sched/signal: In signal notification facility, use sigqueue() to notify vs. kill(). With sigqueue, we can pass more info (but still not enough).

net/netdev/netdown_notifier.c

@@ -0,0 +1,153 @@
+/****************************************************************************
+ * net/netdev/netdown_notifier.c
+ *
+ *   Copyright (C) 2018 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+
+#include <nuttx/signal.h>
+#include <nuttx/mm/iob.h>
+#include <nuttx/net/netdev.h>
+
+#include "netdev/netdev.h"
+
+#ifdef CONFIG_NETDOWN_NOTIFIER
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: netdown_notifier_setup
+ *
+ * Description:
+ *   Set up to notify the specified PID with the provided signal number.
+ *
+ *   NOTE: To avoid race conditions, the caller should set the sigprocmask
+ *   to block signal delivery.  The signal will be delivered once the
+ *   signal is removed from the sigprocmask.
+ *
+ * Input Parameters:
+ *   pid   - The PID to be notified.  If a zero value is provided, then the
+ *           PID of the calling thread will be used.
+ *   signo - The signal number to use with the notification.
+ *   dev   - The network driver to be monitored
+ *
+ * Returned Value:
+ *   > 0   - The signal notification is in place.  The returned value is a
+ *           key that may be used later in a call to
+ *           netdown_notifier_teardown().
+ *   == 0  - The the device is already down.  No signal notification will
+ *           be provided.
+ *   < 0   - An unexpected error occurred and no signal will be sent.  The
+ *           returned value is a negated errno value that indicates the
+ *           nature of the failure.
+ *
+ ****************************************************************************/
+
+int netdown_notifier_setup(int pid, int signo, FAR struct net_driver_s *dev)
+{
+  /* If network driver is already down, then return zero without setting up
+   * the notification.
+   */
+
+  if ((dev->d_flags & IFF_UP) == 0)
+    {
+      return 0;
+    }
+
+  /* Otherwise, this is just a simple wrapper around nxsig_notifer_setup(). */
+
+  return nxsig_notifier_setup(pid, signo, NXSIG_NET_DOWN, dev);
+}
+
+/****************************************************************************
+ * Name: netdown_notifier_teardown
+ *
+ * Description:
+ *   Eliminate a TCP read-ahead notification previously setup by
+ *   netdown_notifier_setup().  This function should only be called if the
+ *   notification should be aborted prior to the notification.  The
+ *   notification will automatically be torn down after the signal is sent.
+ *
+ * Input Parameters:
+ *   key - The key value returned from a previous call to
+ *         netdown_notifier_setup().
+ *
+ * Returned Value:
+ *   Zero (OK) is returned on success; a negated errno value is returned on
+ *   any failure.
+ *
+ ****************************************************************************/
+
+int netdown_notifier_teardown(int key)
+{
+  /* This is just a simple wrapper around nxsig_notifier_teardown(). */
+
+  return nxsig_notifier_teardown(key);
+}
+
+/****************************************************************************
+ * Name: netdown_notifier_signal
+ *
+ * Description:
+ *   Read-ahead data has been buffered.  Signal all threads waiting for
+ *   read-ahead data to become available.
+ *
+ *   When the read-ahead data becomes available, *all* of the waiters in
+ *   this thread will be signaled.  If there are multiple waiters then only
+ *   the highest priority thread will get the data.  Lower priority threads
+ *   will need to call netdown_notifier_setup() once again.
+ *
+ * Input Parameters:
+ *   dev  - The TCP connection where read-ahead data was just buffered.
+ *
+ * Returned Value:
+ *   None.
+ *
+ ****************************************************************************/
+
+void netdown_notifier_signal(FAR struct net_driver_s *dev)
+{
+  /* This is just a simple wrapper around nxsig_notifier_signal(). */
+
+  return nxsig_notifier_signal(NXSIG_NET_DOWN, dev);
+}
+
+#endif /* CONFIG_NETDOWN_NOTIFIER */