LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Alexei Lozovsky <me@ilammy.net>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Alexey Dobriyan <adobriyan@gmail.com>,
	Christoph Lameter <cl@linux.com>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org
Subject: [PATCH 2/7] powerpc/irq: arch_irq_stat_cpu() returns unsigned int
Date: Sat, 11 Sep 2021 12:48:03 +0900	[thread overview]
Message-ID: <20210911034808.24252-3-me@ilammy.net> (raw)
In-Reply-To: <20210911034808.24252-1-me@ilammy.net>

The interrupt counters this function sums up are all unsigned int
(see irq_cpustat_t). If the sum overflows, so be it: you should
monitor the counter and take note when it wraps around.

Summing up unsigned int values into u64 does not "handle" overflows,
but if any of the individual counters overflows then the computed
sum is inaccurate.

Signed-off-by: Alexei Lozovsky <me@ilammy.net>
---
 arch/powerpc/include/asm/hardirq.h | 2 +-
 arch/powerpc/kernel/irq.c          | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/hardirq.h b/arch/powerpc/include/asm/hardirq.h
index f133b5930ae1..5248adcb50b4 100644
--- a/arch/powerpc/include/asm/hardirq.h
+++ b/arch/powerpc/include/asm/hardirq.h
@@ -32,7 +32,7 @@ static inline void ack_bad_irq(unsigned int irq)
 	printk(KERN_CRIT "unexpected IRQ trap at vector %02x\n", irq);
 }
 
-extern u64 arch_irq_stat_cpu(unsigned int cpu);
+extern unsigned int arch_irq_stat_cpu(unsigned int cpu);
 #define arch_irq_stat_cpu	arch_irq_stat_cpu
 
 #endif /* _ASM_POWERPC_HARDIRQ_H */
diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 551b653228c4..a100c967892e 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -645,9 +645,9 @@ int arch_show_interrupts(struct seq_file *p, int prec)
 /*
  * /proc/stat helpers
  */
-u64 arch_irq_stat_cpu(unsigned int cpu)
+unsigned int arch_irq_stat_cpu(unsigned int cpu)
 {
-	u64 sum = per_cpu(irq_stat, cpu).timer_irqs_event;
+	unsigned int sum = per_cpu(irq_stat, cpu).timer_irqs_event;
 
 	sum += per_cpu(irq_stat, cpu).broadcast_irqs_event;
 	sum += per_cpu(irq_stat, cpu).pmu_irqs;
-- 
2.25.1


  parent reply	other threads:[~2021-09-11  3:48 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-10  8:53 /proc/stat interrupt counter wrap-around Alexei Lozovsky
2021-09-11  3:48 ` [PATCH 0/7] proc/stat: Maintain monotonicity of "intr" and "softirq" Alexei Lozovsky
2021-09-11  3:48   ` [PATCH 1/7] genirq: Use unsigned int for irqs_sum Alexei Lozovsky
2021-09-11  3:48   ` Alexei Lozovsky [this message]
2021-09-11  3:48   ` [PATCH 3/7] x86/irq: arch_irq_stat_cpu() returns unsigned int Alexei Lozovsky
2021-09-11  3:48   ` [PATCH 4/7] x86/irq: arch_irq_stat() " Alexei Lozovsky
2021-09-11  3:48   ` [PATCH 5/7] proc/stat: Use unsigned int for "intr" sum Alexei Lozovsky
2021-09-11  3:48   ` [PATCH 6/7] proc/stat: Use unsigned int for "softirq" sum Alexei Lozovsky
2021-09-11  3:48   ` [PATCH 7/7] docs: proc.rst: stat: Note the interrupt counter wrap-around Alexei Lozovsky
2021-09-11  3:59     ` Randy Dunlap
2021-09-12  9:30   ` [PATCH 0/7] proc/stat: Maintain monotonicity of "intr" and "softirq" Alexey Dobriyan
2021-09-12 12:37     ` Alexei Lozovsky
2021-09-14 14:11       ` Thomas Gleixner
2021-09-15  4:24         ` Alexei Lozovsky
2021-09-15 17:58   ` [PATCH v2 00/12] " Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 01/12] genirq: Use READ_ONCE for IRQ counter reads Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 02/12] genirq: Use unsigned long for IRQ counters Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 03/12] powerpc/irq: Use READ_ONCE for IRQ counter reads Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 04/12] powerpc/irq: Use unsigned long for IRQ counters Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 05/12] powerpc/irq: Use unsigned long for IRQ counter sum Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 06/12] x86/irq: Use READ_ONCE for IRQ counter reads Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 07/12] x86/irq: Use unsigned long for IRQ counters Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 08/12] x86/irq: Use unsigned long for IRQ counters more Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 09/12] x86/irq: Use unsigned long for IRQ counter sum Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 10/12] proc/stat: Use unsigned long for "intr" sum Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 11/12] proc/stat: Use unsigned long for "softirq" sum Alexei Lozovsky
2021-09-15 17:58     ` [PATCH v2 12/12] docs: proc.rst: stat: Note the interrupt counter wrap-around Alexei Lozovsky

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210911034808.24252-3-me@ilammy.net \
    --to=me@ilammy.net \
    --cc=adobriyan@gmail.com \
    --cc=cl@linux.com \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=tglx@linutronix.de \
    --subject='Re: [PATCH 2/7] powerpc/irq: arch_irq_stat_cpu() returns unsigned int' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).