On Wed, 2011-10-26 at 10:19 -0700, Andres Salomon wrote:
> Commit 2e30168b ("libertas: terminate scan when stopping interface")
> adds cleanup code to lbs_eth_stop to call cfg80211_scan_done if there's
> an outstanding cfg80211_scan_request. However, it assumes that the
> scan request was allocated via the cfg80211 stack. Libertas has
> its own internal allocation method, kept track of with
> priv->internal_scan. This doesn't set scan_req->wiphy, amongst other
> things, which results in hitting a BUG() when we call cfg80211_scan_done
> on the request.
>
> This provides a function to take care of the low-level scan_req cleanup
> details. We simply call that to deal with finishing up scan requests.
Acked-by: Dan Williams <dcbw@xxxxxxxxxx>
> The bug we were hitting was:
>
> [ 964.321495] kernel BUG at net/wireless/core.h:87!
> [ 964.329970] Unable to handle kernel NULL pointer dereference at virtual address 00000000
> [ 964.341963] pgd = dcf80000
> ...
> [ 964.849998] 9fe0: 00000000 beb417b8 4018e280 401e822c 60000010 00000004 00000000 00000000
> [ 964.865007] [<c003104c>] (__bug+0x1c/0x28) from [<c0384ffc>] (cfg80211_scan_done+0x54/0x6c)
> [ 964.895324] [<c0384ffc>] (cfg80211_scan_done+0x54/0x6c) from [<bf028bac>] (lbs_eth_stop+0x10c/0x188 [libertas])
> [ 964.895324] [<bf028bac>] (lbs_eth_stop+0x10c/0x188 [libertas]) from [<c03002a0>] (__dev_close_many+0x94/0xc4)
> [ 964.918995] [<c03002a0>] (__dev_close_many+0x94/0xc4) from [<c030037c>] (dev_close_many+0x78/0xe0)
>
> Signed-off-by: Andres Salomon <dilinger@xxxxxxxxxx>
> ---
> drivers/net/wireless/libertas/cfg.c | 25 +++++++++++++++++--------
> drivers/net/wireless/libertas/cfg.h | 1 +
> drivers/net/wireless/libertas/main.c | 6 ++----
> 3 files changed, 20 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/net/wireless/libertas/cfg.c b/drivers/net/wireless/libertas/cfg.c
> index ff63782..4fcd653 100644
> --- a/drivers/net/wireless/libertas/cfg.c
> +++ b/drivers/net/wireless/libertas/cfg.c
> @@ -728,15 +728,9 @@ static void lbs_scan_worker(struct work_struct *work)
> le16_to_cpu(scan_cmd->hdr.size),
> lbs_ret_scan, 0);
>
> - if (priv->scan_channel >= priv->scan_req->n_channels) {
> + if (priv->scan_channel >= priv->scan_req->n_channels)
> /* Mark scan done */
> - if (priv->internal_scan)
> - kfree(priv->scan_req);
> - else
> - cfg80211_scan_done(priv->scan_req, false);
> -
> - priv->scan_req = NULL;
> - }
> + lbs_scan_done(priv);
>
> /* Restart network */
> if (carrier)
> @@ -774,6 +768,21 @@ static void _internal_start_scan(struct lbs_private *priv, bool internal,
> lbs_deb_leave(LBS_DEB_CFG80211);
> }
>
> +/*
> + * Clean up priv->scan_req. Should be used to handle the allocation details.
> + */
> +void lbs_scan_done(struct lbs_private *priv)
> +{
> + WARN_ON(!priv->scan_req);
> +
> + if (priv->internal_scan)
> + kfree(priv->scan_req);
> + else
> + cfg80211_scan_done(priv->scan_req, false);
> +
> + priv->scan_req = NULL;
> +}
> +
> static int lbs_cfg_scan(struct wiphy *wiphy,
> struct net_device *dev,
> struct cfg80211_scan_request *request)
> diff --git a/drivers/net/wireless/libertas/cfg.h b/drivers/net/wireless/libertas/cfg.h
> index a02ee15..558168c 100644
> --- a/drivers/net/wireless/libertas/cfg.h
> +++ b/drivers/net/wireless/libertas/cfg.h
> @@ -16,6 +16,7 @@ int lbs_reg_notifier(struct wiphy *wiphy,
> void lbs_send_disconnect_notification(struct lbs_private *priv);
> void lbs_send_mic_failureevent(struct lbs_private *priv, u32 event);
>
> +void lbs_scan_done(struct lbs_private *priv);
> void lbs_scan_deinit(struct lbs_private *priv);
> int lbs_disconnect(struct lbs_private *priv, u16 reason);
>
> diff --git a/drivers/net/wireless/libertas/main.c b/drivers/net/wireless/libertas/main.c
> index b03779b..39a6a7a 100644
> --- a/drivers/net/wireless/libertas/main.c
> +++ b/drivers/net/wireless/libertas/main.c
> @@ -255,10 +255,8 @@ static int lbs_eth_stop(struct net_device *dev)
>
> lbs_update_mcast(priv);
> cancel_delayed_work_sync(&priv->scan_work);
> - if (priv->scan_req) {
> - cfg80211_scan_done(priv->scan_req, false);
> - priv->scan_req = NULL;
> - }
> + if (priv->scan_req)
> + lbs_scan_done(priv);
>
> netif_carrier_off(priv->dev);
>
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