sigaction.2: Clarify description of SA_NODEFER

Clarify description of SA_NODEFER, and note interaction with
act.sa_mask.

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

diff --git a/man2/sigaction.2 b/man2/sigaction.2
index 72c3565f92059adfc3c037b41849c9ed0db10a83..8e83da85b90cd7c788c077385a6b44a2a4dfc5ae 100644 (file)
--- a/man2/sigaction.2
+++ b/man2/sigaction.2
@@ -204,9 +204,11 @@ signal is generated in this case;
 on some other implementations, it is not.
 .TP
 .B SA_NODEFER
-Do not prevent the signal from being received from within its own signal
-handler (i.e., do not add the signal to the thread's signal mask while the
-handler is executing).
+Do not add the signal to the thread's signal mask while the
+handler is executing, unless the signal is specified in
+.IR act.sa_mask .
+Consequently, a further instance of the signal may be delivered
+to the thread while it is executing the handler.
 This flag is meaningful only when establishing a signal handler.
 .IP
 .B SA_NOMASK
@@ -1037,6 +1039,7 @@ prevents not only the delivered signal from being masked during
 execution of the handler, but also the signals specified in
 .IR sa_mask .
 This bug was fixed in kernel 2.6.14.
+.\" commit 69be8f189653cd81aae5a74e26615b12871bb72e
 .SH EXAMPLES
 See
 .BR mprotect (2).