This patch modifies wext adding a flag that allows drivers to specify that
they do not wish their wext calls made under rtnl. The default is to still
acquire the rtnl.
Warning: a device reference is held for the new no_locking API,
therefore it is not safe to call unregister_netdev on the passed device!
Signed-off-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
---
include/net/iw_handler.h | 3 +
net/wireless/wext-common.c | 6 --
net/wireless/wext-old.c | 127 ++++++++++++++++++++++++---------------------
3 files changed, 72 insertions(+), 64 deletions(-)
--- wireless-dev.orig/include/net/iw_handler.h 2007-04-13 23:20:56.755356880 +0200
+++ wireless-dev/include/net/iw_handler.h 2007-04-13 23:36:48.635356880 +0200
@@ -349,6 +349,9 @@ struct iw_handler_def
* The old pointer in struct net_device will be gradually phased
* out, and drivers are encouraged to use this one... */
struct iw_statistics* (*get_wireless_stats)(struct net_device *dev);
+
+ /* can live without rtnl locking? */
+ int no_locking;
};
/* ---------------------- IOCTL DESCRIPTION ---------------------- */
--- wireless-dev.orig/net/wireless/wext-common.c 2007-04-13 23:20:56.785356880 +0200
+++ wireless-dev/net/wireless/wext-common.c 2007-04-13 23:36:48.635356880 +0200
@@ -631,15 +631,9 @@ int wext_ioctl(unsigned int cmd, struct
#ifdef CONFIG_WIRELESS_EXT
dev_load(ifr->ifr_name);
- /* we could change the code to not hold the rtnl but
- * some callees might require it held */
- rtnl_lock();
-
/* Follow me in wext-old.c */
ret = wireless_process_ioctl(ifr, cmd);
- rtnl_unlock();
-
/* haha, I cheat here by allowing a driver or stack to have both WE and
* CFG80211-WE for a little while during conversion... wext returns
* -EOPNOTSUPP if a handler is not assigned, so we can in that case try
--- wireless-dev.orig/net/wireless/wext-old.c 2007-04-13 23:20:56.925356880 +0200
+++ wireless-dev/net/wireless/wext-old.c 2007-04-17 17:45:57.752028444 +0200
@@ -516,74 +516,85 @@ static inline int ioctl_private_call(str
return ret;
}
-/* ---------------------------------------------------------------- */
+static int ioctl_call(struct net_device *dev, struct ifreq *ifr,
+ unsigned int cmd, iw_handler handler)
+{
+ /* Standard and private are not the same */
+ if (cmd >= SIOCIWFIRSTPRIV)
+ return ioctl_private_call(dev, ifr, cmd, handler);
+
+ return ioctl_standard_call(dev, ifr, cmd, handler);
+}
+
+static int dev_process_ioctl(struct net_device *dev, struct ifreq *ifr,
+ unsigned int cmd)
+{
+ iw_handler handler;
+
+ if (cmd == SIOCGIWSTATS) {
+ /* Get Wireless Stats */
+ return ioctl_standard_call(dev, ifr, cmd,
+ &iw_handler_get_iwstats);
+ }
+
+ if (cmd == SIOCGIWPRIV && dev->wireless_handlers) {
+ /* We export to user space the definition of
+ * the private handler ourselves */
+ return ioctl_standard_call(dev, ifr, cmd,
+ &iw_handler_get_private);
+ }
+
+ /* Basic check */
+ if (!netif_device_present(dev))
+ return -ENODEV;
+
+ /* New driver API : try to find the handler */
+ handler = get_handler(dev, cmd);
+ if (handler)
+ return ioctl_call(dev, ifr, cmd, handler);
+
+ /* Old driver API : call driver ioctl handler */
+ if (dev->do_ioctl)
+ return dev->do_ioctl(dev, ifr, cmd);
+
+ return -EOPNOTSUPP;
+}
+
/*
- * Main IOCTl dispatcher. Called from the main networking code
- * (dev_ioctl() in net/core/dev.c).
- * Check the type of IOCTL and call the appropriate wrapper...
+ * Main ioctl dispatcher. Called from the common wireless code
+ * in net/wireless/wext-common.c.
*/
int wireless_process_ioctl(struct ifreq *ifr, unsigned int cmd)
{
struct net_device *dev;
- iw_handler handler;
+ int err;
- /* Permissions are already checked in dev_ioctl() before calling us.
- * The copy_to/from_user() of ifr is also dealt with in there */
+ /* Get device reference so it doesn't go away */
+ dev = dev_get_by_name(ifr->ifr_name);
- /* Make sure the device exist */
- if ((dev = __dev_get_by_name(ifr->ifr_name)) == NULL)
+ if (!dev)
return -ENODEV;
- /* A bunch of special cases, then the generic case...
- * Note that 'cmd' is already filtered in dev_ioctl() with
- * (cmd >= SIOCIWFIRST && cmd <= SIOCIWLAST) */
- switch(cmd) {
- case SIOCGIWSTATS:
- /* Get Wireless Stats */
- return ioctl_standard_call(dev,
- ifr,
- cmd,
- &iw_handler_get_iwstats);
-
- case SIOCGIWPRIV:
- /* Check if we have some wireless handlers defined */
- if(dev->wireless_handlers != NULL) {
- /* We export to user space the definition of
- * the private handler ourselves */
- return ioctl_standard_call(dev,
- ifr,
- cmd,
- &iw_handler_get_private);
- }
- // ## Fall-through for old API ##
- default:
- /* Generic IOCTL */
- /* Basic check */
- if (!netif_device_present(dev))
- return -ENODEV;
- /* New driver API : try to find the handler */
- handler = get_handler(dev, cmd);
- if(handler != NULL) {
- /* Standard and private are not the same */
- if(cmd < SIOCIWFIRSTPRIV)
- return ioctl_standard_call(dev,
- ifr,
- cmd,
- handler);
- else
- return ioctl_private_call(dev,
- ifr,
- cmd,
- handler);
- }
- /* Old driver API : call driver ioctl handler */
- if (dev->do_ioctl) {
- return dev->do_ioctl(dev, ifr, cmd);
- }
- return -EOPNOTSUPP;
+ /*
+ * Check for the new no_locking API and if no locking is wanted then
+ * call the handler without ever touching rtnl.
+ * It needs to be this way to avoid ABBA type deadlocks.
+ */
+ if (dev->wireless_handlers && dev->wireless_handlers->no_locking) {
+ err = dev_process_ioctl(dev, ifr, cmd);
+ dev_put(dev);
+ } else {
+ rtnl_lock();
+ /*
+ * put device before calling handler, it might expect a
+ * device with no held references in its own call path.
+ */
+ dev_put(dev);
+ err = dev_process_ioctl(dev, ifr, cmd);
+ rtnl_unlock();
}
- /* Not reached */
- return -EINVAL;
+
+ return err;
}
/********************** ENHANCED IWSPY SUPPORT **********************/
-
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