| Message ID | 20230626143331.640454-1-suijingfeng@loongson.cn (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] drm/tegra: Return an error code if fails | expand |
Hi, Gentle ping for this series. On 2023/6/26 22:33, 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(+) > > 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); >
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 >
On Tue, Oct 10, 2023 at 03:22:56PM +0200, Thierry Reding wrote: > 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. How about the attached patch? Thierry From b34a09efcf7b1d2c25d3baf8c6d91c5ca09b4e0f Mon Sep 17 00:00:00 2001 From: Thierry Reding <treding@nvidia.com> Date: Tue, 10 Oct 2023 17:26:14 +0200 Subject: [PATCH] drm/tegra: gem: Do not return NULL in tegra_bo_mmap() It's confusing for a function to return NULL and ERR_PTR()-encoded error codes on failure. Make sure we only ever return the latter since that's what callers already expect. Signed-off-by: Thierry Reding <treding@nvidia.com> --- drivers/gpu/drm/tegra/gem.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/tegra/gem.c b/drivers/gpu/drm/tegra/gem.c index 11296de59c5a..679460e05c05 100644 --- a/drivers/gpu/drm/tegra/gem.c +++ b/drivers/gpu/drm/tegra/gem.c @@ -178,6 +178,7 @@ static void *tegra_bo_mmap(struct host1x_bo *bo) { struct tegra_bo *obj = host1x_to_tegra_bo(bo); struct iosys_map map; + void *vaddr; int ret; if (obj->vaddr) @@ -185,10 +186,18 @@ static void *tegra_bo_mmap(struct host1x_bo *bo) if (obj->gem.import_attach) { ret = dma_buf_vmap_unlocked(obj->gem.import_attach->dmabuf, &map); - return ret ? NULL : map.vaddr; + if (ret < 0) + return ERR_PTR(ret); + + return map.vaddr; } - return vmap(obj->pages, obj->num_pages, VM_MAP, pgprot_writecombine(PAGE_KERNEL)); + vaddr = vmap(obj->pages, obj->num_pages, VM_MAP, + pgprot_writecombine(PAGE_KERNEL)); + if (!vaddr) + return -ENOMEM; + + return vaddr; } static void tegra_bo_munmap(struct host1x_bo *bo, void *addr)
Hi, On 2023/10/10 23:31, Thierry Reding wrote: > On Tue, Oct 10, 2023 at 03:22:56PM +0200, Thierry Reding wrote: >> 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. > How about the attached patch? I also prefer the prefer the first option. The attached patch is more better, because it solve the problem at lower level. Reviewed-by: Sui Jingfeng <suijingfeng@loongson.cn> > 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);
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(+)