From fcc5a03ac42564e9e255c1134dda47442289e466 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Mon, 30 Jul 2007 17:03:38 -0700 Subject: [NET]: Allow netdev REGISTER/CHANGENAME events to fail This patch adds code to allow errors to be passed up from event handlers of NETDEV_REGISTER and NETDEV_CHANGENAME. It also adds the notifier_from_errno/notifier_to_errnor helpers to pass the errno value up to the notifier caller. If an error is detected when a device is registered, it causes that operation to fail. A NETDEV_UNREGISTER will be sent to all event handlers. Similarly if NETDEV_CHANGENAME fails the original name is restored and a new NETDEV_CHANGENAME event is sent. As such all event handlers must be idempotent with respect to these events. When an event handler is registered NETDEV_REGISTER events are sent for all devices currently registered. Should any of them fail, we will send NETDEV_GOING_DOWN/NETDEV_DOWN/NETDEV_UNREGISTER events to that handler for the devices which have already been registered with it. The handler registration itself will fail. Signed-off-by: Herbert Xu Signed-off-by: David S. Miller --- include/linux/notifier.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'include/linux/notifier.h') diff --git a/include/linux/notifier.h b/include/linux/notifier.h index be3f2bb6fcf3..fad7ff17e468 100644 --- a/include/linux/notifier.h +++ b/include/linux/notifier.h @@ -157,6 +157,19 @@ extern int __srcu_notifier_call_chain(struct srcu_notifier_head *nh, */ #define NOTIFY_STOP (NOTIFY_OK|NOTIFY_STOP_MASK) +/* Encapsulate (negative) errno value (in particular, NOTIFY_BAD <=> EPERM). */ +static inline int notifier_from_errno(int err) +{ + return NOTIFY_STOP_MASK | (NOTIFY_OK - err); +} + +/* Restore (negative) errno value from notify return value. */ +static inline int notifier_to_errno(int ret) +{ + ret &= ~NOTIFY_STOP_MASK; + return ret > NOTIFY_OK ? NOTIFY_OK - ret : 0; +} + /* * Declared notifiers so far. I can imagine quite a few more chains * over time (eg laptop power reset chains, reboot chain (to clean -- cgit v1.2.3