From 1c4abec0baf25ffb92a28cc99d4231feeaa4d3f3 Mon Sep 17 00:00:00 2001 From: Emmanuel Grumbach Date: Thu, 8 May 2014 09:48:10 +0300 Subject: [PATCH] iwlwifi: mvm: fix setting channel in monitor mode There was a deadlock in monitor mode when we were setting the channel if the channel was not 1. ====================================================== [ INFO: possible circular locking dependency detected ] 3.14.3 #4 Not tainted ------------------------------------------------------- iw/3323 is trying to acquire lock: (&local->chanctx_mtx){+.+.+.}, at: [] ieee80211_vif_release_channel+0x42/0xb0 [mac80211] but task is already holding lock: (&local->iflist_mtx){+.+...}, at: [] ieee80211_set_monitor_channel+0x5a/0x1b0 [mac80211] which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&local->iflist_mtx){+.+...}: [] __lock_acquire+0xb3b/0x13b0 [] lock_acquire+0xb0/0x1f0 [] mutex_lock_nested+0x78/0x4f0 [] ieee80211_iterate_active_interfaces+0x2f/0x60 [mac80211] [] iwl_mvm_recalc_multicast+0x49/0xa0 [iwlmvm] [] iwl_mvm_configure_filter+0x4e/0x70 [iwlmvm] [] ieee80211_configure_filter+0x153/0x5f0 [mac80211] [] ieee80211_reconfig_filter+0x15/0x20 [mac80211] [snip] -> #1 (&mvm->mutex){+.+.+.}: [] __lock_acquire+0xb3b/0x13b0 [] lock_acquire+0xb0/0x1f0 [] mutex_lock_nested+0x78/0x4f0 [] iwl_mvm_add_chanctx+0x56/0xe0 [iwlmvm] [] ieee80211_new_chanctx+0x13e/0x410 [mac80211] [] ieee80211_vif_use_channel+0x1c3/0x5a0 [mac80211] [] ieee80211_add_virtual_monitor+0x1ab/0x6b0 [mac80211] [] ieee80211_do_open+0xe6a/0x15a0 [mac80211] [] ieee80211_open+0x59/0x60 [mac80211] [snip] -> #0 (&local->chanctx_mtx){+.+.+.}: [] check_prevs_add+0x977/0x980 [] __lock_acquire+0xb3b/0x13b0 [] lock_acquire+0xb0/0x1f0 [] mutex_lock_nested+0x78/0x4f0 [] ieee80211_vif_release_channel+0x42/0xb0 [mac80211] [] ieee80211_set_monitor_channel+0x113/0x1b0 [mac80211] [] cfg80211_set_monitor_channel+0x77/0x2b0 [cfg80211] [] __nl80211_set_channel+0x122/0x140 [cfg80211] [] nl80211_set_wiphy+0x284/0xaf0 [cfg80211] [snip] other info that might help us debug this: Chain exists of: &local->chanctx_mtx --> &mvm->mutex --> &local->iflist_mtx Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&local->iflist_mtx); lock(&mvm->mutex); lock(&local->iflist_mtx); lock(&local->chanctx_mtx); *** DEADLOCK *** This deadlock actually occurs: INFO: task iw:3323 blocked for more than 120 seconds. Not tainted 3.14.3 #4 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. iw D ffff8800c8afcd80 4192 3323 3322 0x00000000 ffff880078fdb7e0 0000000000000046 ffff8800c8afcd80 ffff880078fdbfd8 00000000001d5540 00000000001d5540 ffff8801141b0000 ffff8800c8afcd80 ffff880078ff9e38 ffff880078ff9e38 ffff880078ff9e40 0000000000000246 Call Trace: [] schedule_preempt_disabled+0x31/0x80 [] mutex_lock_nested+0x19d/0x4f0 [] ? ieee80211_iterate_active_interfaces+0x2f/0x60 [mac80211] [] ? ieee80211_iterate_active_interfaces+0x2f/0x60 [mac80211] [] ? iwl_mvm_power_mac_update_mode+0xc0/0xc0 [iwlmvm] [] ieee80211_iterate_active_interfaces+0x2f/0x60 [mac80211] [] _iwl_mvm_power_update_binding+0x27/0x80 [iwlmvm] [] iwl_mvm_unassign_vif_chanctx+0x81/0xc0 [iwlmvm] [] __ieee80211_vif_release_channel+0xdf/0x470 [mac80211] [] ieee80211_vif_release_channel+0x4a/0xb0 [mac80211] [] ieee80211_set_monitor_channel+0x113/0x1b0 [mac80211] [] cfg80211_set_monitor_channel+0x77/0x2b0 [cfg80211] [] __nl80211_set_channel+0x122/0x140 [cfg80211] [] nl80211_set_wiphy+0x284/0xaf0 [cfg80211] This fixes https://bugzilla.kernel.org/show_bug.cgi?id=75541 Cc: [3.13+] Reviewed-by: Johannes Berg Signed-off-by: Emmanuel Grumbach --- drivers/net/wireless/iwlwifi/mvm/mac80211.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/wireless/iwlwifi/mvm/mac80211.c b/drivers/net/wireless/iwlwifi/mvm/mac80211.c index 593f723a74c4..4b0b8b6571ee 100644 --- a/drivers/net/wireless/iwlwifi/mvm/mac80211.c +++ b/drivers/net/wireless/iwlwifi/mvm/mac80211.c @@ -1007,7 +1007,7 @@ static void iwl_mvm_mc_iface_iterator(void *_data, u8 *mac, memcpy(cmd->bssid, vif->bss_conf.bssid, ETH_ALEN); len = roundup(sizeof(*cmd) + cmd->count * ETH_ALEN, 4); - ret = iwl_mvm_send_cmd_pdu(mvm, MCAST_FILTER_CMD, CMD_SYNC, len, cmd); + ret = iwl_mvm_send_cmd_pdu(mvm, MCAST_FILTER_CMD, CMD_ASYNC, len, cmd); if (ret) IWL_ERR(mvm, "mcast filter cmd error. ret=%d\n", ret); } @@ -1023,7 +1023,7 @@ static void iwl_mvm_recalc_multicast(struct iwl_mvm *mvm) if (WARN_ON_ONCE(!mvm->mcast_filter_cmd)) return; - ieee80211_iterate_active_interfaces( + ieee80211_iterate_active_interfaces_atomic( mvm->hw, IEEE80211_IFACE_ITER_NORMAL, iwl_mvm_mc_iface_iterator, &iter_data); }