linux-kernel - [PATCH AUTOSEL 6.12 275/486] drm/xe/oa: Ensure that polled read returns latest data

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Message-Id: <20250505223922.2682012-275-sashal@kernel.org>
Date: Mon,  5 May 2025 18:35:51 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@...el.com>,
	Ashutosh Dixit <ashutosh.dixit@...el.com>,
	Sasha Levin <sashal@...nel.org>,
	lucas.demarchi@...el.com,
	thomas.hellstrom@...ux.intel.com,
	rodrigo.vivi@...el.com,
	airlied@...il.com,
	simona@...ll.ch,
	intel-xe@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 6.12 275/486] drm/xe/oa: Ensure that polled read returns latest data

From: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@...el.com>

[ 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@...el.com>
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@...el.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250212010255.1423343-1-umesh.nerlige.ramappa@intel.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/xe/xe_oa.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/xe/xe_oa.c b/drivers/gpu/drm/xe/xe_oa.c
index 448766033690c..d306ed0a04434 100644
--- a/drivers/gpu/drm/xe/xe_oa.c
+++ b/drivers/gpu/drm/xe/xe_oa.c
@@ -535,6 +535,7 @@ 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);
-- 
2.39.5