Re: [PATCH] staging: android: ashmem: Declared file operation with const keyword Warning found by checkpatch.pl script.

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Mon, Mar 14, 2022 at 04:55:55PM +0530, shaikh kamaluddin wrote:
> On 3/13/2022 3:13 AM, Pavel Skripkin wrote:
> > Hi Shaikh,
> > 
> > On 3/12/22 23:41, shaikh kamal wrote:
> > > Signed-off-by: shaikh kamal <shaikhkamal2012@gmail.com>
> > > ---
> > >   drivers/staging/android/ashmem.c | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/staging/android/ashmem.c
> > > b/drivers/staging/android/ashmem.c
> > > index ddbde3f8430e..4c6b420fbf4d 100644
> > > --- a/drivers/staging/android/ashmem.c
> > > +++ b/drivers/staging/android/ashmem.c
> > > @@ -377,7 +377,7 @@ ashmem_vmfile_get_unmapped_area(struct file
> > > *file, unsigned long addr,
> > >   static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
> > >   {
> > > -    static struct file_operations vmfile_fops;
> > > +    static const struct file_operations vmfile_fops;
> > >       struct ashmem_area *asma = file->private_data;
> > >       int ret = 0;
> > 
> > Are you sure this patch compiles? vmfile_fops is overrided few lines below
> > 
> > odd checkpatch.pl warning...
> > 
> > 
> > 
> > 
> > With regards,
> > Pavel Skripkin
> 
> Thank you,yes vmfile_fops is overrided in below code.
> Building the kernel - make -j4,
> drivers/staging/android/ashmem.c: In function ‘ashmem_mmap’:
> drivers/staging/android/ashmem.c:431:16: error: assignment of read-only
> variable ‘vmfile_fops’
>     vmfile_fops = *vmfile->f_op;
>                 ^
> drivers/staging/android/ashmem.c:432:21: error: assignment of member ‘mmap’
> in read-only object
>     vmfile_fops.mmap = ashmem_vmfile_mmap;
>                      ^
> drivers/staging/android/ashmem.c:433:34: error: assignment of member
> ‘get_unmapped_area’ in read-only object
>     vmfile_fops.get_unmapped_area =
>                                   ^
> scripts/Makefile.build:288: recipe for target
> 'drivers/staging/android/ashmem.o' failed
> make[3]: *** [drivers/staging/android/ashmem.o] Error 1
> scripts/Makefile.build:550: recipe for target 'drivers/staging/android'
> failed
> make[2]: *** [drivers/staging/android] Error 2
> scripts/Makefile.build:550: recipe for target 'drivers/staging' failed
> make[1]: *** [drivers/staging] Error 2
> Makefile:1831: recipe for target 'drivers' failed

As always, it is expected that when you submit a change to the kernel,
at the very least you have test-built it to ensure that it does not
break the build.  Please remember to do this next time.

thanks,

greg k-h