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Date:   Fri, 1 Feb 2019 15:51:43 +0100
From:   Pierre Moreau <pierre.morrow@free.fr>
To:     Ben Skeggs <bskeggs@redhat.com>
Cc:     YueHaibing <yuehaibing@huawei.com>,
        David Airlie <airlied@linux.ie>, nouveau@lists.freedesktop.org,
        kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org
Subject: Re: [Nouveau] [PATCH -next] drm/nouveau: fix copy-paste error in
 nouveau_fence_wait_uevent_handler
Message-ID: <20190201145143.vwiljlpfa5waqyr7@pmoreau.org>
Mail-Followup-To: Ben Skeggs <bskeggs@redhat.com>,
        YueHaibing <yuehaibing@huawei.com>, David Airlie <airlied@linux.ie>,
        nouveau@lists.freedesktop.org, kernel-janitors@vger.kernel.org,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org
References: <1542284042-153903-1-git-send-email-yuehaibing@huawei.com>
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Friendly ping, Ben.
I see that in `nouveau_fence_done()` there is a check on `chan` not being NULL
prior to passing it to `nouveau_fence_update()`. Would something similar be
needed here?

Pierre

On 2018-11-15 — 12:14, YueHaibing wrote:
> Fixes gcc '-Wunused-but-set-variable' warning:
> 
> drivers/gpu/drm/nouveau/nouveau_fence.c: In function 'nouveau_fence_wait_uevent_handler':
> drivers/gpu/drm/nouveau/nouveau_fence.c:156:27: warning:
>  variable 'chan' set but not used [-Wunused-but-set-variable]
> 
> nouveau_fence_update should use rcu protected 'chan'
> rather than 'fence->channel'
> 
> Fixes: 0ec5f02f0e2c ("drm/nouveau: prevent stale fence->channel pointers, and protect with rcu")
> Signed-off-by: YueHaibing <yuehaibing@huawei.com>
> ---
>  drivers/gpu/drm/nouveau/nouveau_fence.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c b/drivers/gpu/drm/nouveau/nouveau_fence.c
> index d4964f3..91286d0 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_fence.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_fence.c
> @@ -157,7 +157,7 @@
>  
>  		fence = list_entry(fctx->pending.next, typeof(*fence), head);
>  		chan = rcu_dereference_protected(fence->channel, lockdep_is_held(&fctx->lock));
> -		if (nouveau_fence_update(fence->channel, fctx))
> +		if (nouveau_fence_update(chan, fctx))
>  			ret = NVIF_NOTIFY_DROP;
>  	}
>  	spin_unlock_irqrestore(&fctx->lock, flags);
> 
> 
> 
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