On Mon, Dec 11, 2023 at 03:34:40PM +0000, Alice Ryhl wrote:
> Benno Lossin <benno.lossin@xxxxxxxxx> writes:
> > On 12/6/23 12:59, Alice Ryhl wrote:
> > > + /// Schedule a task work that closes the file descriptor when this task returns to userspace.
> > > + ///
> > > + /// Fails if this is called from a context where we cannot run work when returning to
> > > + /// userspace. (E.g., from a kthread.)
> > > + pub fn close_fd(self, fd: u32) -> Result<(), DeferredFdCloseError> {
> > > + use bindings::task_work_notify_mode_TWA_RESUME as TWA_RESUME;
> > > +
> > > + // In this method, we schedule the task work before closing the file. This is because
> > > + // scheduling a task work is fallible, and we need to know whether it will fail before we
> > > + // attempt to close the file.
> > > +
> > > + // SAFETY: Getting a pointer to current is always safe.
> > > + let current = unsafe { bindings::get_current() };
> > > +
> > > + // SAFETY: Accessing the `flags` field of `current` is always safe.
> > > + let is_kthread = (unsafe { (*current).flags } & bindings::PF_KTHREAD) != 0;
> >
> > Since Boqun brought to my attention that we already have a wrapper for
> > `get_current()`, how about you use it here as well?
>
> I can use the wrapper, but it seems simpler to not go through a
> reference when we just need a raw pointer.
>
> Perhaps we should have a safe `Task::current_raw` function that just
> returns a raw pointer? It can still be safe.
>
I think we can have a `as_ptr` function for `Task`?
impl Task {
pub fn as_ptr(&self) -> *mut bindings::task_struct {
self.0.get()
}
}
Regards,
Boqun
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