signal: support CLONE_PIDFD with pidfd_send_signal

Let pidfd_send_signal() use pidfds retrieved via CLONE_PIDFD.  With this
patch pidfd_send_signal() becomes independent of procfs.  This fullfils
the request made when we merged the pidfd_send_signal() patchset.  The
pidfd_send_signal() syscall is now always available allowing for it to
be used by users without procfs mounted or even users without procfs
support compiled into the kernel.

Signed-off-by: Christian Brauner <[email protected]>
Co-developed-by: Jann Horn <[email protected]>
Signed-off-by: Jann Horn <[email protected]>
Acked-by: Oleg Nesterov <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: "Eric W. Biederman" <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: David Howells <[email protected]>
Cc: "Michael Kerrisk (man-pages)" <[email protected]>
Cc: Andy Lutomirsky <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Aleksa Sarai <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Al Viro <[email protected]>

0 files changed, 0 insertions, 0 deletions