drm/xe/oa: Ensure that polled read returns latest data

[ Upstream commit 98c9d27ab30aa9c6451d3a34e6e297171f273e51 ]

In polled mode, user calls poll() for read data to be available before
performing a read(). In the duration between these 2 calls, there may be
new data available in the OA buffer. To ensure user reads all available
data, check for latest data in the OA buffer in polled read.

Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250212010255.1423343-1-umesh.nerlige.ramappa@intel.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/xe/xe_oa.c b/drivers/gpu/drm/xe/xe_oa.c
index eb6cd91e1e2265d07926387b5fc04880998a8e3d..abf37d9ab221293c0a401eedf2506d8717129f54 100644 (file)
--- a/drivers/gpu/drm/xe/xe_oa.c
+++ b/drivers/gpu/drm/xe/xe_oa.c
@@ -548,6 +548,7 @@ static ssize_t xe_oa_read(struct file *file, char __user *buf,
                        mutex_unlock(&stream->stream_lock);
                } while (!offset && !ret);
        } else {
+               xe_oa_buffer_check_unlocked(stream);
                mutex_lock(&stream->stream_lock);
                ret = __xe_oa_read(stream, buf, count, &offset);
                mutex_unlock(&stream->stream_lock);