2017-04-06 14:30:40

by zhangshuxiaomi

Subject: [PATCH] staging: android: ashmem: lseek failed due to no FMODE_LSEEK.

From: zhangshuxiao <[email protected]>

vfs_llseek will check whether the file mode has
FMODE_LSEEK, no return failure. But ashmem can be
lseek, so add FMODE_LSEEK to ashmem file.

Signed-off-by: Shuxiao Zhang <[email protected]>
Tested-by: Greg Hackmann <[email protected]>
---
drivers/staging/android/ashmem.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c
index 3f11332..e4530ac 100644
--- a/drivers/staging/android/ashmem.c
+++ b/drivers/staging/android/ashmem.c
@@ -392,6 +392,7 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
ret = PTR_ERR(vmfile);
goto out;
}
+ vmfile->f_mode |= FMODE_LSEEK;
asma->file = vmfile;
}
get_file(asma->file);
--
1.9.1

2017-04-06 15:30:52

by Greg Hackmann

Subject: Re: [PATCH] staging: android: ashmem: lseek failed due to no FMODE_LSEEK.

On 04/06/2017 07:30 AM, [email protected] wrote:
> From: zhangshuxiao <[email protected]>
>
> vfs_llseek will check whether the file mode has
> FMODE_LSEEK, no return failure. But ashmem can be
> lseek, so add FMODE_LSEEK to ashmem file.
>
> Signed-off-by: Shuxiao Zhang <[email protected]>
> Tested-by: Greg Hackmann <[email protected]>
> ---
> drivers/staging/android/ashmem.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c
> index 3f11332..e4530ac 100644
> --- a/drivers/staging/android/ashmem.c
> +++ b/drivers/staging/android/ashmem.c
> @@ -392,6 +392,7 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
> ret = PTR_ERR(vmfile);
> goto out;
> }
> + vmfile->f_mode |= FMODE_LSEEK;
> asma->file = vmfile;
> }
> get_file(asma->file);
>

This commit message is missing some important context.

ashmem_llseek() passes the llseek() call through to the backing shmem
file. 91360b02ab48 ("ashmem: use vfs_llseek()") changed this from
directly calling the file's llseek() op into a VFS layer call. This
also adds a check for the FMODE_LSEEK bit, so without that bit
ashmem_llseek() now always fails with -ESPIPE.

I've tested that this patch fixes the regression on both hikey running
AOSP and User Mode Linux running Debian.

2017-04-06 17:08:32

by Greg Kroah-Hartman

Subject: Re: [PATCH] staging: android: ashmem: lseek failed due to no FMODE_LSEEK.

On Thu, Apr 06, 2017 at 08:30:40AM -0700, Greg Hackmann wrote:
> On 04/06/2017 07:30 AM, [email protected] wrote:
> > From: zhangshuxiao <[email protected]>
> >
> > vfs_llseek will check whether the file mode has
> > FMODE_LSEEK, no return failure. But ashmem can be
> > lseek, so add FMODE_LSEEK to ashmem file.
> >
> > Signed-off-by: Shuxiao Zhang <[email protected]>
> > Tested-by: Greg Hackmann <[email protected]>
> > ---
> > drivers/staging/android/ashmem.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c
> > index 3f11332..e4530ac 100644
> > --- a/drivers/staging/android/ashmem.c
> > +++ b/drivers/staging/android/ashmem.c
> > @@ -392,6 +392,7 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
> > ret = PTR_ERR(vmfile);
> > goto out;
> > }
> > + vmfile->f_mode |= FMODE_LSEEK;
> > asma->file = vmfile;
> > }
> > get_file(asma->file);
> >
>
> This commit message is missing some important context.
>
> ashmem_llseek() passes the llseek() call through to the backing shmem file.
> 91360b02ab48 ("ashmem: use vfs_llseek()") changed this from directly calling
> the file's llseek() op into a VFS layer call. This also adds a check for
> the FMODE_LSEEK bit, so without that bit ashmem_llseek() now always fails
> with -ESPIPE.
>
> I've tested that this patch fixes the regression on both hikey running AOSP
> and User Mode Linux running Debian.

Thanks for letting me know, I'll update the changelog a bit. How far
back does this patch need to go in stable kernel releases?

thanks,

greg k-h

2017-04-06 17:25:43

by Greg Hackmann

Subject: Re: [PATCH] staging: android: ashmem: lseek failed due to no FMODE_LSEEK.

On 04/06/2017 10:08 AM, Greg KH wrote:
> On Thu, Apr 06, 2017 at 08:30:40AM -0700, Greg Hackmann wrote:
>> On 04/06/2017 07:30 AM, [email protected] wrote:
>>> From: zhangshuxiao <[email protected]>
>>>
>>> vfs_llseek will check whether the file mode has
>>> FMODE_LSEEK, no return failure. But ashmem can be
>>> lseek, so add FMODE_LSEEK to ashmem file.
>>>
>>> Signed-off-by: Shuxiao Zhang <[email protected]>
>>> Tested-by: Greg Hackmann <[email protected]>
>>> ---
>>> drivers/staging/android/ashmem.c | 1 +
>>> 1 file changed, 1 insertion(+)
>>>
>>> diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c
>>> index 3f11332..e4530ac 100644
>>> --- a/drivers/staging/android/ashmem.c
>>> +++ b/drivers/staging/android/ashmem.c
>>> @@ -392,6 +392,7 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
>>> ret = PTR_ERR(vmfile);
>>> goto out;
>>> }
>>> + vmfile->f_mode |= FMODE_LSEEK;
>>> asma->file = vmfile;
>>> }
>>> get_file(asma->file);
>>>
>>
>> This commit message is missing some important context.
>>
>> ashmem_llseek() passes the llseek() call through to the backing shmem file.
>> 91360b02ab48 ("ashmem: use vfs_llseek()") changed this from directly calling
>> the file's llseek() op into a VFS layer call. This also adds a check for
>> the FMODE_LSEEK bit, so without that bit ashmem_llseek() now always fails
>> with -ESPIPE.
>>
>> I've tested that this patch fixes the regression on both hikey running AOSP
>> and User Mode Linux running Debian.
>
> Thanks for letting me know, I'll update the changelog a bit. How far
> back does this patch need to go in stable kernel releases?
>
> thanks,
>
> greg k-h
>

3.18 and later.