Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758922Ab2FQS0R (ORCPT ); Sun, 17 Jun 2012 14:26:17 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:50390 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757969Ab2FQSXC (ORCPT ); Sun, 17 Jun 2012 14:23:02 -0400 Message-Id: <20120617175945.172863157@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Sun, 17 Jun 2012 19:00:08 +0100 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Stanislaw Gruszka , Helmut Schaa , Gertjan van Wingerde , "John W. Linville" Subject: [ 27/69] rt2x00: use atomic variable for seqno In-Reply-To: <20120617175941.281333656@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:21c:bfff:fe03:f805 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7469 Lines: 179 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Stanislaw Gruszka commit e5851dac2c95af7159716832300b9f50c62c648e upstream. Remove spinlock as atomic_t can be used instead. Note we use only 16 lower bits, upper bits are changed but we impilcilty cast to u16. This fix possible deadlock on IBSS mode reproted by lockdep: ================================= [ INFO: inconsistent lock state ] 3.4.0-wl+ #4 Not tainted --------------------------------- inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage. kworker/u:2/30374 [HC0[0]:SC0[0]:HE1:SE1] takes: (&(&intf->seqlock)->rlock){+.?...}, at: [] rt2x00queue_create_tx_descriptor+0x380/0x490 [rt2x00lib] {IN-SOFTIRQ-W} state was registered at: [] __lock_acquire+0x47b/0x1050 [] lock_acquire+0x84/0xf0 [] _raw_spin_lock+0x33/0x40 [] rt2x00queue_create_tx_descriptor+0x380/0x490 [rt2x00lib] [] rt2x00queue_write_tx_frame+0x1a/0x300 [rt2x00lib] [] rt2x00mac_tx+0x7f/0x380 [rt2x00lib] [] __ieee80211_tx+0x1b3/0x300 [mac80211] [] ieee80211_tx+0x105/0x130 [mac80211] [] ieee80211_xmit+0xad/0x100 [mac80211] [] ieee80211_subif_start_xmit+0x2d9/0x930 [mac80211] [] dev_hard_start_xmit+0x307/0x660 [] sch_direct_xmit+0xa1/0x1e0 [] dev_queue_xmit+0x183/0x730 [] neigh_resolve_output+0xfa/0x1e0 [] ip_finish_output+0x24a/0x460 [] ip_output+0xb7/0x100 [] ip_local_out+0x20/0x60 [] igmpv3_sendpack+0x4f/0x60 [] igmp_ifc_timer_expire+0x29f/0x330 [] run_timer_softirq+0x15c/0x2f0 [] __do_softirq+0xae/0x1e0 irq event stamp: 18380437 hardirqs last enabled at (18380437): [] __slab_alloc.clone.3+0x67/0x5f0 hardirqs last disabled at (18380436): [] __slab_alloc.clone.3+0x33/0x5f0 softirqs last enabled at (18377616): [] __do_softirq+0x123/0x1e0 softirqs last disabled at (18377611): [] do_softirq+0x9d/0xe0 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&(&intf->seqlock)->rlock); lock(&(&intf->seqlock)->rlock); *** DEADLOCK *** 4 locks held by kworker/u:2/30374: #0: (wiphy_name(local->hw.wiphy)){++++.+}, at: [] process_one_work+0x109/0x3f0 #1: ((&sdata->work)){+.+.+.}, at: [] process_one_work+0x109/0x3f0 #2: (&ifibss->mtx){+.+.+.}, at: [] ieee80211_ibss_work+0x1b/0x470 [mac80211] #3: (&intf->beacon_skb_mutex){+.+...}, at: [] rt2x00queue_update_beacon+0x24/0x50 [rt2x00lib] stack backtrace: Pid: 30374, comm: kworker/u:2 Not tainted 3.4.0-wl+ #4 Call Trace: [] print_usage_bug+0x1f6/0x220 [] mark_lock+0x2c2/0x300 [] ? check_usage_forwards+0xc0/0xc0 [] __lock_acquire+0x4bc/0x1050 [] ? __kmalloc_track_caller+0x1c0/0x1d0 [] ? copy_skb_header+0x26/0x90 [] lock_acquire+0x84/0xf0 [] ? rt2x00queue_create_tx_descriptor+0x380/0x490 [rt2x00lib] [] _raw_spin_lock+0x33/0x40 [] ? rt2x00queue_create_tx_descriptor+0x380/0x490 [rt2x00lib] [] rt2x00queue_create_tx_descriptor+0x380/0x490 [rt2x00lib] [] rt2x00queue_update_beacon_locked+0x5f/0xb0 [rt2x00lib] [] rt2x00queue_update_beacon+0x2d/0x50 [rt2x00lib] [] rt2x00mac_bss_info_changed+0x1ca/0x200 [rt2x00lib] [] ? rt2x00mac_remove_interface+0x70/0x70 [rt2x00lib] [] ieee80211_bss_info_change_notify+0xe0/0x1d0 [mac80211] [] __ieee80211_sta_join_ibss+0x3b8/0x610 [mac80211] [] ? mark_held_locks+0x64/0xc0 [] ? virt_efi_query_capsule_caps+0x12/0x50 [] ieee80211_sta_join_ibss+0xf9/0x140 [mac80211] [] ieee80211_ibss_work+0x416/0x470 [mac80211] [] ? trace_hardirqs_on+0xb/0x10 [] ? skb_dequeue+0x4b/0x70 [] ieee80211_iface_work+0x13f/0x230 [mac80211] [] ? process_one_work+0x109/0x3f0 [] process_one_work+0x185/0x3f0 [] ? process_one_work+0x109/0x3f0 [] ? ieee80211_teardown_sdata+0xa0/0xa0 [mac80211] [] worker_thread+0x116/0x270 [] ? manage_workers+0x1e0/0x1e0 [] kthread+0x84/0x90 [] ? __init_kthread_worker+0x60/0x60 [] kernel_thread_helper+0x6/0x10 Signed-off-by: Stanislaw Gruszka Acked-by: Helmut Schaa Acked-by: Gertjan van Wingerde Signed-off-by: John W. Linville Signed-off-by: Ben Hutchings --- drivers/net/wireless/rt2x00/rt2x00.h | 3 +-- drivers/net/wireless/rt2x00/rt2x00mac.c | 1 - drivers/net/wireless/rt2x00/rt2x00queue.c | 13 ++++++------- 3 files changed, 7 insertions(+), 10 deletions(-) diff --git a/drivers/net/wireless/rt2x00/rt2x00.h b/drivers/net/wireless/rt2x00/rt2x00.h index ca36ccc..8f75402 100644 --- a/drivers/net/wireless/rt2x00/rt2x00.h +++ b/drivers/net/wireless/rt2x00/rt2x00.h @@ -396,8 +396,7 @@ struct rt2x00_intf { * for hardware which doesn't support hardware * sequence counting. */ - spinlock_t seqlock; - u16 seqno; + atomic_t seqno; }; static inline struct rt2x00_intf* vif_to_intf(struct ieee80211_vif *vif) diff --git a/drivers/net/wireless/rt2x00/rt2x00mac.c b/drivers/net/wireless/rt2x00/rt2x00mac.c index b49773e..dd24b26 100644 --- a/drivers/net/wireless/rt2x00/rt2x00mac.c +++ b/drivers/net/wireless/rt2x00/rt2x00mac.c @@ -277,7 +277,6 @@ int rt2x00mac_add_interface(struct ieee80211_hw *hw, else rt2x00dev->intf_sta_count++; - spin_lock_init(&intf->seqlock); mutex_init(&intf->beacon_skb_mutex); intf->beacon = entry; diff --git a/drivers/net/wireless/rt2x00/rt2x00queue.c b/drivers/net/wireless/rt2x00/rt2x00queue.c index 4c662ec..2fd8301 100644 --- a/drivers/net/wireless/rt2x00/rt2x00queue.c +++ b/drivers/net/wireless/rt2x00/rt2x00queue.c @@ -207,6 +207,7 @@ static void rt2x00queue_create_tx_descriptor_seq(struct rt2x00_dev *rt2x00dev, struct ieee80211_tx_info *tx_info = IEEE80211_SKB_CB(skb); struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; struct rt2x00_intf *intf = vif_to_intf(tx_info->control.vif); + u16 seqno; if (!(tx_info->flags & IEEE80211_TX_CTL_ASSIGN_SEQ)) return; @@ -238,15 +239,13 @@ static void rt2x00queue_create_tx_descriptor_seq(struct rt2x00_dev *rt2x00dev, * sequence counting per-frame, since those will override the * sequence counter given by mac80211. */ - spin_lock(&intf->seqlock); - if (test_bit(ENTRY_TXD_FIRST_FRAGMENT, &txdesc->flags)) - intf->seqno += 0x10; - hdr->seq_ctrl &= cpu_to_le16(IEEE80211_SCTL_FRAG); - hdr->seq_ctrl |= cpu_to_le16(intf->seqno); - - spin_unlock(&intf->seqlock); + seqno = atomic_add_return(0x10, &intf->seqno); + else + seqno = atomic_read(&intf->seqno); + hdr->seq_ctrl &= cpu_to_le16(IEEE80211_SCTL_FRAG); + hdr->seq_ctrl |= cpu_to_le16(seqno); } static void rt2x00queue_create_tx_descriptor_plcp(struct rt2x00_dev *rt2x00dev, -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/