[Intel-xe] [PATCH] drm/xe: Use milliseconds instead of jiffies in uapi for user fence

[Zbigniew Kempczyński]

Using jiffies as a timeout from userspace is weird even it theoretically
exists possiblity of acquiring jiffies via getconf. Unfortunately this
method is unreliable and returned value may vary from configured in the
kernel config.

Due to kernel constraints regarding milliseconds type (unsigned int)
conversion to jiffies and uapi timeout defined as u64 return an error
if timeout exceeds unsigned int size.

Signed-off-by: Zbigniew Kempczyński <zbigniew.kempczynski at intel.com>

---
v2: build break typo fix
---
 drivers/gpu/drm/xe/xe_wait_user_fence.c | 13 +++++++++++--
 include/uapi/drm/xe_drm.h               |  2 +-
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_wait_user_fence.c b/drivers/gpu/drm/xe/xe_wait_user_fence.c
index 15c2e5aa08d2..b587dce2976e 100644
--- a/drivers/gpu/drm/xe/xe_wait_user_fence.c
+++ b/drivers/gpu/drm/xe/xe_wait_user_fence.c
@@ -79,6 +79,13 @@ static int check_hw_engines(struct xe_device *xe,
 	return 0;
 }
 
+static unsigned long msecs_to_jiffies_timeout(const unsigned int m)
+{
+	unsigned long j = msecs_to_jiffies(m);
+
+	return min_t(unsigned long, MAX_JIFFY_OFFSET, j + 1);
+}
+
 #define VALID_FLAGS	(DRM_XE_UFENCE_WAIT_SOFT_OP | \
 			 DRM_XE_UFENCE_WAIT_ABSTIME | \
 			 DRM_XE_UFENCE_WAIT_VM_ERROR)
@@ -98,7 +105,7 @@ int xe_wait_user_fence_ioctl(struct drm_device *dev, void *data,
 	int err;
 	bool no_engines = args->flags & DRM_XE_UFENCE_WAIT_SOFT_OP ||
 		args->flags & DRM_XE_UFENCE_WAIT_VM_ERROR;
-	unsigned long timeout = args->timeout;
+	unsigned long timeout;
 
 	if (XE_IOCTL_ERR(xe, args->extensions))
 		return -EINVAL;
@@ -148,9 +155,11 @@ int xe_wait_user_fence_ioctl(struct drm_device *dev, void *data,
 		addr = vm->async_ops.error_capture.addr;
 	}
 
-	if (XE_IOCTL_ERR(xe, timeout > MAX_SCHEDULE_TIMEOUT))
+	if (XE_IOCTL_ERR(xe, args->timeout > UINT_MAX))
 		return -EINVAL;
 
+	timeout = msecs_to_jiffies_timeout(args->timeout);
+
 	/*
 	 * FIXME: Very simple implementation at the moment, single wait queue
 	 * for everything. Could be optimized to have a wait queue for every
diff --git a/include/uapi/drm/xe_drm.h b/include/uapi/drm/xe_drm.h
index b0b80aae3ee8..3e6f679ab534 100644
--- a/include/uapi/drm/xe_drm.h
+++ b/include/uapi/drm/xe_drm.h
@@ -726,7 +726,7 @@ struct drm_xe_wait_user_fence {
 #define DRM_XE_UFENCE_WAIT_U32		0xffffffffu
 #define DRM_XE_UFENCE_WAIT_U64		0xffffffffffffffffu
 	__u64 mask;
-	/** @timeout: how long to wait before bailing, value in jiffies */
+	/** @timeout: how long to wait before bailing, value in milliseconds */
 	__s64 timeout;
 	/**
 	 * @num_engines: number of engine instances to wait on, must be zero
-- 
2.40.0