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From: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
To: Sebastian Andrzej Siewior
	<bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
Cc: Andrew Morton
	<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
Subject: Re: [PATCH 2/3] iommu/iova: don't disable preempt around this_cpu_ptr()
Date: Wed, 28 Jun 2017 12:26:25 +0200	[thread overview]
Message-ID: <20170628102625.GJ14532@8bytes.org> (raw)
In-Reply-To: <20170628093154.ncrcvwretfcoizx3-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>

On Wed, Jun 28, 2017 at 11:31:55AM +0200, Sebastian Andrzej Siewior wrote:
> It really does. The spin_lock() does disable preemption but this is not
> the problem. The thing is that the preempt_disable() is superfluous and
> it hurts Preempt-RT (and this is how I noticed it). Also the
> get_cpu_ptr() is not requited and was only added to keep lockdep quiet
> (according to the history).
> Everything else here can stay as-is, I am just asking for the removal of
> the redundant preempt_disable() where it is not required.

Okay, makes sense, I applied both patches.


Thanks,

	Joerg

WARNING: multiple messages have this Message-ID (diff)
From: Joerg Roedel <joro@8bytes.org>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: tglx@linutronix.de, linux-kernel@vger.kernel.org,
	iommu@lists.linux-foundation.org,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 2/3] iommu/iova: don't disable preempt around this_cpu_ptr()
Date: Wed, 28 Jun 2017 12:26:25 +0200	[thread overview]
Message-ID: <20170628102625.GJ14532@8bytes.org> (raw)
In-Reply-To: <20170628093154.ncrcvwretfcoizx3@linutronix.de>

On Wed, Jun 28, 2017 at 11:31:55AM +0200, Sebastian Andrzej Siewior wrote:
> It really does. The spin_lock() does disable preemption but this is not
> the problem. The thing is that the preempt_disable() is superfluous and
> it hurts Preempt-RT (and this is how I noticed it). Also the
> get_cpu_ptr() is not requited and was only added to keep lockdep quiet
> (according to the history).
> Everything else here can stay as-is, I am just asking for the removal of
> the redundant preempt_disable() where it is not required.

Okay, makes sense, I applied both patches.


Thanks,

	Joerg

  parent reply	other threads:[~2017-06-28 10:26 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-27 16:16 [PATCH 1/3] rbtree: include rcu.h because we use it Sebastian Andrzej Siewior
2017-06-27 16:16 ` [PATCH 2/3] iommu/iova: don't disable preempt around this_cpu_ptr() Sebastian Andrzej Siewior
     [not found]   ` <20170627161648.30302-2-bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
2017-06-28  9:22     ` Joerg Roedel
2017-06-28  9:22       ` Joerg Roedel
     [not found]       ` <20170628092205.GB30388-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2017-06-28  9:31         ` Sebastian Andrzej Siewior
2017-06-28  9:31           ` Sebastian Andrzej Siewior
     [not found]           ` <20170628093154.ncrcvwretfcoizx3-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
2017-06-28 10:26             ` Joerg Roedel [this message]
2017-06-28 10:26               ` Joerg Roedel
     [not found] ` <20170627161648.30302-1-bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
2017-06-27 16:16   ` [PATCH 3/3] iommu/vt-d: don't disable preemption while accessing deferred_flush() Sebastian Andrzej Siewior
2017-06-27 16:16     ` Sebastian Andrzej Siewior

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