linux-kernel - Re: [PATCH v2 2/3] drm: Add a drm_gem_objects

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Message-ID: <8736n120jw.fsf@anholt.net>
Date:   Mon, 01 Apr 2019 08:43:47 -0700
From:   Eric Anholt <eric@...olt.net>
To:     Chris Wilson <chris@...is-wilson.co.uk>,
        Daniel Vetter <daniel@...ll.ch>, Rob Herring <robh@...nel.org>
Cc:     Neil Armstrong <narmstrong@...libre.com>,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        Robin Murphy <robin.murphy@....com>,
        Will Deacon <will.deacon@....com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        David Airlie <airlied@...ux.ie>,
        "list\@263.net\:IOMMU DRIVERS \<iommu\@lists.linux-foundation.org\>\, 
        Joerg Roedel \<joro\@8bytes.org\>\, " 
        <iommu@...ts.linux-foundation.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Sean Paul <sean@...rly.run>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>
Subject: Re: [PATCH v2 2/3] drm: Add a drm_gem_objects_lookup helper

Chris Wilson <chris@...is-wilson.co.uk> writes:

> Quoting Daniel Vetter (2019-04-01 14:06:48)
>> On Mon, Apr 1, 2019 at 9:47 AM Rob Herring <robh@...nel.org> wrote:
>> > +{
>> > +       int i, ret = 0;
>> > +       struct drm_gem_object *obj;
>> > +
>> > +       spin_lock(&filp->table_lock);
>> > +
>> > +       for (i = 0; i < count; i++) {
>> > +               /* Check if we currently have a reference on the object */
>> > +               obj = idr_find(&filp->object_idr, handle[i]);
>> > +               if (!obj) {
>> > +                       ret = -ENOENT;
>
> Unwind previous drm_gem_object_get(), the caller has no idea how many
> were processed before the error.

I had the same thought, but the pattern we have is that you're loading
into a refcounted struct that will free the BOs when you're done,
anyway.

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