From: Thierry Reding <thierry.reding@gmail.com>
To: David Herrmann <dh.herrmann@gmail.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>,
"dri-devel@lists.freedesktop.org"
<dri-devel@lists.freedesktop.org>
Subject: Re: [PATCH 1/2] drm: make idr_mutex a spinlock
Date: Fri, 29 Aug 2014 15:17:30 +0200 [thread overview]
Message-ID: <20140829131729.GV17519@ulmo> (raw)
In-Reply-To: <CANq1E4T5xULD6grCje1bvu=Gf=MuggxOQEz_T+HhqgRNhCNGMg@mail.gmail.com>
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On Fri, Aug 29, 2014 at 03:11:19PM +0200, David Herrmann wrote:
> Hi
>
> On Fri, Aug 29, 2014 at 3:10 PM, Thierry Reding
> <thierry.reding@gmail.com> wrote:
> > On Fri, Aug 29, 2014 at 02:01:00PM +0200, David Herrmann wrote:
> >> There is no reason to use a heavy mutex for idr protection. Use a spinlock
> >> and make idr-allocation use idr_preload().
> >>
> >> This patch also makes mode-object lookup irq-save, in case you ever wanna
> >> lookup modeset objects from interrupts. This is just a side-effect of
> >> avoiding a mutex.
> >
> > I don't think that's entirely accurate. idr_preload(GFP_KERNEL) might
> > sleep since GFP_KERNEL & __GFP_WAIT != 0.
>
> idr_preload() is only used in registration, not in lookups. Not sure
> what you refer to?
Yes, you're right. I wasn't paying close enough attention and somehow
applied "makes irq-safe" to the "idr_preload()" change without relating
it to "lookup".
Thierry
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prev parent reply other threads:[~2014-08-29 13:17 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-29 12:01 [PATCH 1/2] drm: make idr_mutex a spinlock David Herrmann
2014-08-29 12:01 ` [PATCH 2/2] drm: don't recycle used modeset IDs David Herrmann
2014-08-29 12:51 ` Daniel Vetter
2014-08-29 12:57 ` David Herrmann
2014-08-29 13:10 ` David Herrmann
2014-08-29 15:22 ` Rob Clark
2014-08-29 13:32 ` Daniel Vetter
2014-08-29 12:53 ` [PATCH 1/2] drm: make idr_mutex a spinlock Daniel Vetter
2014-08-29 13:03 ` David Herrmann
2014-08-29 13:34 ` Daniel Vetter
2014-08-29 13:10 ` Thierry Reding
2014-08-29 13:11 ` David Herrmann
2014-08-29 13:17 ` Thierry Reding [this message]
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