linux-kernel - Re: [PATCH 1/1] drm/amdkfd: Create file descriptor after client is added to smi

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Message-ID: <YkSVDnolf1jltrSR@google.com>
Date:   Wed, 30 Mar 2022 18:36:14 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Felix Kuehling <felix.kuehling@....com>
Cc:     linux-kernel@...r.kernel.org,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        "Pan, Xinhui" <Xinhui.Pan@....com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH 1/1] drm/amdkfd: Create file descriptor after client is
 added to smi_clients list

On Wed, 30 Mar 2022, Felix Kuehling wrote:

> 
> Am 2022-03-30 um 03:51 schrieb Lee Jones:
> > This ensures userspace cannot prematurely clean-up the client before
> > it is fully initialised which has been proven to cause issues in the
> > past.
> > 
> > Cc: Felix Kuehling <Felix.Kuehling@....com>
> > Cc: Alex Deucher <alexander.deucher@....com>
> > Cc: "Christian König" <christian.koenig@....com>
> > Cc: "Pan, Xinhui" <Xinhui.Pan@....com>
> > Cc: David Airlie <airlied@...ux.ie>
> > Cc: Daniel Vetter <daniel@...ll.ch>
> > Cc: amd-gfx@...ts.freedesktop.org
> > Cc: dri-devel@...ts.freedesktop.org
> > Signed-off-by: Lee Jones <lee.jones@...aro.org>
> > ---
> >   drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c | 18 +++++++++---------
> >   1 file changed, 9 insertions(+), 9 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c b/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
> > index e4beebb1c80a2..c5d5398d45cbf 100644
> > --- a/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
> > +++ b/drivers/gpu/drm/amd/amdkfd/kfd_smi_events.c
> > @@ -247,15 +247,6 @@ int kfd_smi_event_open(struct kfd_dev *dev, uint32_t *fd)
> >   		return ret;
> >   	}
> > -	ret = anon_inode_getfd(kfd_smi_name, &kfd_smi_ev_fops, (void *)client,
> > -			       O_RDWR);
> > -	if (ret < 0) {
> > -		kfifo_free(&client->fifo);
> > -		kfree(client);
> > -		return ret;
> > -	}
> > -	*fd = ret;
> > -
> >   	init_waitqueue_head(&client->wait_queue);
> >   	spin_lock_init(&client->lock);
> >   	client->events = 0;
> > @@ -265,5 +256,14 @@ int kfd_smi_event_open(struct kfd_dev *dev, uint32_t *fd)
> >   	list_add_rcu(&client->list, &dev->smi_clients);
> >   	spin_unlock(&dev->smi_lock);
> > +	ret = anon_inode_getfd(kfd_smi_name, &kfd_smi_ev_fops, (void *)client,
> > +			       O_RDWR);
> > +	if (ret < 0) {
> 
> Thank you for the patch. This looks like the correct solution. But you also
> need to remove the client from the dev->smi_clients list here before
> kfree(client). With that fixed, the patch is

Yes, that makes perfect sense.

> Reviewed-by: Felix Kuehling <Felix.Kuehling@....com>

Thanks Felix.  I will provide a follow-up tomorrow.

-- 
Lee Jones [李琼斯]
Principal Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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