| Message ID | 20211014102551.54983-1-guangming.cao@mediatek.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3] dma-buf: remove restriction of IOCTL:DMA_BUF_SET_NAME | expand |
From: Guangming Cao <Guangming.Cao@mediatek.com> On Wed, 2021-10-13 at 14:20 +0200, Christian König wrote: > Am 13.10.21 um 01:56 schrieb Sumit Semwal: > > Hello Guangming, Christian, > > > > > > > > On Tue, 12 Oct 2021, 14:09 , <guangming.cao@mediatek.com> wrote: > > > From: Guangming Cao <Guangming.Cao@mediatek.com> > > > > > > > Am 09.10.21 um 07:55 schrieb guangming.cao@mediatek.com: > > > > From: Guangming Cao <Guangming.Cao@mediatek.com> > > > > > > > > > > If dma-buf don't want userspace users to touch the dmabuf > > > buffer, > > > > > it seems we should add this restriction into > > > dma_buf_ops.mmap, > > > > > not in this IOCTL:DMA_BUF_SET_NAME. > > > > > > > > > > With this restriction, we can only know the kernel users of > > > the dmabuf > > > > > by attachments. > > > > > However, for many userspace users, such as userpsace users of > > > dma_heap, > > > > > they also need to mark the usage of dma-buf, and they don't > > > care about > > > > > who attached to this dmabuf, and seems it's no meaning to be > > > waiting for > > > > > IOCTL:DMA_BUF_SET_NAME rather than mmap. > > > > > > > > Sounds valid to me, but I have no idea why this restriction was > > > added in > > > > the first place. > > > > > > > > Can you double check the git history and maybe identify when > > > that was > > > > added? Mentioning this change in the commit message then might > > > make > > > > things a bit easier to understand. > > > > > > > > Thanks, > > > > Christian. > > > It was add in this patch: > > > https://patchwork.freedesktop.org/patch/310349/. > > > However, there is no illustration about it. > > > I guess it wants users to set_name when no attachments on the > > > dmabuf, > > > for case with attachments, we can find owner by device in > > > attachments. > > > But just I said in commit message, this is might not a good idea. > > > > > > Do you have any idea? > > > > > > > For the original series, the idea was that allowing name change > > mid-use could confuse the users about the dma-buf. However, the > > rest of the series also makes sure each dma-buf have a unique > > inode, and any accounting should probably use that, without relying > > on the name as much. > > So I don't have an objection to this change. > > I suggest to add that explanation and the original commit id into the > commit message. > > With that changed the patch has my rb as well. > > Regards, > Christian. > updated, thanks! Guangming. > > Best, > > Sumit. > > > > > > > > > > > > > > Signed-off-by: Guangming Cao <Guangming.Cao@mediatek.com> > > > > > --- > > > > > drivers/dma-buf/dma-buf.c | 14 ++------------ > > > > > 1 file changed, 2 insertions(+), 12 deletions(-) > > > > > > > > > > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma- > > > buf.c > > > > > index 511fe0d217a0..db2f4efdec32 100644 > > > > > --- a/drivers/dma-buf/dma-buf.c > > > > > +++ b/drivers/dma-buf/dma-buf.c > > > > > @@ -325,10 +325,8 @@ static __poll_t dma_buf_poll(struct file > > > *file, poll_table *poll) > > > > > > > > > > /** > > > > > * dma_buf_set_name - Set a name to a specific dma_buf to > > > track the usage. > > > > > - * The name of the dma-buf buffer can only be set when the > > > dma-buf is not > > > > > - * attached to any devices. It could theoritically support > > > changing the > > > > > - * name of the dma-buf if the same piece of memory is used > > > for multiple > > > > > - * purpose between different devices. > > > > > + * It could theoretically support changing the name of the > > > dma-buf if the same > > > > > + * piece of memory is used for multiple purpose between > > > different