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, zhangshuxiaomi@xxxxxxxxx wrote:
From: zhangshuxiao <zhangshuxiao@xxxxxxxxxx>
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 <zhangshuxiao@xxxxxxxxxx>
Tested-by: Greg Hackmann <ghackmann@xxxxxxxxxx>
---
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.
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