On Wed, 2011-12-07 at 21:58 +0530, Vasanthakumar Thiagarajan wrote:
> It is quite possible to run into a race in bss timeout where
> the drivers see the bss entry just before notifying cfg80211
> of a roaming event but it got timed out by the time rdev->event_work
> got scehduled from cfg80211_wq. This would result in the following
> WARN-ON() along with the failure to notify the user space of
> the roaming. The other situation which is happening with ath6kl
> that runs into issue is when the driver reports roam to same AP
> event where the AP bss entry already got expired. To fix this,
> move cfg80211_get_bss() from __cfg80211_roamed() to cfg80211_roamed().
>
> [158645.538384] WARNING: at net/wireless/sme.c:586
> __cfg80211_roamed+0xc2/0x1b1()
> [158645.538810] Call Trace:
> [158645.538838] [<c1033527>] warn_slowpath_common+0x65/0x7a
> [158645.538917] [<c14cfacf>] ? __cfg80211_roamed+0xc2/0x1b1
> [158645.538946] [<c103354b>] warn_slowpath_null+0xf/0x13
> [158645.539055] [<c14cfacf>] __cfg80211_roamed+0xc2/0x1b1
> [158645.539086] [<c14beb5b>] cfg80211_process_rdev_events+0x153/0x1cc
> [158645.539166] [<c14bd57b>] cfg80211_event_work+0x26/0x36
> [158645.539195] [<c10482ae>] process_one_work+0x219/0x38b
> [158645.539273] [<c14bd555>] ? wiphy_new+0x419/0x419
> [158645.539301] [<c10486cb>] worker_thread+0xf6/0x1bf
> [158645.539379] [<c10485d5>] ? rescuer_thread+0x1b5/0x1b5
> [158645.539407] [<c104b3e2>] kthread+0x62/0x67
> [158645.539484] [<c104b380>] ? __init_kthread_worker+0x42/0x42
> [158645.539514] [<c151309a>] kernel_thread_helper+0x6/0xd
>
> Reported-by: Kalle Valo <kvalo@xxxxxxxxxxxxxxxx>
> Signed-off-by: Vasanthakumar Thiagarajan <vthiagar@xxxxxxxxxxxxxxxx>
Reviewed-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
> @@ -624,32 +617,57 @@ void cfg80211_roamed(struct net_device *dev,
> const u8 *resp_ie, size_t resp_ie_len, gfp_t gfp)
> {
> struct wireless_dev *wdev = dev->ieee80211_ptr;
> + struct cfg80211_bss *bss;
> +
> + CFG80211_DEV_WARN_ON(wdev->sme_state != CFG80211_SME_CONNECTED);
> +
> + bss = cfg80211_get_bss(wdev->wiphy, channel, bssid, wdev->ssid,
> + wdev->ssid_len, WLAN_CAPABILITY_ESS,
> + WLAN_CAPABILITY_ESS);
> + if (WARN_ON(!bss))
> + return;
> +
> + cfg80211_roamed_bss(dev, bss, req_ie, req_ie_len, resp_ie,
> + resp_ie_len, gfp);
Technically, you don't need either of these warnings since you call
cfg80211_roamed_bss() which checks, but I don't really care or mind.
johannes
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