wext: let get_wireless_stats() sleep

Submitted by Johannes Berg on Oct. 5, 2009, 9:15 a.m.

Details

Message ID 1254734159.22426.6.camel@johannes.local
State Accepted
Delegated to: David Miller
Headers show

Commit Message

Johannes Berg Oct. 5, 2009, 9:15 a.m.
A number of drivers (recently including cfg80211-based ones)
assume that all wireless handlers, including statistics, can
sleep and they often also implicitly assume that the rtnl is
held around their invocation. This is almost always true now
except when reading from sysfs:

  BUG: sleeping function called from invalid context at kernel/mutex.c:280
  in_atomic(): 1, irqs_disabled(): 0, pid: 10450, name: head
  2 locks held by head/10450:
   #0:  (&buffer->mutex){+.+.+.}, at: [<c10ceb99>] sysfs_read_file+0x24/0xf4
   #1:  (dev_base_lock){++.?..}, at: [<c12844ee>] wireless_show+0x1a/0x4c
  Pid: 10450, comm: head Not tainted 2.6.32-rc3 #1
  Call Trace:
   [<c102301c>] __might_sleep+0xf0/0xf7
   [<c1324355>] mutex_lock_nested+0x1a/0x33
   [<f8cea53b>] wdev_lock+0xd/0xf [cfg80211]
   [<f8cea58f>] cfg80211_wireless_stats+0x45/0x12d [cfg80211]
   [<c13118d6>] get_wireless_stats+0x16/0x1c
   [<c12844fe>] wireless_show+0x2a/0x4c

Fix this by using the rtnl instead of dev_base_lock.

Reported-by: Miles Lane <miles.lane@gmail.com>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
---
 net/core/net-sysfs.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)



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Comments

David Miller Oct. 5, 2009, 9:22 a.m.
From: Johannes Berg <johannes@sipsolutions.net>
Date: Mon, 05 Oct 2009 11:15:59 +0200

> A number of drivers (recently including cfg80211-based ones)
> assume that all wireless handlers, including statistics, can
> sleep and they often also implicitly assume that the rtnl is
> held around their invocation. This is almost always true now
> except when reading from sysfs:
 ...
> Fix this by using the rtnl instead of dev_base_lock.
> 
> Reported-by: Miles Lane <miles.lane@gmail.com>
> Signed-off-by: Johannes Berg <johannes@sipsolutions.net>

Fair enough, applied, thanks!
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Patch hide | download patch | download mbox

--- wireless-testing.orig/net/core/net-sysfs.c	2009-10-05 11:09:56.000000000 +0200
+++ wireless-testing/net/core/net-sysfs.c	2009-10-05 11:10:52.000000000 +0200
@@ -366,13 +366,13 @@  static ssize_t wireless_show(struct devi
 	const struct iw_statistics *iw;
 	ssize_t ret = -EINVAL;
 
-	read_lock(&dev_base_lock);
+	rtnl_lock();
 	if (dev_isalive(dev)) {
 		iw = get_wireless_stats(dev);
 		if (iw)
 			ret = (*format)(iw, buf);
 	}
-	read_unlock(&dev_base_lock);
+	rtnl_unlock();
 
 	return ret;
 }