On Wed, Dec 09, 2020 at 07:49:38PM +0000, Matthew Wilcox wrote:
> On Wed, Dec 09, 2020 at 12:04:38PM -0600, Eric W. Biederman wrote:
> > @@ -397,8 +397,9 @@ static struct fdtable *close_files(struct files_struct
> > * files)
> > set = fdt->open_fds[j++];
> > while (set) {
> > if (set & 1) {
> > - struct file * file = xchg(&fdt->fd[i], NULL);
> > + struct file * file = fdt->fd[i];
> > if (file) {
> > + rcu_assign_pointer(fdt->fd[i], NULL);
>
> Assuming this is safe, you can use RCU_INIT_POINTER() here because you're
> storing NULL, so you don't need the wmb() before storing the pointer.
fs/file.c:pick_file() would make more interesting target for the same
treatment...