devices. > > > > > * > > > > > * @dmabuf: [in] dmabuf buffer that will be renamed. > > > > > * @buf: [in] A piece of userspace memory that > > > contains the name of > > > > > @@ -346,19 +344,11 @@ static long dma_buf_set_name(struct > > > dma_buf *dmabuf, const char __user *buf) > > > > > if (IS_ERR(name)) > > > > > return PTR_ERR(name); > > > > > > > > > > - dma_resv_lock(dmabuf->resv, NULL); > > > > > - if (!list_empty(&dmabuf->attachments)) { > > > > > - ret = -EBUSY; > > > > > - kfree(name); > > > > > - goto out_unlock; > > > > > - } > > > > > spin_lock(&dmabuf->name_lock); > > > > > kfree(dmabuf->name); > > > > > dmabuf->name = name; > > > > > spin_unlock(&dmabuf->name_lock); > > > > > > > > > > -out_unlock: > > > > > - dma_resv_unlock(dmabuf->resv); > > > > > return ret; > > > > > } > > > > > > > > >
From: Guangming Cao <Guangming.Cao@mediatek.com> On Thu, 2021-10-14 at 18:25 +0800, guangming.cao@mediatek.com wrote: > From: Guangming Cao <Guangming.Cao@mediatek.com> > > In this patch(https://patchwork.freedesktop.org/patch/310349), > it add a new IOCTL to support dma-buf user to set debug name. > > But it also added a limitation of this IOCTL, it needs the > attachments of dmabuf should be empty, otherwise it will fail. > > For the original series, the idea was that allowing name change > mid-use could confuse the users about the dma-buf. > However, the rest of the series also makes sure each dma-buf have a > unique > inode(https://patchwork.freedesktop.org/patch/310387/), and any > accounting > should probably use that, without relying on the name as much. > > So, removing this restriction will let dma-buf userspace users to use > it > more comfortably and without any side effect. > Hi christian, sumit, Just a gentle ping for this patch, please kindly let me know your comments about this patch. Thanks! Guangming > Signed-off-by: Guangming Cao <Guangming.Cao@mediatek.com> > --- > drivers/dma-buf/dma-buf.c | 17 +++-------------- > 1 file changed, 3 insertions(+), 14 deletions(-) > > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c > index 511fe0d217a0..5fbb3a2068a3 100644 > --- a/drivers/dma-buf/dma-buf.c > +++ b/drivers/dma-buf/dma-buf.c > @@ -325,10 +325,8 @@ static __poll_t dma_buf_poll(struct file *file, > poll_table *poll) > > /** > * dma_buf_set_name - Set a name to a specific dma_buf to track the > usage. > - * The name of the dma-buf buffer can only be set when the dma-buf > is not > - * attached to any devices. It could theoritically support changing > the > - * name of the dma-buf if the same piece of memory is used for > multiple > - * purpose between different devices. > + * It could support changing the name of the dma-buf if the same > + * piece of memory is used for multiple purpose between different > devices. > * > * @dmabuf: [in] dmabuf buffer that will be renamed. > * @buf: [in] A piece of userspace memory that contains the > name of > @@ -341,25 +339,16 @@ static __poll_t dma_buf_poll(struct file *file, > poll_table *poll) > static long dma_buf_set_name(struct dma_buf *dmabuf, const char > __user *buf) > { > char *name = strndup_user(buf, DMA_BUF_NAME_LEN); > - long ret = 0; > > if (IS_ERR(name)) > return PTR_ERR(name); > > - dma_resv_lock(dmabuf->resv, NULL); > - if (!list_empty(&dmabuf->attachments)) { > - ret = -EBUSY; > - kfree(name); > - goto out_unlock; > - } > spin_lock(&dmabuf->name_lock); > kfree(dmabuf->name); > dmabuf->name = name; > spin_unlock(&dmabuf->name_lock); > > -out_unlock: > - dma_resv_unlock(dmabuf->resv); > - return ret; > + return 0; > } > > static long dma_buf_ioctl(struct file *file,
