On Thu, 2019-01-03 at 14:27 +1100, Benjamin Herrenschmidt wrote: > On Wed, 2019-01-02 at 09:34 +0000, David Howells wrote: > > Jia-Ju Bai <baijiaju1...@gmail.com> wrote: > > > > > + mutex_lock(&user->file_lock); > > > sbefifo_release_command(user); > > > free_page((unsigned long)user->cmd_page); > > > + mutex_unlock(&user->file_lock); > > > > It shouldn't be necessary to do the free_page() call inside the locked > > section. > > True. However, I didn't realize read/write could be concurrent with > release so we have another problem. > > I assume when release is called, no new read/write can be issued, I am > correct ? So all we have to protect against is a read/write that has > started prior to release being called, right ?
Hrm... looking briefly at the vfs, read/write are wrapped in fdget/fdput, so release shouldn't happen concurrently or am I missing something here ? Cheers, Ben.
