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cfg80211: fix deadlock with rfkill/sched_scan by adding new mutex

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There was a deadlock when rfkill-blocking a wireless interface,
because we were locking the rdev mutex on NETDEV_GOING_DOWN to stop
sched_scans that were eventually running.  The rfkill block code was
already holding a mutex under rdev:

kernel: =======================================================
kernel: [ INFO: possible circular locking dependency detected ]
kernel: 3.0.0-rc1-00049-g1fa7b6a #57
kernel: -------------------------------------------------------
kernel: kworker/0:1/4525 is trying to acquire lock:
kernel: (&rdev->mtx){+.+.+.}, at: [<ffffffff8164c831>] cfg80211_netdev_notifier_call+0x131/0x5b0
kernel:
kernel: but task is already holding lock:
kernel: (&rdev->devlist_mtx){+.+.+.}, at: [<ffffffff8164dcef>] cfg80211_rfkill_set_block+0x4f/0xa0
kernel:
kernel: which lock already depends on the new lock.

To fix this, add a new mutex specifically for sched_scan, to protect
the sched_scan_req element in the rdev struct, instead of using the
global rdev mutex.

Reported-by: Duane Griffin <duaneg@dghda.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Luciano Coelho
2011-06-30 08:32:41 +03:00
committed by John W. Linville
parent 37000b305b
commit c10841ca72
4 changed files with 34 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
net/wireless/nl80211.c
View File

@@ -3461,9 +3461,6 @@ static int nl80211_start_sched_scan(struct sk_buff *skb,
if (!is_valid_ie_attr(info->attrs[NL80211_ATTR_IE]))
return -EINVAL;
if (rdev->sched_scan_req)
return -EINPROGRESS;
if (!info->attrs[NL80211_ATTR_SCHED_SCAN_INTERVAL])
return -EINVAL;
@@ -3502,12 +3499,21 @@ static int nl80211_start_sched_scan(struct sk_buff *skb,
if (ie_len > wiphy->max_scan_ie_len)
return -EINVAL;
mutex_lock(&rdev->sched_scan_mtx);
if (rdev->sched_scan_req) {
err = -EINPROGRESS;
goto out;
}
request = kzalloc(sizeof(*request)
+ sizeof(*request->ssids) * n_ssids
+ sizeof(*request->channels) * n_channels
+ ie_len, GFP_KERNEL);
if (!request)
return -ENOMEM;
if (!request) {
err = -ENOMEM;
goto out;
}
if (n_ssids)
request->ssids = (void *)&request->channels[n_channels];
@@ -3605,6 +3611,7 @@ static int nl80211_start_sched_scan(struct sk_buff *skb,
out_free:
kfree(request);
out:
mutex_unlock(&rdev->sched_scan_mtx);
return err;
}
@@ -3612,12 +3619,17 @@ static int nl80211_stop_sched_scan(struct sk_buff *skb,
struct genl_info *info)
{
struct cfg80211_registered_device *rdev = info->user_ptr[0];
int err;
if (!(rdev->wiphy.flags & WIPHY_FLAG_SUPPORTS_SCHED_SCAN) ||
!rdev->ops->sched_scan_stop)
return -EOPNOTSUPP;
return __cfg80211_stop_sched_scan(rdev, false);
mutex_lock(&rdev->sched_scan_mtx);
err = __cfg80211_stop_sched_scan(rdev, false);
mutex_unlock(&rdev->sched_scan_mtx);
return err;
}
static int nl80211_send_bss(struct sk_buff *msg, u32 pid, u32 seq, int flags,