From: Rob Clark robdclark@chromium.org
Add a way to initialize a fence without touching the refcount. This is useful, for example, if the fence is embedded in a drm_sched_job. In this case the refcount will be initialized before the job is queued. But the seqno of the hw_fence is not known until job_run().
Signed-off-by: Rob Clark robdclark@chromium.org --- drivers/dma-buf/dma-fence.c | 43 ++++++++++++++++++++++++++++--------- include/linux/dma-fence.h | 2 ++ 2 files changed, 35 insertions(+), 10 deletions(-)
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c index 0de0482cd36e..3c55f946084c 100644 --- a/drivers/dma-buf/dma-fence.c +++ b/drivers/dma-buf/dma-fence.c @@ -929,28 +929,27 @@ void dma_fence_describe(struct dma_fence *fence, struct seq_file *seq) EXPORT_SYMBOL(dma_fence_describe);
/** - * dma_fence_init - Initialize a custom fence. + * dma_fence_init_noref - Initialize a custom fence without initializing refcount. * @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(). + * Like &dma_fence_init but does not initialize the refcount. Suitable + * for cases where the fence is embedded in another struct which has it's + * refcount initialized before the fence is initialized. Such as embedding + * in a &drm_sched_job, where the job is created before knowing the seqno + * of the hw_fence. */ void -dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops, - spinlock_t *lock, u64 context, u64 seqno) +dma_fence_init_noref(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); + BUG_ON(!kref_read(&fence->refcount));
- kref_init(&fence->refcount); fence->ops = ops; INIT_LIST_HEAD(&fence->cb_list); fence->lock = lock; @@ -961,4 +960,28 @@ dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops,
trace_dma_fence_init(fence); } +EXPORT_SYMBOL(dma_fence_init_noref); + +/** + * 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) +{ + kref_init(&fence->refcount); + dma_fence_init_noref(fence, ops, lock, context, seqno); +} EXPORT_SYMBOL(dma_fence_init); diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h index 775cdc0b4f24..89d90a2b5f09 100644 --- a/include/linux/dma-fence.h +++ b/include/linux/dma-fence.h @@ -259,6 +259,8 @@ struct dma_fence_ops { char *str, int size); };
+void dma_fence_init_noref(struct dma_fence *fence, const struct dma_fence_ops *ops, + spinlock_t *lock, u64 context, u64 seqno); void dma_fence_init(struct dma_fence *fence, const struct dma_fence_ops *ops, spinlock_t *lock, u64 context, u64 seqno);