On 04/17, Christian Brauner wrote: > > On Wed, Apr 17, 2019 at 04:01:06PM +0200, Oleg Nesterov wrote: > > On 04/16, Christian Brauner wrote: > > > > > > @@ -3581,12 +3588,12 @@ SYSCALL_DEFINE4(pidfd_send_signal, int, pidfd, int, sig, > > > if (flags) > > > return -EINVAL; > > > > > > - f = fdget_raw(pidfd); > > > + f = fdget(pidfd); > > > > could you explain this change? > > > > I am just curious, I don't understand why should we disallow O_PATH and how > > this connects to this patch. > > Sending a signal through a pidfd is considered to be on a par with a > "write" to that pidfd. OK, but how this connects to "support pidfds" ? > Additionally, we use the fops associated with the fd to detect whether > it is actually a pidfd or not. This is not possible with O_PATH since > f_ops will be set to dummy fops. indeed... I didn't know this, thanks! But this means that pidfd_send_signal() will return -EBADF with or without this change; pidfd_to_pid() will return -EBADF even if fdget_raw() suceeds, right? To clarify, I am not arguing. I am trying to understand why exactly do we need this s/fdget_raw/fdget/ change and, why it doesn't come as a separate patch. Can you add a note into the changelog? Oleg.
