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. 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. So we already correctly error out since we detect that it is an O_PATH before fdget_raw(). This just takes the opportunity to fix it. Christian
