linux-kernel - [PATCH v3] x86/apic: Improve data types to fix Coccinelle warnings

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Message-ID: <20240308230228.3161-2-thorsten.blum@toblux.com>
Date: Sat,  9 Mar 2024 00:02:29 +0100
From: Thorsten Blum <thorsten.blum@...lux.com>
To: thorsten.blum@...lux.com
Cc: David.Laight@...LAB.COM,
	bp@...en8.de,
	dave.hansen@...el.com,
	dave.hansen@...ux.intel.com,
	hpa@...or.com,
	linux-kernel@...r.kernel.org,
	mingo@...hat.com,
	peterz@...radead.org,
	tglx@...utronix.de,
	wei.liu@...nel.org,
	x86@...nel.org
Subject: [PATCH v3] x86/apic: Improve data types to fix Coccinelle warnings

Given that acpi_pm_read_early() returns a u32 (masked to 24 bits), several
variables that store its return value are improved by adjusting their data
types from unsigned long to u32. Specifically, change deltapm's type from
long to u32 because its value fits into 32 bits and it cannot be negative.

These data type improvements resolve the following two Coccinelle/
coccicheck warnings reported by do_div.cocci:

arch/x86/kernel/apic/apic.c:734:1-7: WARNING: do_div() does a 64-by-32
division, please consider using div64_long instead.

arch/x86/kernel/apic/apic.c:742:2-8: WARNING: do_div() does a 64-by-32
division, please consider using div64_long instead.

Signed-off-by: Thorsten Blum <thorsten.blum@...lux.com>
---
Changes in v2:
- Revert changing do_div() to div64_ul() after feedback from David Laight
- Use u32 instead of unsigned long to fix Coccinelle warnings
- Update patch title and description

Changes in v3:
- Adjust patch summary and description after feedback from Dave Hansen
---
 arch/x86/kernel/apic/apic.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 4667bc4b00ab..184e1843620d 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -664,7 +664,7 @@ void lapic_update_tsc_freq(void)
 static __initdata int lapic_cal_loops = -1;
 static __initdata long lapic_cal_t1, lapic_cal_t2;
 static __initdata unsigned long long lapic_cal_tsc1, lapic_cal_tsc2;
-static __initdata unsigned long lapic_cal_pm1, lapic_cal_pm2;
+static __initdata u32 lapic_cal_pm1, lapic_cal_pm2;
 static __initdata unsigned long lapic_cal_j1, lapic_cal_j2;
 
 /*
@@ -674,7 +674,7 @@ static void __init lapic_cal_handler(struct clock_event_device *dev)
 {
 	unsigned long long tsc = 0;
 	long tapic = apic_read(APIC_TMCCT);
-	unsigned long pm = acpi_pm_read_early();
+	u32 pm = acpi_pm_read_early();
 
 	if (boot_cpu_has(X86_FEATURE_TSC))
 		tsc = rdtsc();
@@ -699,7 +699,7 @@ static void __init lapic_cal_handler(struct clock_event_device *dev)
 }
 
 static int __init
-calibrate_by_pmtimer(long deltapm, long *delta, long *deltatsc)
+calibrate_by_pmtimer(u32 deltapm, long *delta, long *deltatsc)
 {
 	const long pm_100ms = PMTMR_TICKS_PER_SEC / 10;
 	const long pm_thresh = pm_100ms / 100;
@@ -710,7 +710,7 @@ calibrate_by_pmtimer(long deltapm, long *delta, long *deltatsc)
 	return -1;
 #endif
 
-	apic_printk(APIC_VERBOSE, "... PM-Timer delta = %ld\n", deltapm);
+	apic_printk(APIC_VERBOSE, "... PM-Timer delta = %u\n", deltapm);
 
 	/* Check, if the PM timer is available */
 	if (!deltapm)
-- 
2.44.0