From 7dd6753f6d2e7e0ccbf2263cef3a9fff6bc89988 Mon Sep 17 00:00:00 2001 From: Bob Copeland Date: Sun, 12 Aug 2012 21:18:33 -0400 Subject: ath5k: fix spin_lock_irqsave/spin_lock_bh nesting in mesh Lockdep found an inconsistent lock state when joining a mesh with ath5k. The problem is that ath5k takes the lock for its beacon state, ah->block, with spin_lock_irqsave(), while mesh internally takes the sync_offset_lock with spin_lock_bh() in mesh_sync_offset_adjust_tbtt(), which in turn is called under ah->block. This could deadlock if the beacon tasklet was run on the processor that held the beacon lock during the do_softirq() in spin_unlock_bh(). We probably shouldn't hold the lock around the callbacks, but the easiest fix is to switch to spin_lock_bh for ah->block: it doesn't need interrupts disabled anyway as the data in question is only accessed in softirq or process context. Fixes the following lockdep warning: [ 446.892304] WARNING: at kernel/softirq.c:159 _local_bh_enable_ip+0x38/0xa6() [ 446.892306] Hardware name: MacBook1,1 [ 446.892309] Modules linked in: tcp_lp fuse sunrpc cpufreq_ondemand acpi_cpufreq mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 nf_conntrack_ipv4 ip6table_filter nf_defrag_ipv4 xt_state nf_conntrack ip6_tables ext2 arc4 btusb bluetooth snd_hda_codec_idt snd_hda_intel carl9170 snd_hda_codec coretemp joydev ath5k snd_hwdep snd_seq isight_firmware ath snd_seq_device snd_pcm applesmc appletouch mac80211 input_polldev snd_timer microcode cfg80211 snd lpc_ich pcspkr i2c_i801 mfd_core soundcore rfkill snd_page_alloc sky2 tpm_infineon virtio_net kvm_intel kvm i915 drm_kms_helper drm i2c_algo_bit i2c_core video [ 446.892385] Pid: 1892, comm: iw Not tainted 3.6.0-rc1-wl+ #296 [ 446.892387] Call Trace: [ 446.892394] [] warn_slowpath_common+0x7c/0x91 [ 446.892398] [] ? _local_bh_enable_ip+0x38/0xa6 [ 446.892403] [] ? _local_bh_enable_ip+0x38/0xa6 [ 446.892459] [] ? mesh_sync_offset_adjust_tbtt+0x95/0x99 [mac80211] [ 446.892464] [] warn_slowpath_null+0x22/0x24 [ 446.892468] [] _local_bh_enable_ip+0x38/0xa6 [ 446.892473] [] local_bh_enable_ip+0xd/0xf [ 446.892479] [] _raw_spin_unlock_bh+0x34/0x37 [ 446.892527] [] mesh_sync_offset_adjust_tbtt+0x95/0x99 [mac80211] [ 446.892569] [] ieee80211_beacon_get_tim+0x28f/0x4e0 [mac80211] [ 446.892575] [] ? trace_hardirqs_on_caller+0x10e/0x13f [ 446.892591] [] ath5k_beacon_update+0x40/0x26b [ath5k] [ 446.892597] [] ? lock_acquired+0x1f5/0x21e [ 446.892612] [] ? ath5k_bss_info_changed+0x167/0x1b2 [ath5k] [ 446.892617] [] ? _raw_spin_lock_irqsave+0x78/0x82 [ 446.892632] [] ? ath5k_bss_info_changed+0x167/0x1b2 [ath5k] [ 446.892647] [] ath5k_bss_info_changed+0x175/0x1b2 [ath5k] [ 446.892651] [] ? lock_is_held+0x73/0x7b [ 446.892662] [] ? __might_sleep+0xa7/0x17a [ 446.892698] [] ieee80211_bss_info_change_notify+0x1ed/0x21a [mac80211] [ 446.892703] [] ? queue_work+0x24/0x32 [ 446.892718] [] ? ath5k_configure_filter+0x163/0x163 [ath5k] [ 446.892766] [] ieee80211_start_mesh+0xb9/0xbd [mac80211] [ 446.892806] [] ieee80211_join_mesh+0x10c/0x116 [mac80211] [ 446.892834] [] __cfg80211_join_mesh+0x176/0x1b3 [cfg80211] [ 446.892855] [] cfg80211_join_mesh+0x4f/0x6a [cfg80211] [ 446.892875] [] nl80211_join_mesh+0x1de/0x1ed [cfg80211] [ 446.892908] [] ? nl80211_set_wiphy+0x4cf/0x4cf [cfg80211] [ 446.892919] [] genl_rcv_msg+0x1d5/0x1f3 [ 446.892940] [] ? genl_rcv+0x25/0x25 [ 446.892946] [] netlink_rcv_skb+0x37/0x78 [ 446.892950] [] genl_rcv+0x1e/0x25 [ 446.892955] [] netlink_unicast+0xc3/0x12d [ 446.892959] [] netlink_sendmsg+0x1e9/0x213 [ 446.892966] [] sock_sendmsg+0x79/0x96 [ 446.892972] [] ? might_fault+0x9d/0xa3 [ 446.892978] [] ? copy_from_user+0x8/0xa [ 446.892983] [] ? verify_iovec+0x43/0x77 [ 446.892987] [] __sys_sendmsg+0x180/0x215 [ 446.892993] [] ? sched_clock_cpu+0x134/0x144 [ 446.892997] [] ? trace_hardirqs_off+0xb/0xd [ 446.893002] [] ? __lock_acquire+0x46b/0xb6e [ 446.893006] [] ? trace_hardirqs_off+0xb/0xd [ 