On Sun, Jan 31, 2010 at 05:20:55AM +0100, Arnd Bergmann wrote:
> On Sunday 31 January 2010, John Kacur wrote:
> > > Sorry, I should have been clearer, but not implementing llseek
> > > is the problem I was referring to: When a driver has no explicit
> > > .llseek operation in its file operations and does not call
> > > nonseekable_open from its open operation, the VFS layer will
> > > implicitly use default_llseek, which takes the BKL. We're
> > > in the process of changing drivers not to do this, one by one
> > > so we can kill the BKL in the end.
> > >
> >
> > I know we've discussed this before, but why wouldn't the following
> > make more sense?
> > .llseek = no_llseek,
>
> That's one of the possible solutions. Assigning it to generic_file_llseek
> also gets rid of the BKL but keeps the current behaviour (calling seek
> returns success without having an effect, no_llseek returns -ESPIPE),
> while calling nonseekable_open has the other side-effect of making
> pread/pwrite fail with -ESPIPE, which is more consistent than
> only failing seek.
>
OK, so how about the patch below (on top of Thadeu's patch)?
--
Dmitry
Input: uinput - use nonseekable_open
Seeking does not make sense for uinput so let's use nonseekable_open
to mark the device non-seekable.
Signed-off-by: Dmitry Torokhov <dtor@xxxxxxx>
---
drivers/input/misc/uinput.c | 7 +++++++
1 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c
index 18206e1..7089151 100644
--- a/drivers/input/misc/uinput.c
+++ b/drivers/input/misc/uinput.c
@@ -278,6 +278,7 @@ static int uinput_create_device(struct uinput_device *udev)
static int uinput_open(struct inode *inode, struct file *file)
{
struct uinput_device *newdev;
+ int error;
newdev = kzalloc(sizeof(struct uinput_device), GFP_KERNEL);
if (!newdev)
@@ -291,6 +292,12 @@ static int uinput_open(struct inode *inode, struct file *file)
file->private_data = newdev;
+ error = nonseekable_open(inode, file);
+ if (error) {
+ kfree(newdev);
+ return error;
+ }
+
return 0;
}
--
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