brcmfmac: Check rtnl_lock is locked when removing interface

Check rtnl_lock is locked in brcmf_p2p_ifp_removed() by passing
rtnl_locked flag. Actually the caller brcmf_del_if() checks whether
the rtnl_lock is locked, but doesn't pass it to brcmf_p2p_ifp_removed().

Without this fix, wpa_supplicant goes softlockup with rtnl_lock
holding (this means all other process using netlink are locked up too)

e.g.
[ 4495.876627] INFO: task wpa_supplicant:7307 blocked for more than 10 seconds.
[ 4495.876632]       Tainted: G        W       4.8.0-rc1+ #8
[ 4495.876635] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 4495.876638] wpa_supplicant  D ffff974c647b39a0     0  7307      1 0x00000000
[ 4495.876644]  ffff974c647b39a0 0000000000000000 ffff974c00000000 ffff974c7dc59c58
[ 4495.876651]  ffff974c6b7417c0 ffff974c645017c0 ffff974c647b4000 ffffffff86f16c08
[ 4495.876657]  ffff974c645017c0 0000000000000246 00000000ffffffff ffff974c647b39b8
[ 4495.876664] Call Trace:
[ 4495.876671]  [<ffffffff868aeccc>] schedule+0x3c/0x90
[ 4495.876676]  [<ffffffff868af065>] schedule_preempt_disabled+0x15/0x20
[ 4495.876682]  [<ffffffff868b0996>] mutex_lock_nested+0x176/0x3b0
[ 4495.876686]  [<ffffffff867a2067>] ? rtnl_lock+0x17/0x20
[ 4495.876690]  [<ffffffff867a2067>] rtnl_lock+0x17/0x20
[ 4495.876720]  [<ffffffffc0ae9a5d>] brcmf_p2p_ifp_removed+0x4d/0x70 [brcmfmac]
[ 4495.876741]  [<ffffffffc0aebde6>] brcmf_remove_interface+0x196/0x1b0 [brcmfmac]
[ 4495.876760]  [<ffffffffc0ae9901>] brcmf_p2p_del_vif+0x111/0x220 [brcmfmac]
[ 4495.876777]  [<ffffffffc0adefab>] brcmf_cfg80211_del_iface+0x21b/0x270 [brcmfmac]
[ 4495.876820]  [<ffffffffc097b39e>] nl80211_del_interface+0xfe/0x3a0 [cfg80211]
[ 4495.876825]  [<ffffffff867ca335>] genl_family_rcv_msg+0x1b5/0x370
[ 4495.876832]  [<ffffffff860e5d8d>] ? trace_hardirqs_on+0xd/0x10
[ 4495.876836]  [<ffffffff867ca56d>] genl_rcv_msg+0x7d/0xb0
[ 4495.876839]  [<ffffffff867ca4f0>] ? genl_family_rcv_msg+0x370/0x370
[ 4495.876846]  [<ffffffff867c9a47>] netlink_rcv_skb+0x97/0xb0
[ 4495.876849]  [<ffffffff867ca168>] genl_rcv+0x28/0x40
[ 4495.876854]  [<ffffffff867c93c3>] netlink_unicast+0x1d3/0x2f0
[ 4495.876860]  [<ffffffff867c933b>] ? netlink_unicast+0x14b/0x2f0
[ 4495.876866]  [<ffffffff867c97cb>] netlink_sendmsg+0x2eb/0x3a0
[ 4495.876870]  [<ffffffff8676dad8>] sock_sendmsg+0x38/0x50
[ 4495.876874]  [<ffffffff8676e4df>] ___sys_sendmsg+0x27f/0x290
[ 4495.876882]  [<ffffffff8628b935>] ? mntput_no_expire+0x5/0x3f0
[ 4495.876888]  [<ffffffff8628b9be>] ? mntput_no_expire+0x8e/0x3f0
[ 4495.876894]  [<ffffffff8628b935>] ? mntput_no_expire+0x5/0x3f0
[ 4495.876899]  [<ffffffff8628bd44>] ? mntput+0x24/0x40
[ 4495.876904]  [<ffffffff86267830>] ? __fput+0x190/0x200
[ 4495.876909]  [<ffffffff8676f125>] __sys_sendmsg+0x45/0x80
[ 4495.876914]  [<ffffffff8676f172>] SyS_sendmsg+0x12/0x20
[ 4495.876918]  [<ffffffff868b5680>] entry_SYSCALL_64_fastpath+0x23/0xc1
[ 4495.876924]  [<ffffffff860e2b8f>] ? trace_hardirqs_off_caller+0x1f/0xc0
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/broadcom/brcm80211/brcmfmac/core.c

@@ -743,7 +743,7 @@ static void brcmf_del_if(struct brcmf_pub *drvr, s32 bsscfgidx,
 		 * serious troublesome side effects. The p2p module will clean
 		 * up the ifp if needed.
 		 */
-		brcmf_p2p_ifp_removed(ifp);
+		brcmf_p2p_ifp_removed(ifp, rtnl_locked);
 		kfree(ifp);
 	}
 }

drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.c

@@ -2297,7 +2297,7 @@ int brcmf_p2p_del_vif(struct wiphy *wiphy, struct wireless_dev *wdev)
 	return err;
 }
 
-void brcmf_p2p_ifp_removed(struct brcmf_if *ifp)
+void brcmf_p2p_ifp_removed(struct brcmf_if *ifp, bool rtnl_locked)
 {
 	struct brcmf_cfg80211_info *cfg;
 	struct brcmf_cfg80211_vif *vif;
@@ -2306,8 +2306,10 @@ void brcmf_p2p_ifp_removed(struct brcmf_if *ifp)
 	vif = ifp->vif;
 	cfg = wdev_to_cfg(&vif->wdev);
 	cfg->p2p.bss_idx[P2PAPI_BSSCFG_DEVICE].vif = NULL;
+	if (!rtnl_locked)
 		rtnl_lock();
 	cfg80211_unregister_wdev(&vif->wdev);
+	if (!rtnl_locked)
 		rtnl_unlock();
 	brcmf_free_vif(vif);
 }

drivers/net/wireless/broadcom/brcm80211/brcmfmac/p2p.h

@@ -155,7 +155,7 @@ struct wireless_dev *brcmf_p2p_add_vif(struct wiphy *wiphy, const char *name,
 int brcmf_p2p_del_vif(struct wiphy *wiphy, struct wireless_dev *wdev);
 int brcmf_p2p_ifchange(struct brcmf_cfg80211_info *cfg,
 		       enum brcmf_fil_p2p_if_types if_type);
-void brcmf_p2p_ifp_removed(struct brcmf_if *ifp);
+void brcmf_p2p_ifp_removed(struct brcmf_if *ifp, bool rtnl_locked);
 int brcmf_p2p_start_device(struct wiphy *wiphy, struct wireless_dev *wdev);
 void brcmf_p2p_stop_device(struct wiphy *wiphy, struct wireless_dev *wdev);
 int brcmf_p2p_scan_prep(struct wiphy *wiphy,