Am 14.10.21 um 12:25 schrieb guangming.cao@mediatek.com: > From: Guangming Cao <Guangming.Cao@mediatek.com> > > In this patch(https://patchwork.freedesktop.org/patch/310349), > it add a new IOCTL to support dma-buf user to set debug name. > > But it also added a limitation of this IOCTL, it needs the > attachments of dmabuf should be empty, otherwise it will fail. > > For the original series, the idea was that allowing name change > mid-use could confuse the users about the dma-buf. > However, the rest of the series also makes sure each dma-buf have a unique > inode(https://patchwork.freedesktop.org/patch/310387/), and any accounting > should probably use that, without relying on the name as much. > > So, removing this restriction will let dma-buf userspace users to use it > more comfortably and without any side effect. > > Signed-off-by: Guangming Cao <Guangming.Cao@mediatek.com> We could now cleanup the return value from dma_buf_set_name() into a void since that function can't fail any more as far as I can see. But that isn't mandatory I think, patch is Reviewed-by: Christian König <christian.koenig@amd.com> Regards, Christian. > --- > drivers/dma-buf/dma-buf.c | 17 +++-------------- > 1 file changed, 3 insertions(+), 14 deletions(-) > > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c > index 511fe0d217a0..5fbb3a2068a3 100644 > --- a/drivers/dma-buf/dma-buf.c > +++ b/drivers/dma-buf/dma-buf.c > @@ -325,10 +325,8 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll) > > /** > * dma_buf_set_name - Set a name to a specific dma_buf to track the usage. > - * The name of the dma-buf buffer can only be set when the dma-buf is not > - * attached to any devices. It could theoritically support changing the > - * name of the dma-buf if the same piece of memory is used for multiple > - * purpose between different devices. > + * It could support changing the name of the dma-buf if the same > + * piece of memory is used for multiple purpose between different devices. > * > * @dmabuf: [in] dmabuf buffer that will be renamed. > * @buf: [in] A piece of userspace memory that contains the name of > @@ -341,25 +339,16 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll) > static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf) > { > char *name = strndup_user(buf, DMA_BUF_NAME_LEN); > - long ret = 0; > > if (IS_ERR(name)) > return PTR_ERR(name); > > - dma_resv_lock(dmabuf->resv, NULL); > - if (!list_empty(&dmabuf->attachments)) { > - ret = -EBUSY; > - kfree(name); > - goto out_unlock; > - } > spin_lock(&dmabuf->name_lock); > kfree(dmabuf->name); > dmabuf->name = name; > spin_unlock(&dmabuf->name_lock); > > -out_unlock: > - dma_resv_unlock(dmabuf->resv); > - return ret; > + return 0; > } > > static long dma_buf_ioctl(struct file *file,
From: Guangming Cao <Guangming.Cao@mediatek.com> On Tue, 2021-10-26 at 13:18 +0200, Christian König wrote: > Am 14.10.21 um 12:25 schrieb guangming.cao@mediatek.com: > > From: Guangming Cao <Guangming.Cao@mediatek.com> > > > > In this patch(https://patchwork.freedesktop.org/patch/310349), > > it add a new IOCTL to support dma-buf user to set debug name. > > > > But it also added a limitation of this IOCTL, it needs the > > attachments of dmabuf should be empty, otherwise it will fail. > > > > For the original series, the idea was that allowing name change > > mid-use could confuse the users about the dma-buf. > > However, the rest of the series also makes sure each dma-buf have a > > unique > > inode(https://patchwork.freedesktop.org/patch/310387/), and any > > accounting > > should probably use that, without relying on the name as much. > > > > So, removing this restriction will let dma-buf userspace users to > > use it > > more comfortably and without any side effect. > > > > Signed-off-by: Guangming Cao <Guangming.Cao@mediatek.com> > > We could now cleanup the return value from dma_buf_set_name() into a > void since that function can't fail any more as far as I can see. > > But that isn't