446.893010] [] ? local_clock+0x32/0x49 [ 446.893015] [] ? lock_release_holdtime.part.9+0x4b/0x51 [ 446.893020] [] ? lock_is_held+0x73/0x7b [ 446.893025] [] ? fcheck_files+0x97/0xcd [ 446.893029] [] ? fget_light+0x2d/0x81 [ 446.893034] [] sys_sendmsg+0x3b/0x52 [ 446.893038] [] sys_socketcall+0x238/0x2a2 [ 446.893044] [] sysenter_do_call+0x12/0x38 [ 446.893047] ---[ end trace a9af5998f929270f ]--- [ 447.627222] [ 447.627232] ================================= [ 447.627237] [ INFO: inconsistent lock state ] [ 447.627244] 3.6.0-rc1-wl+ #296 Tainted: G W [ 447.627248] --------------------------------- [ 447.627253] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. [ 447.627260] swapper/0/0 [HC0[0]:SC1[1]:HE1:SE0] takes: [ 447.627264] (&(&ah->block)->rlock){+.?...}, at: [] ath5k_tasklet_beacon+0x91/0xa7 [ath5k] [ 447.627299] {SOFTIRQ-ON-W} state was registered at: [ 447.627304] [] mark_held_locks+0x59/0x77 [ 447.627316] [] trace_hardirqs_on_caller+0x10e/0x13f [ 447.627324] [] trace_hardirqs_on+0xb/0xd [ 447.627332] [] _local_bh_enable_ip+0x9e/0xa6 [ 447.627342] [] local_bh_enable_ip+0xd/0xf [ 447.627349] [] _raw_spin_unlock_bh+0x34/0x37 [ 447.627359] [] mesh_sync_offset_adjust_tbtt+0x95/0x99 [mac80211] [ 447.627451] [] ieee80211_beacon_get_tim+0x28f/0x4e0 [mac80211] [ 447.627526] [] ath5k_beacon_update+0x40/0x26b [ath5k] [ 447.627547] [] ath5k_bss_info_changed+0x175/0x1b2 [ath5k] [ 447.627569] [] ieee80211_bss_info_change_notify+0x1ed/0x21a [mac80211] [ 447.627628] [] ieee80211_start_mesh+0xb9/0xbd [mac80211] [ 447.627712] [] ieee80211_join_mesh+0x10c/0x116 [mac80211] [ 447.627782] [] __cfg80211_join_mesh+0x176/0x1b3 [cfg80211] [ 447.627816] [] cfg80211_join_mesh+0x4f/0x6a [cfg80211] [ 447.627845] [] nl80211_join_mesh+0x1de/0x1ed [cfg80211] [ 447.627872] [] genl_rcv_msg+0x1d5/0x1f3 [ 447.627881] [] netlink_rcv_skb+0x37/0x78 [ 447.627891] [] genl_rcv+0x1e/0x25 [ 447.627898] [] netlink_unicast+0xc3/0x12d [ 447.627907] [] netlink_sendmsg+0x1e9/0x213 [ 447.627915] [] sock_sendmsg+0x79/0x96 [ 447.627926] [] __sys_sendmsg+0x180/0x215 [ 447.627934] [] sys_sendmsg+0x3b/0x52 [ 447.627941] [] sys_socketcall+0x238/0x2a2 [ 447.627949] [] sysenter_do_call+0x12/0x38 [ 447.627959] irq event stamp: 1929200 [ 447.627963] hardirqs last enabled at (1929200): [] tasklet_hi_action+0x3e/0xbf [ 447.627972] hardirqs last disabled at (1929199): [] tasklet_hi_action+0x15/0xbf [ 447.627981] softirqs last enabled at (1929196): [] _local_bh_enable+0x12/0x14 [ 447.627989] softirqs last disabled at (1929197): [] do_softirq+0x63/0xb8 [ 447.627999] [ 447.627999] other info that might help us debug this: [ 447.628004] Possible unsafe locking scenario: [ 447.628004] [ 447.628009] CPU0 [ 447.628012] ---- [ 447.628016] lock(&(&ah->block)->rlock); [ 447.628023] [ 447.628027] lock(&(&ah->block)->rlock); [ 447.628034] [ 447.628034] *** DEADLOCK *** Signed-off-by: Bob Copeland Signed-off-by: John W. Linville --- drivers/net/wireless/ath/ath5k/mac80211-ops.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'drivers/net/wireless/ath/ath5k/mac80211-ops.c') diff --git a/drivers/net/wireless/ath/ath5k/mac80211-ops.c b/drivers/net/wireless/ath/ath5k/mac80211-ops.c index 260e7dc7f751..d56453e43d7e 100644 --- a/drivers/net/wireless/ath/ath5k/mac80211-ops.c +++ b/drivers/net/wireless/ath/ath5k/mac80211-ops.c @@ -254,7 +254,6 @@ ath5k_bss_info_changed(struct ieee80211_hw *hw, struct ieee80211_vif *vif, struct ath5k_vif *avf = (void *)vif->drv_priv; struct ath5k_hw *ah = hw->priv; struct ath_common *common = ath5k_hw_common(ah); - unsigned long flags; mutex_lock(&ah->lock); @@ -300,9 +299,9 @@ ath5k_bss_info_changed(struct ieee80211_hw *hw, struct ieee80211_vif *vif, } if (changes & BSS_CHANGED_BEACON) { - spin_lock_irqsave(&ah->block, flags); + spin_lock_bh(&ah->block); ath5k_beacon_update(hw, vif); - spin_unlock_irqrestore(&ah->block, flags); + spin_unlock_bh(&ah->block); } if (changes & BSS_CHANGED_BEACON_ENABLED) -- cgit v1.2.3-59-g8ed1b