linux-kernel - [PATCH] perf/x86/amd/power: Use div64_u64 onstead of do

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Date: Sun, 28 Apr 2024 17:40:25 +0100
From: Jules Irenge <jbi.octave@...il.com>
To: mark.rutland@....com
Cc: alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
	irogers@...gle.com, adrian.hunter@...el.com, bp@...en8.de,
	dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] perf/x86/amd/power: Use div64_u64 onstead of do_div()

do_div() truncates a u64 divisor to 32 bit.
This can lead to non-zero being truncated to zero for division.

Fix coccinelle warning
WARNING: do_div() does a 64-by-32 division, please consider using div64_u64 instead

Signed-off-by: Jules Irenge <jbi.octave@...il.com>
---
 arch/x86/events/amd/power.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/events/amd/power.c b/arch/x86/events/amd/power.c
index 37d5b380516e..ff003c1a645b 100644
--- a/arch/x86/events/amd/power.c
+++ b/arch/x86/events/amd/power.c
@@ -64,7 +64,7 @@ static void event_update(struct perf_event *event)
 	delta *= cpu_pwr_sample_ratio * 1000;
 	tdelta = new_ptsc - prev_ptsc;
 
-	do_div(delta, tdelta);
+	div64_u64(delta, tdelta);
 	local64_add(delta, &event->count);
 }
 
-- 
2.43.2