[Linaro-mm-sig] Re: [PATCH v10 07/15] dma-buf/sw_sync: Add fence deadline support

On 08/03/2023 15:52, Rob Clark wrote:

From: Rob Clark robdclark@chromium.org

This consists of simply storing the most recent deadline, and adding an ioctl to retrieve the deadline. This can be used in conjunction with the SET_DEADLINE ioctl on a fence fd for testing. Ie. create various sw_sync fences, merge them into a fence-array, set deadline on the fence-array and confirm that it is propagated properly to each fence.

v2: Switch UABI to express deadline as u64 v3: More verbose UAPI docs, show how to convert from timespec v4: Better comments, track the soonest deadline, as a normal fence implementation would, return an error if no deadline set.

Signed-off-by: Rob Clark robdclark@chromium.org Reviewed-by: Christian König christian.koenig@amd.com Acked-by: Pekka Paalanen pekka.paalanen@collabora.com

---

drivers/dma-buf/sw_sync.c | 81 ++++++++++++++++++++++++++++++++++++ drivers/dma-buf/sync_debug.h | 2 + 2 files changed, 83 insertions(+)

diff --git a/drivers/dma-buf/sw_sync.c b/drivers/dma-buf/sw_sync.c index 348b3a9170fa..f53071bca3af 100644 --- a/drivers/dma-buf/sw_sync.c +++ b/drivers/dma-buf/sw_sync.c @@ -52,12 +52,33 @@ struct sw_sync_create_fence_data { __s32 fence; /* fd of new fence */ }; +/**

• • struct sw_sync_get_deadline - get the deadline hint of a sw_sync fence
• • @deadline_ns: absolute time of the deadline
• • @pad: must be zero
• • @fence_fd: the sw_sync fence fd (in)
• • Return the earliest deadline set on the fence. The timebase for the
• • deadline is CLOCK_MONOTONIC (same as vblank). If there is no deadline

Mentioning vblank reads odd since this is drivers/dma-buf/. Dunno.

• • set on the fence, this ioctl will return -ENOENT.
• */

+struct sw_sync_get_deadline {

• __u64 deadline_ns;
• __u32 pad;
• __s32 fence_fd;

+};

• #define SW_SYNC_IOC_MAGIC 'W'

#define SW_SYNC_IOC_CREATE_FENCE _IOWR(SW_SYNC_IOC_MAGIC, 0,\ struct sw_sync_create_fence_data) #define SW_SYNC_IOC_INC _IOW(SW_SYNC_IOC_MAGIC, 1, __u32) +#define SW_SYNC_GET_DEADLINE _IOWR(SW_SYNC_IOC_MAGIC, 2, \

• struct sw_sync_get_deadline)
  

+#define SW_SYNC_HAS_DEADLINE_BIT DMA_FENCE_FLAG_USER_BITS static const struct dma_fence_ops timeline_fence_ops; @@ -171,6 +192,22 @@ static void timeline_fence_timeline_value_str(struct dma_fence *fence, snprintf(str, size, "%d", parent->value); } +static void timeline_fence_set_deadline(struct dma_fence *fence, ktime_t deadline) +{

• struct sync_pt *pt = dma_fence_to_sync_pt(fence);
• unsigned long flags;
• spin_lock_irqsave(fence->lock, flags);
• if (test_bit(SW_SYNC_HAS_DEADLINE_BIT, &fence->flags)) {

• if (ktime_before(deadline, pt->deadline))
  

• 	pt->deadline = deadline;
  

• } else {

• pt->deadline = deadline;
  

• set_bit(SW_SYNC_HAS_DEADLINE_BIT, &fence->flags);
  

FWIW could use __set_bit to avoid needless atomic under spinlock.

• }
• spin_unlock_irqrestore(fence->lock, flags);

+}

• static const struct dma_fence_ops timeline_fence_ops = { .get_driver_name = timeline_fence_get_driver_name, .get_timeline_name = timeline_fence_get_timeline_name,

@@ -179,6 +216,7 @@ static const struct dma_fence_ops timeline_fence_ops = { .release = timeline_fence_release, .fence_value_str = timeline_fence_value_str, .timeline_value_str = timeline_fence_timeline_value_str,

• .set_deadline = timeline_fence_set_deadline, };

/** @@ -387,6 +425,46 @@ static long sw_sync_ioctl_inc(struct sync_timeline *obj, unsigned long arg) return 0; } +static int sw_sync_ioctl_get_deadline(struct sync_timeline *obj, unsigned long arg) +{

• struct sw_sync_get_deadline data;
• struct dma_fence *fence;
• struct sync_pt *pt;
• int ret = 0;
• if (copy_from_user(&data, (void __user *)arg, sizeof(data)))

• return -EFAULT;
  

• if (data.deadline_ns || data.pad)

• return -EINVAL;
  

• fence = sync_file_get_fence(data.fence_fd);
• if (!fence)

• return -EINVAL;
  

• pt = dma_fence_to_sync_pt(fence);
• if (!pt)

• return -EINVAL;
  

• spin_lock(fence->lock);

This may need to be _irq.

• if (test_bit(SW_SYNC_HAS_DEADLINE_BIT, &fence->flags)) {

• data.deadline_ns = ktime_to_ns(pt->deadline);
  

• } else {

• ret = -ENOENT;
  

• }
• spin_unlock(fence->lock);
• dma_fence_put(fence);
• if (ret)

• return ret;
  

• if (copy_to_user((void __user *)arg, &data, sizeof(data)))

• return -EFAULT;
  

• return 0;

+}

• static long sw_sync_ioctl(struct file *file, unsigned int cmd, unsigned long arg) {

@@ -399,6 +477,9 @@ static long sw_sync_ioctl(struct file *file, unsigned int cmd, case SW_SYNC_IOC_INC: return sw_sync_ioctl_inc(obj, arg);

• case SW_SYNC_GET_DEADLINE:

• return sw_sync_ioctl_get_deadline(obj, arg);
  

• default: return -ENOTTY; }

diff --git a/drivers/dma-buf/sync_debug.h b/drivers/dma-buf/sync_debug.h index 6176e52ba2d7..a1bdd62efccd 100644 --- a/drivers/dma-buf/sync_debug.h +++ b/drivers/dma-buf/sync_debug.h @@ -55,11 +55,13 @@ static inline struct sync_timeline *dma_fence_parent(struct dma_fence *fence)

• @base: base fence object
• @link: link on the sync timeline's list
• @node: node in the sync timeline's tree

• • @deadline: the earliest fence deadline hint
  */ struct sync_pt { struct dma_fence base; struct list_head link; struct rb_node node;
• ktime_t deadline; };

extern const struct file_operations sw_sync_debugfs_fops;

Regards,

Tvrtko