Minor improvements for tramp-interrupt-process, documentation

* doc/lispref/processes.texi (Signals to Processes):
* etc/NEWS: Document interrupt-process-functions.

* lisp/net/tramp.el (tramp-interrupt-process): Test also for
`process-live-p'.

* src/process.c (Vinterrupt_process_functions): Fix docstring.

* test/lisp/net/tramp-tests.el (tramp-test28-interrupt-process):
Extend test.

1 files changed, 16 insertions, 0 deletions

diff --git a/doc/lispref/processes.texi b/doc/lispref/processes.texi
index 292d55d50c5..45e04a5ab88 100644
--- a/doc/lispref/processes.texi
+++ b/doc/lispref/processes.texi
@@ -1351,6 +1351,22 @@ integer); that allows you to send signals to processes that are not
 children of Emacs.  @xref{System Processes}.
 @end deffn
 
+Sometimes, it is necessary to send a signal to a non-local
+asynchronous process.  This is possible by writing an own
+@code{interrupt-process} implementation.  This function must be added
+then to @code{interrupt-process-functions}.
+
+@defvar interrupt-process-functions
+This variable is a list of functions to be called for
+@code{interrupt-process}.  The arguments of the functions are the same
+as for @code{interrupt-process}.  These functions are called in the
+order of the list, until one of them returns non-@code{nil}.  The
+default function, which shall always be the last in this list, is
+@code{internal-default-interrupt-process}.
+
+This is the mechanism, how Tramp implements @code{interrupt-process}.
+@end defvar
+
 @node Output from Processes
 @section Receiving Output from Processes
 @cindex process output