mac80211: fix deadlocks in debugfs_netdev.c

The bug shows up with CONFIG_PREEMPT enabled. Pointed out by Andrew Morton.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Luis Carlos Cobo <luisca@cozybit.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c
index 0e921ae..3e19d42 100644 (file)
--- a/net/mac80211/debugfs_netdev.c
+++ b/net/mac80211/debugfs_netdev.c
@@ -31,11 +31,13 @@ static ssize_t ieee80211_if_read(
        ssize_t ret = -EINVAL;
 
        read_lock(&dev_base_lock);
-       if (sdata->dev->reg_state == NETREG_REGISTERED) {
+       if (sdata->dev->reg_state == NETREG_REGISTERED)
                ret = (*format)(sdata, buf, sizeof(buf));
-               ret = simple_read_from_buffer(userbuf, count, ppos, buf, ret);
-       }
        read_unlock(&dev_base_lock);
+
+       if (ret != -EINVAL)
+               ret = simple_read_from_buffer(userbuf, count, ppos, buf, ret);
+
        return ret;
 }
 
@@ -51,13 +53,13 @@ static ssize_t ieee80211_if_write(
 
        memset(buf, 0x00, sizeof(buf));
        buf_size = min(count, (sizeof(buf)-1));
-       read_lock(&dev_base_lock);
        if (copy_from_user(buf, userbuf, buf_size))
-               goto endwrite;
+               return count;
+       read_lock(&dev_base_lock);
        if (sdata->dev->reg_state == NETREG_REGISTERED)
                (*format)(sdata, buf);
-endwrite:
        read_unlock(&dev_base_lock);
+
        return count;
 }
 #endif