mandatory I think, patch is Reviewed-by: Christian > König > <christian.koenig@amd.com> > So, here is no need to check return value of 'strndup_user', just return without error code if the almost impossible error occurs? Guangming. > Regards, > Christian. > > > --- > > drivers/dma-buf/dma-buf.c | 17 +++-------------- > > 1 file changed, 3 insertions(+), 14 deletions(-) > > > > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c > > index 511fe0d217a0..5fbb3a2068a3 100644 > > --- a/drivers/dma-buf/dma-buf.c > > +++ b/drivers/dma-buf/dma-buf.c > > @@ -325,10 +325,8 @@ static __poll_t dma_buf_poll(struct file > > *file, poll_table *poll) > > > > /** > > * dma_buf_set_name - Set a name to a specific dma_buf to track > > the usage. > > - * The name of the dma-buf buffer can only be set when the dma-buf > > is not > > - * attached to any devices. It could theoritically support > > changing the > > - * name of the dma-buf if the same piece of memory is used for > > multiple > > - * purpose between different devices. > > + * It could support changing the name of the dma-buf if the same > > + * piece of memory is used for multiple purpose between different > > devices. > > * > > * @dmabuf: [in] dmabuf buffer that will be renamed. > > * @buf: [in] A piece of userspace memory that contains > > the name of > > @@ -341,25 +339,16 @@ static __poll_t dma_buf_poll(struct file > > *file, poll_table *poll) > > static long dma_buf_set_name(struct dma_buf *dmabuf, const char > > __user *buf) > > { > > char *name = strndup_user(buf, DMA_BUF_NAME_LEN); > > - long ret = 0; > > > > if (IS_ERR(name)) > > return PTR_ERR(name); > > > > - dma_resv_lock(dmabuf->resv, NULL); > > - if (!list_empty(&dmabuf->attachments)) { > > - ret = -EBUSY; > > - kfree(name); > > - goto out_unlock; > > - } > > spin_lock(&dmabuf->name_lock); > > kfree(dmabuf->name); > > dmabuf->name = name; > > spin_unlock(&dmabuf->name_lock); > > > > -out_unlock: > > - dma_resv_unlock(dmabuf->resv); > > - return ret; > > + return 0; > > } > > > > static long dma_buf_ioctl(struct file *file, > >
Am 26.10.21 um 13:52 schrieb guangming.cao@mediatek.com: > From: Guangming Cao <Guangming.Cao@mediatek.com> > > On Tue, 2021-10-26 at 13:18 +0200, Christian König wrote: >> Am 14.10.21 um 12:25 schrieb guangming.cao@mediatek.com: >>> From: Guangming Cao <Guangming.Cao@mediatek.com> >>> >>> In this patch(https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatchwork.freedesktop.org%2Fpatch%2F310349&data=04%7C01%7Cchristian.koenig%40amd.com%7C6652f423b96547b8321308d998772121%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637708459727236977%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=4EFg60sCxQzNuMKB0VjhbpvoeGlcAbofErMtcjPtIfw%3D&reserved=0), >>> it add a new IOCTL to support dma-buf user to set debug name. >>> >>> But it also added a limitation of this IOCTL, it needs the >>> attachments of dmabuf should be empty, otherwise it will fail. >>> >>> For the original series, the idea was that allowing name change >>> mid-use could confuse the users about the dma-buf. >>> However, the rest of the series also makes sure each dma-buf have a >>> unique >>> inode(https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatchwork.freedesktop.org%2Fpatch%2F310387%2F&data=04%7C01%7Cchristian.koenig%40amd.com%7C6652f423b96547b8321308d998772121%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637708459727236977%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=c%2Bbso%2BSxiPjwlv%2B9tAzA4x0gf5UktREhSiAsODFkihk%3D&reserved=0), and any >>> accounting >>> should probably use that, without relying on the name as much. >>> >>> So, removing this restriction will let dma-buf userspace users to >>> use it >>> more comfortably and without any side effect. >>> >>> Signed-off-by: Guangming Cao <Guangming.Cao@mediatek.com> >> We could now cleanup the return value from dma_buf_set_name() into a >> void since that function can't fail any more as far as I can see. >> >> But that isn't mandatory I think, patch is Reviewed-by: Christian >> König >> <christian.koenig@amd.com> >> > So, here is no need to check return value of 'strndup_user', > just return without error code if the almost impossible error occurs? Good point, totally missed that one. In that case I'm going to push the patch to drm-misc-next as is. Regards, Christian. > > Guangming. > >> Regards, >> Christian. >> >>> --- >>> drivers/dma-buf/dma-buf.c | 17 +++-------------- >>> 1 file changed, 3 insertions(+), 14 deletions(-) >>> >>> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c >>> index 511fe0d217a0..5fbb3a2068a3 100644 >>> --- a/drivers/dma-buf/dma-buf.c >>> +++ b/drivers/dma-buf/dma-buf.c >>> @@ -325,10 +325,8 @@ static __poll_t dma_buf_poll(struct file >>> *file, poll_table *poll) >>> >>> /** >>> * dma_buf_set_name - Set a name to a specific dma_buf to track >>> the usage. >>> - * The name of the dma-buf buffer can only be set when the dma-buf >>> is not >>> - * attached to any devices. It could theoritically support >>> changing the >>> - * name of the dma-buf if the same piece of memory is used for >>> multiple >>> - * purpose between different devices. >>> + * It could support changing the name of the dma-buf if the same >>> + * piece of memory is used for multiple purpose between different >>> devices. >>> * >>> * @dmabuf: [in] dmabuf buffer that will be renamed. >>> * @buf: [in] A piece of userspace memory that contains >>> the name of >>> @@ -341,25 +339,16 @@ static __poll_t dma_buf_poll(struct file >>> *file, poll_table *poll) >>> static long dma_buf_set_name(struct dma_buf *dmabuf, const char >>> __user *buf) >>> { >>> char *name = strndup_user(buf, DMA_BUF_NAME_LEN); >>> - long ret = 0; >>> >>> if (IS_ERR(name)) >>> return PTR_ERR(name); >>> >>> - dma_resv_lock(dmabuf->resv, NULL); >>> - if (!list_empty(&dmabuf->attachments)) { >>> - ret = -EBUSY; >>> - kfree(name); >>> - goto out_unlock; >>> - } >>> spin_lock(&dmabuf->name_lock); >>> kfree(dmabuf->name); >>> dmabuf->name = name; >>> spin_unlock(&dmabuf->name_lock); >>> >>> -out_unlock: >>> - dma_resv_unlock(dmabuf->resv); >>> - return ret; >>> + return 0; >>> } >>> >>> static long dma_buf_ioctl(struct file *file, >>
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 511fe0d217a0..5fbb3a2068a3 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -325,10 +325,8 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll) /** * dma_buf_set_name - Set a name to a specific dma_buf to track the usage. - * The name of the dma-buf buffer can only be set when the dma-buf is not - * attached to any devices. It could theoritically support changing the - * name of the dma-buf if the same piece of memory is used for multiple - * purpose between different devices. + * It could support changing the name of the dma-buf if the same + * piece of memory is used for multiple purpose between different devices. * * @dmabuf: [in] dmabuf buffer that will be renamed. * @buf: [in] A piece of userspace memory that contains the name of @@ -341,25 +339,16 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll) static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf) { char *name = strndup_user(buf, DMA_BUF_NAME_LEN); - long ret = 0; if (IS_ERR(name)) return PTR_ERR(name); - dma_resv_lock(dmabuf->resv, NULL); - if (!list_empty(&dmabuf->attachments)) { - ret = -EBUSY; - kfree(name); - goto out_unlock; - } spin_lock(&dmabuf->name_lock); kfree(dmabuf->name); dmabuf->name = name; spin_unlock(&dmabuf->name_lock); -out_unlock: - dma_resv_unlock(dmabuf->resv); - return ret; + return 0; } static long dma_buf_ioctl(struct file *file,