From: Thierry Reding <thierry.reding@gmail.com>
To: Sui Jingfeng <suijingfeng@loongson.cn>
Cc: Mikko Perttunen <mperttunen@nvidia.com>,
David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>,
Jonathan Hunter <jonathanh@nvidia.com>,
dri-devel@lists.freedesktop.org, linux-tegra@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] drm/tegra: Return an error code if fails
Date: Tue, 10 Oct 2023 15:22:56 +0200 [thread overview]
Message-ID: <ZSVQMPuRnXzC0lgf@orome.fritz.box> (raw)
In-Reply-To: <20230626143331.640454-1-suijingfeng@loongson.cn>
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On Mon, Jun 26, 2023 at 10:33:30PM +0800, Sui Jingfeng wrote:
> Return -ENOMEM if tegra_bo_mmap() fails.
>
> Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn>
> ---
> drivers/gpu/drm/tegra/gem.c | 2 ++
> 1 file changed, 2 insertions(+)
Sorry, this fell through the cracks. I think it'd be better if
tegra_bo_mmap() were to be improved to always return either an ERR_PTR()
encoded error code or a valid pointer. Throwing NULL into the mix isn't
useful because it typically means something like -ENOMEM anyway. Error
codes are more explicit, so since we're already using them for some
cases, might as well return them for all.
Actually, looks like tegra_bo_mmap() never actually returns an ERR_PTR()
encoded error code. It's either obj->vaddr, the return value of vmap()
(which is either NULL or the address of the mapping), or the address
obtained from dma_buf_vmap_unlocked() (i.e. map.vaddr) or NULL on
failure. So I think it would equally make sense to keep your patch and
to remove the IS_ERR() check below it.
I would slightly prefer the first option, but either is fine.
Thierry
> diff --git a/drivers/gpu/drm/tegra/gem.c b/drivers/gpu/drm/tegra/gem.c
> index dea38892d6e6..0ce22935fbd3 100644
> --- a/drivers/gpu/drm/tegra/gem.c
> +++ b/drivers/gpu/drm/tegra/gem.c
> @@ -710,6 +710,8 @@ static int tegra_gem_prime_vmap(struct dma_buf *buf, struct iosys_map *map)
> void *vaddr;
>
> vaddr = tegra_bo_mmap(&bo->base);
> + if (!vaddr)
> + return -ENOMEM;
> if (IS_ERR(vaddr))
> return PTR_ERR(vaddr);
>
> --
> 2.25.1
>
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next prev parent reply other threads:[~2023-10-10 13:23 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-26 14:33 [PATCH 1/2] drm/tegra: Return an error code if fails Sui Jingfeng
2023-06-26 14:33 ` [PATCH 2/2] drm/tegra: Remove surplus else after return Sui Jingfeng
2023-10-10 15:28 ` Thierry Reding
2023-07-27 10:02 ` [1/2] drm/tegra: Return an error code if fails suijingfeng
2023-10-10 13:22 ` Thierry Reding [this message]
2023-10-10 15:31 ` [PATCH 1/2] " Thierry Reding
2023-10-11 3:06 ` Sui Jingfeng
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