[src/trunk]: src/sys Add support for unblocking read/write when close called.

[dsl <dsl%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/fd01c0c24814
branches:  trunk
changeset: 749917:fd01c0c24814
user:      dsl <dsl%NetBSD.org@localhost>
date:      Sat Dec 12 21:28:04 2009 +0000

description:
Add support for unblocking read/write when close called.
Fixes PR/26567 for pipes.
(NB ad backed out the fix for sockets)

diffstat:

 sys/kern/sys_pipe.c |  33 +++++++++++++++++++++++++++++----
 sys/sys/pipe.h      |   3 ++-
 2 files changed, 31 insertions(+), 5 deletions(-)

diffs (100 lines):

diff -r a039413eeae4 -r fd01c0c24814 sys/kern/sys_pipe.c
--- a/sys/kern/sys_pipe.c       Sat Dec 12 17:48:54 2009 +0000
+++ b/sys/kern/sys_pipe.c       Sat Dec 12 21:28:04 2009 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: sys_pipe.c,v 1.122 2009/12/10 20:55:17 dsl Exp $       */
+/*     $NetBSD: sys_pipe.c,v 1.123 2009/12/12 21:28:04 dsl Exp $       */
 
 /*-
  * Copyright (c) 2003, 2007, 2008, 2009 The NetBSD Foundation, Inc.
@@ -68,7 +68,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sys_pipe.c,v 1.122 2009/12/10 20:55:17 dsl Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sys_pipe.c,v 1.123 2009/12/12 21:28:04 dsl Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -109,6 +109,7 @@
 static int     pipe_kqfilter(file_t *, struct knote *);
 static int     pipe_stat(file_t *, struct stat *);
 static int     pipe_ioctl(file_t *, u_long, void *);
+static void    pipe_abort(file_t *);
 
 static const struct fileops pipeops = {
        .fo_read = pipe_read,
@@ -119,7 +120,7 @@
        .fo_stat = pipe_stat,
        .fo_close = pipe_close,
        .fo_kqfilter = pipe_kqfilter,
-       .fo_abort = fnullop_abort,
+       .fo_abort = pipe_abort,
 };
 
 /*
@@ -541,8 +542,12 @@
                 * Detect EOF condition.
                 * Read returns 0 on EOF, no need to set error.
                 */
-               if (rpipe->pipe_state & PIPE_EOF)
+               if (rpipe->pipe_state & (PIPE_EOF | PIPE_ABORTED)) {
+                       if (rpipe->pipe_state & PIPE_ABORTED)
+                               /* Another thread has called close() */
+                               error = EBADF;
                        break;
+               }
 
                /*
                 * Don't block on non-blocking I/O.
@@ -979,6 +984,13 @@
                                break;
                        }
 
+                       if (wpipe->pipe_state & PIPE_ABORTED) {
+                               /* Another thread has called close() */
+                               if (uio->uio_resid == 0)
+                                       error = EBADF;
+                               break;
+                       }
+
                        /*
                         * We have no more space and have something to offer,
                         * wake up select/poll.
@@ -1204,6 +1216,19 @@
 }
 
 static void
+pipe_abort(file_t *fp)
+{
+       struct pipe *pipe = fp->f_data;
+
+       /* Unblock blocked reads/writes - they will return EBADF. */
+       mutex_enter(pipe->pipe_lock);
+       pipe->pipe_state |= PIPE_ABORTED;
+       cv_broadcast(&pipe->pipe_rcv);
+       cv_broadcast(&pipe->pipe_wcv);
+       mutex_exit(pipe->pipe_lock);
+}
+
+static void
 pipe_free_kmem(struct pipe *pipe)
 {
 
diff -r a039413eeae4 -r fd01c0c24814 sys/sys/pipe.h
--- a/sys/sys/pipe.h    Sat Dec 12 17:48:54 2009 +0000
+++ b/sys/sys/pipe.h    Sat Dec 12 21:28:04 2009 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: pipe.h,v 1.29 2009/11/26 16:18:37 pooka Exp $ */
+/* $NetBSD: pipe.h,v 1.30 2009/12/12 21:28:04 dsl Exp $ */
 
 /*
  * Copyright (c) 1996 John S. Dyson
@@ -96,6 +96,7 @@
                                   pointers/data. */
 #define        PIPE_LWANT      0x200   /* Process wants exclusive access to
                                   pointers/data. */
+#define        PIPE_ABORTED    0x400   /* fo_abort()ed, unblock read/write */
 
 /*
  * Per-pipe data structure.