linux-kernel - [PATCH] gpu: drm: msm: use div64_u64() instead of do

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Message-Id: <1644395837-3845-1-git-send-email-wangqing@vivo.com>
Date:   Wed,  9 Feb 2022 00:37:17 -0800
From:   Qing Wang <wangqing@...o.com>
To:     Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, linux-arm-msm@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Cc:     Wang Qing <wangqing@...o.com>
Subject: [PATCH] gpu: drm: msm: use div64_u64() instead of do_div()

From: Wang Qing <wangqing@...o.com>

do_div() does a 64-by-32 division.
When the divisor is u64, do_div() truncates it to 32 bits, this means it
can test non-zero and be truncated to zero for division.

fix do_div.cocci warning:
do_div() does a 64-by-32 division, please consider using div64_u64 instead.

Signed-off-by: Wang Qing <wangqing@...o.com>
---
 drivers/gpu/drm/msm/msm_gpu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
index 2c1049c..aa4617b
--- a/drivers/gpu/drm/msm/msm_gpu.c
+++ b/drivers/gpu/drm/msm/msm_gpu.c
@@ -648,7 +648,7 @@ static void retire_submit(struct msm_gpu *gpu, struct msm_ringbuffer *ring,
 	/* Calculate the clock frequency from the number of CP cycles */
 	if (elapsed) {
 		clock = (stats->cpcycles_end - stats->cpcycles_start) * 1000;
-		do_div(clock, elapsed);
+		div64_u64(clock, elapsed);
 	}
 
 	trace_msm_gpu_submit_retired(submit, elapsed, clock,
-- 
2.7.4