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From: Amos Kong <akong@redhat.com>
To: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>,
	virtualization@lists.linux-foundation.org, kvm@vger.kernel.org,
	amit.shah@redhat.com, jasowang@redhat.com,
	linux-kernel@vger.kernel.org, m@bues.ch,
	herbert@gondor.apana.org.au, mpm@selenic.com
Subject: Re: [PATCH 2/2] virtio-rng: fix stuck in catting hwrng attributes
Date: Tue, 16 Sep 2014 08:50:03 +0800	[thread overview]
Message-ID: <20140916005003.GC5671@zen> (raw)
In-Reply-To: <20140915164846.GA29862@potion.brq.redhat.com>

CC linux-kernel

Original thread: http://comments.gmane.org/gmane.linux.kernel.virtualization/22775

On Mon, Sep 15, 2014 at 06:48:46PM +0200, Radim Krčmář wrote:
> 2014-09-14 10:25+0800, Amos Kong:
> > On Sun, Sep 14, 2014 at 09:12:08AM +0800, Amos Kong wrote:
> > 
> > ...
> > > > > > diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
> > > > > > index c591d7e..b5d1b6f 100644
> > > > > > --- a/drivers/char/hw_random/core.c
> > > > > > +++ b/drivers/char/hw_random/core.c
> > > > > > @@ -195,8 +195,7 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf,
> > > > > >  
> > > > > >  		mutex_unlock(&rng_mutex);
> > > > > >  
> > > > > > -		if (need_resched())
> > > > > > -			schedule_timeout_interruptible(1);
> > > > > > +		schedule_timeout_interruptible(10);
> 
> If cond_resched() does not work, it is a bug elsewehere.

Thanks for your reply, Jason also told me the TIF_NEED_RESCHED should
be set in this case, then need_resched() returns true.

I will investigate the issue and reply you later.
 
> > Problem only occurred in non-smp guest, we can improve it to:
> > 
> >                         if(!is_smp())
> >                                 schedule_timeout_interruptible(10);
> > 
> > is_smp() is only available for arm arch, we need a general one.
> 
> (It is num_online_cpus() > 1.)

-- 
			Amos.

WARNING: multiple messages have this Message-ID (diff)
From: Amos Kong <akong@redhat.com>
To: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: herbert@gondor.apana.org.au, kvm@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org, m@bues.ch,
	mpm@selenic.com, amit.shah@redhat.com
Subject: Re: [PATCH 2/2] virtio-rng: fix stuck in catting hwrng attributes
Date: Tue, 16 Sep 2014 08:50:03 +0800	[thread overview]
Message-ID: <20140916005003.GC5671@zen> (raw)
In-Reply-To: <20140915164846.GA29862@potion.brq.redhat.com>

CC linux-kernel

Original thread: http://comments.gmane.org/gmane.linux.kernel.virtualization/22775

On Mon, Sep 15, 2014 at 06:48:46PM +0200, Radim Krčmář wrote:
> 2014-09-14 10:25+0800, Amos Kong:
> > On Sun, Sep 14, 2014 at 09:12:08AM +0800, Amos Kong wrote:
> > 
> > ...
> > > > > > diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
> > > > > > index c591d7e..b5d1b6f 100644
> > > > > > --- a/drivers/char/hw_random/core.c
> > > > > > +++ b/drivers/char/hw_random/core.c
> > > > > > @@ -195,8 +195,7 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf,
> > > > > >  
> > > > > >  		mutex_unlock(&rng_mutex);
> > > > > >  
> > > > > > -		if (need_resched())
> > > > > > -			schedule_timeout_interruptible(1);
> > > > > > +		schedule_timeout_interruptible(10);
> 
> If cond_resched() does not work, it is a bug elsewehere.

Thanks for your reply, Jason also told me the TIF_NEED_RESCHED should
be set in this case, then need_resched() returns true.

I will investigate the issue and reply you later.
 
> > Problem only occurred in non-smp guest, we can improve it to:
> > 
> >                         if(!is_smp())
> >                                 schedule_timeout_interruptible(10);
> > 
> > is_smp() is only available for arm arch, we need a general one.
> 
> (It is num_online_cpus() > 1.)

-- 
			Amos.
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Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

  reply	other threads:[~2014-09-16  0:51 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-10  9:07 [PATCH 0/2] fix stuck in catting hwrng attributes Amos Kong
2014-09-10  9:07 ` [PATCH 1/2] virtio-rng cleanup: move some code out of mutex protection Amos Kong
2014-09-11  6:07   ` Amit Shah
2014-09-10  9:07 ` [PATCH 2/2] virtio-rng: fix stuck in catting hwrng attributes Amos Kong
2014-09-11  6:08   ` Amit Shah
2014-09-14  1:16     ` Amos Kong
2014-09-11 11:38   ` Rusty Russell
2014-09-13 17:12     ` Amos Kong
2014-09-14  1:12       ` Amos Kong
2014-09-14  2:25         ` Amos Kong
2014-09-15 16:48           ` Radim Krčmář
2014-09-16  0:50             ` Amos Kong [this message]
2014-09-16  0:50               ` Amos Kong
2014-09-16 15:35         ` Rusty Russell

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