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From: Pingfan Liu <kernelfans@gmail.com>
To: Heiko Carstens <hca@linux.ibm.com>
Cc: linux-s390@vger.kernel.org, Vasily Gorbik <gor@linux.ibm.com>,
	Alexander Gordeev <agordeev@linux.ibm.com>,
	Christian Borntraeger <borntraeger@linux.ibm.com>,
	Sven Schnelle <svens@linux.ibm.com>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/9] s390/irq: utilize RCU instead of irq_lock_sparse() in show_msi_interrupt()
Date: Fri, 22 Apr 2022 17:56:37 +0800	[thread overview]
Message-ID: <YmJ71apr/9MPtT7g@piliu.users.ipa.redhat.com> (raw)
In-Reply-To: <YmFDQ0wH+Y15bKX0@osiris>

On Thu, Apr 21, 2022 at 01:42:59PM +0200, Heiko Carstens wrote:
> On Thu, Apr 21, 2022 at 11:36:17AM +0800, Pingfan Liu wrote:
> > Oops. You are right. What about using rcu_read_lock() directly?
> > 
> > 
> > diff --git a/arch/s390/kernel/irq.c b/arch/s390/kernel/irq.c
> > index 3033f616e256..45393919fe61 100644
> > --- a/arch/s390/kernel/irq.c
> > +++ b/arch/s390/kernel/irq.c
> > @@ -205,7 +205,7 @@ static void show_msi_interrupt(struct seq_file *p, int irq)
> >  	unsigned long flags;
> >  	int cpu;
> >  
> > -	irq_lock_sparse();
> > +	rcu_read_lock();
> >  	desc = irq_to_desc(irq);
> >  	if (!desc)
> >  		goto out;
> > @@ -224,7 +224,7 @@ static void show_msi_interrupt(struct seq_file *p, int irq)
> >  	seq_putc(p, '\n');
> >  	raw_spin_unlock_irqrestore(&desc->lock, flags);
> >  out:
> > -	irq_unlock_sparse();
> > +	rcu_read_unlock();
> 
> That looks like it should work. Please resend and also add a reference
> to commit 74bdf7815dfb ("genirq: Speedup show_interrupts()") which
> explains why this works.

Thanks for your review. I will follow up with V2.

Regards,

	Pingfan

  reply	other threads:[~2022-04-22  9:56 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-20 14:05 [PATCH 0/9] trival fix or improvement about irq_desc access Pingfan Liu
2022-04-20 14:05 ` [PATCH 1/9] irq/irqdesc: put the lock at the exact place in irq_sysfs_init() Pingfan Liu
2022-04-20 14:05 ` [PATCH 2/9] irq/irqdesc: change the name of delete_irq_desc() to irq_delete_desc() Pingfan Liu
2022-04-20 14:05 ` [PATCH 3/9] irq/manage: remove some unreferenced code Pingfan Liu
2022-04-20 20:56   ` Miguel Ojeda
2022-04-20 14:05 ` [PATCH 4/9] s390/irq: utilize RCU instead of irq_lock_sparse() in show_msi_interrupt() Pingfan Liu
2022-04-20 18:16   ` Heiko Carstens
2022-04-21  3:36     ` Pingfan Liu
2022-04-21 11:42       ` Heiko Carstens
2022-04-22  9:56         ` Pingfan Liu [this message]
2022-04-22 10:02   ` [PATCHv2] " Pingfan Liu
2022-04-25 11:39     ` Heiko Carstens
2022-04-20 14:05 ` [PATCH 5/9] x86/irq: place for_each_active_irq() in rcu read section Pingfan Liu
2022-04-20 14:05 ` [PATCH 6/9] pm/irq: make for_each_irq_desc() safe of irq_desc release Pingfan Liu
2022-04-20 16:23   ` Rafael J. Wysocki
2022-04-21  3:31     ` Pingfan Liu
2022-04-21 10:57       ` Rafael J. Wysocki
2022-04-22 10:43         ` Pingfan Liu
2022-04-27  6:03   ` [PATCHv2] genirq/PM: Make " Pingfan Liu
2022-04-20 14:05 ` [PATCH 7/9] irq: remove needless lock in takedown_cpu() Pingfan Liu
2022-04-21 16:11   ` Thomas Gleixner
2022-04-25  2:57     ` Pingfan Liu
2022-04-25  9:43       ` Thomas Gleixner
2022-04-27  6:01         ` Pingfan Liu
2022-04-20 14:05 ` [PATCH 8/9] irq: make irq_lock_sparse() independent of CONFIG_SPARSE_IRQ Pingfan Liu
2022-04-20 14:05 ` [PATCH 9/9] irq/irqdesc: rename sparse_irq_lock to bitmap_lock Pingfan Liu

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