ + unsigned long flags; + bool ret; + + spin_lock_irqsave(fence->lock, flags); + + ret = !list_empty(&cb->node); + if (ret) + list_del_init(&cb->node); + + spin_unlock_irqrestore(fence->lock, flags); + + return ret; +} +EXPORT_SYMBOL(dma_fence_remove_callback); + +struct default_wait_cb { + struct dma_fence_cb base; + struct task_struct *task; +}; + +static void +dma_fence_default_wait_cb(struct dma_fence *fence, struct dma_fence_cb *cb) +{ + struct default_wait_cb *wait = + container_of(cb, struct default_wait_cb, base); + + wake_up_state(wait->task, TASK_NORMAL); +} + +/** + * dma_fence_default_wait - default sleep until the fence gets signaled + * or until timeout elapses + * @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 + * returned if the fence is already signaled for consistency with other + * functions taking a jiffies timeout. + */ +signed long +dma_fence_default_wait(struct dma_fence *fence, bool intr, signed long timeout) +{ + struct default_wait_cb cb; + unsigned long flags; + signed long ret = timeout ? timeout : 1; + + spin_lock_irqsave(fence->lock, flags); + + if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) + goto out; + + if (intr && signal_pending(current)) { + ret = -ERESTARTSYS; + goto out; + } + + if (!timeout) { + ret = 0; + goto out; + } + + cb.base.func = dma_fence_default_wait_cb; + cb.task = current; + list_add(&cb.base.node, &fence->cb_list); + + while (!test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags) && ret > 0) { + if (intr) + __set_current_state(TASK_INTERRUPTIBLE); + else + __set_current_state(TASK_UNINTERRUPTIBLE); + spin_unlock_irqrestore(fence->lock, flags); + + ret = schedule_timeout(ret); + + spin_lock_irqsave(fence->lock, flags); + if (ret > 0 && intr && signal_pending(current)) + ret = -ERESTARTSYS; + } + + if (!list_empty(&cb.base.node)) + list_del(&cb.base.node); + __set_current_state(TASK_RUNNING); + +out: + spin_unlock_irqrestore(fence->lock, flags); + return ret; +} +EXPORT_SYMBOL(dma_fence_default_wait); + +static bool +dma_fence_test_signaled_any(struct dma_fence **fences, uint32_t count, + uint32_t *idx) +{ + int i; + + for (i = 0; i < count; ++i) { + struct dma_fence *fence = fences[i]; + if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags)) { + if (idx) + *idx = i; + return true; + } + } + return false; +} + +/** + * dma_fence_wait_any_timeout - sleep until any fence gets signaled + * or until timeout elapses + * @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 + * on success. + * + * 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, + bool intr, signed long timeout, uint32_t *idx) +{ + struct default_wait_cb *cb; + signed long ret = timeout; + unsigned i; + + if (WARN_ON(!fences || !count || timeout < 0)) + return -EINVAL; + + if (timeout == 0) { + for (i = 0; i < count; ++i) + if (dma_fence_is_signaled(fences[i])) { + if (idx) + *idx = i; + return 1; + } + + return 0; + } + + cb = kcalloc(count, sizeof(struct default_wait_cb), GFP_KERNEL); + if (cb == NULL) { + ret = -ENOMEM; + goto err_free_cb; + } + + for (i = 0; i < count; ++i) { + struct dma_fence *fence = fences[i]; + + cb[i].task = current; + if (dma_fence_add_callback(fence, &cb[i].base, + dma_fence_default_wait_cb)) { + /* This fence is already signaled */ + if (idx) + *idx = i; + goto fence_rm_cb; + } + } + + while (ret > 0) { + if (intr) + set_current_state(TASK_INTERRUPTIBLE); + else + set_current_state(TASK_UNINTERRUPTIBLE); + + if (dma_fence_test_signaled_any(fences, count, idx)) + break; + + ret = schedule_timeout(ret); + + if (ret > 0 && intr && signal_pending(current)) + ret = -ERESTARTSYS; + } + + __set_current_state(TASK_RUNNING); + +fence_rm_cb: + while (i-- > 0) + dma_fence_remove_callback(fences[i], &cb[i].base); + +err_free_cb: + kfree(cb); + + return ret; +} +EXPORT_SYMBOL(dma_fence_wait_any_timeout); + +/** + * dma_fence_describe - Dump fence describtion into seq_file + * @fence: the 6fence to describe + * @seq: the seq_file to put the textual description into + * + * Dump a textual description of the fence and it's state into the seq_file. + */ +void dma_fence_describe(struct dma_fence *fence, struct seq_file *seq) +{ + seq_printf(seq, "%s %s seq %llu %ssignalled\n", + fence->ops->get_driver_name(fence), + fence->ops->get_timeline_name(fence), fence->seqno, + dma_fence_is_signaled(fence) ? "" : "un"); +} +EXPORT_SYMBOL(dma_fence_describe); + +/** + * dma_fence_init - Initialize a custom fence. + * @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. + * + * context and seqno are used for easy comparison between fences, allowing + * 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, + spinlock_t *lock, u64 context, u64 seqno) +{ + BUG_ON(!lock); + BUG_ON(!ops || !ops->get_driver_name || !ops->get_timeline_name); + + kref_init(&fence->refcount); + fence->ops = ops; + INIT_LIST_HEAD(&fence->cb_list); + fence->lock = lock; + fence->context = context; + fence->seqno = seqno; + fence->flags = 0UL; + fence->error = 0; + + trace_dma_fence_init(fence); +} +EXPORT_SYMBOL(dma_fence_init); |