linux-kernel - Re: linux-next: build failure after merge of the drm-misc tree

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Date:   Tue, 2 Apr 2019 21:56:08 +0800
From:   Qiang Yu <yuq825@...il.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Stephen Rothwell <sfr@...b.auug.org.au>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Intel Graphics <intel-gfx@...ts.freedesktop.org>,
        DRI <dri-devel@...ts.freedesktop.org>,
        Linux Next Mailing List <linux-next@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Eric Anholt <eric@...olt.net>
Subject: Re: linux-next: build failure after merge of the drm-misc tree

On Tue, Apr 2, 2019 at 7:26 PM Matthew Wilcox <willy@...radead.org> wrote:
>
> On Tue, Apr 02, 2019 at 01:55:03PM +0800, Qiang Yu wrote:
> > Thanks, patch is:
> > Reviewed-by: Qiang Yu <yuq825@...il.com>
>
> This looks like a fairly naive conversion from the old IDR API to the
> XArray API.  You should be able to remove mgr->lock entirely, relying on
> the xa_lock for synchronising free and get.

I'm afraid the a little complex free path may involve some might sleep
functions so use a mutex lock instead of spinlock.

> If you think it's worth it,
> you could even use kfree_rcu() to free the ctx and kref_get_unless_zero()
> and then your get path would be lock-free.

I can take a look this way, thanks.