signal.7: Add reference to seccomp_user_notif(2)

The seccomp user-space notification feature can cause changes in
the semantics of SA_RESTART with respect to system calls that
would never normally be restarted. Point the reader to the page
that provide further details.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

diff --git a/man7/signal.7 b/man7/signal.7
index 91669145a2d8e711ecfb1564a2570000fab8cd84..6995e28ed7dd8a613f2a1d7bb400b400c5561f55 100644 (file)
--- a/man7/signal.7
+++ b/man7/signal.7
@@ -742,6 +742,15 @@ The
 .BR sleep (3)
 function is also never restarted if interrupted by a handler,
 but gives a success return: the number of seconds remaining to sleep.
+.PP
+In certain circumstances, the
+.BR seccomp (2)
+user-space notification feature can lead to restarting of system calls
+that would otherwise never be restarted by
+.BR SA_RESTART ;
+for details, see
+.BR seccomp_user_notif (2).
+.\"
 .SS Interruption of system calls and library functions by stop signals
 On Linux, even in the absence of signal handlers,
 certain blocking interfaces can fail with the error