Commit e5851dac authored by Stanislaw Gruszka's avatar Stanislaw Gruszka Committed by John W. Linville

rt2x00: use atomic variable for seqno

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: [<f9979a20>] rt2x00queue_create_tx_descriptor+0x380/0x490 [rt2x00lib]
{IN-SOFTIRQ-W} state was registered at:
  [<c04978ab>] __lock_acquire+0x47b/0x1050
  [<c0498504>] lock_acquire+0x84/0xf0
  [<c0835733>] _raw_spin_lock+0x33/0x40
  [<f9979a20>] rt2x00queue_create_tx_descriptor+0x380/0x490 [rt2x00lib]
  [<f9979f2a>] rt2x00queue_write_tx_frame+0x1a/0x300 [rt2x00lib]
  [<f997834f>] rt2x00mac_tx+0x7f/0x380 [rt2x00lib]
  [<f98fe363>] __ieee80211_tx+0x1b3/0x300 [mac80211]
  [<f98ffdf5>] ieee80211_tx+0x105/0x130 [mac80211]
  [<f99000dd>] ieee80211_xmit+0xad/0x100 [mac80211]
  [<f9900519>] ieee80211_subif_start_xmit+0x2d9/0x930 [mac80211]
  [<c0782e87>] dev_hard_start_xmit+0x307/0x660
  [<c079bb71>] sch_direct_xmit+0xa1/0x1e0
  [<c0784bb3>] dev_queue_xmit+0x183/0x730
  [<c078c27a>] neigh_resolve_output+0xfa/0x1e0
  [<c07b436a>] ip_finish_output+0x24a/0x460
  [<c07b4897>] ip_output+0xb7/0x100
  [<c07b2d60>] ip_local_out+0x20/0x60
  [<c07e01ff>] igmpv3_sendpack+0x4f/0x60
  [<c07e108f>] igmp_ifc_timer_expire+0x29f/0x330
  [<c04520fc>] run_timer_softirq+0x15c/0x2f0
  [<c0449e3e>] __do_softirq+0xae/0x1e0
irq event stamp: 18380437
hardirqs last  enabled at (18380437): [<c0526027>] __slab_alloc.clone.3+0x67/0x5f0
hardirqs last disabled at (18380436): [<c0525ff3>] __slab_alloc.clone.3+0x33/0x5f0
softirqs last  enabled at (18377616): [<c0449eb3>] __do_softirq+0x123/0x1e0
softirqs last disabled at (18377611): [<c041278d>] do_softirq+0x9d/0xe0

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&(&intf->seqlock)->rlock);
  <Interrupt>
    lock(&(&intf->seqlock)->rlock);

 *** DEADLOCK ***

4 locks held by kworker/u:2/30374:
 #0:  (wiphy_name(local->hw.wiphy)){++++.+}, at: [<c045cf99>] process_one_work+0x109/0x3f0
 #1:  ((&sdata->work)){+.+.+.}, at: [<c045cf99>] process_one_work+0x109/0x3f0
 #2:  (&ifibss->mtx){+.+.+.}, at: [<f98f005b>] ieee80211_ibss_work+0x1b/0x470 [mac80211]
 #3:  (&intf->beacon_skb_mutex){+.+...}, at: [<f997a644>] rt2x00queue_update_beacon+0x24/0x50 [rt2x00lib]

stack backtrace:
Pid: 30374, comm: kworker/u:2 Not tainted 3.4.0-wl+ #4
Call Trace:
 [<c04962a6>] print_usage_bug+0x1f6/0x220
 [<c0496a12>] mark_lock+0x2c2/0x300
 [<c0495ff0>] ? check_usage_forwards+0xc0/0xc0
 [<c04978ec>] __lock_acquire+0x4bc/0x1050
 [<c0527890>] ? __kmalloc_track_caller+0x1c0/0x1d0
 [<c0777fb6>] ? copy_skb_header+0x26/0x90
 [<c0498504>] lock_acquire+0x84/0xf0
 [<f9979a20>] ? rt2x00queue_create_tx_descriptor+0x380/0x490 [rt2x00lib]
 [<c0835733>] _raw_spin_lock+0x33/0x40
 [<f9979a20>] ? rt2x00queue_create_tx_descriptor+0x380/0x490 [rt2x00lib]
 [<f9979a20>] rt2x00queue_create_tx_descriptor+0x380/0x490 [rt2x00lib]
 [<f997a5cf>] rt2x00queue_update_beacon_locked+0x5f/0xb0 [rt2x00lib]
 [<f997a64d>] rt2x00queue_update_beacon+0x2d/0x50 [rt2x00lib]
 [<f9977e3a>] rt2x00mac_bss_info_changed+0x1ca/0x200 [rt2x00lib]
 [<f9977c70>] ? rt2x00mac_remove_interface+0x70/0x70 [rt2x00lib]
 [<f98e4dd0>] ieee80211_bss_info_change_notify+0xe0/0x1d0 [mac80211]
 [<f98ef7b8>] __ieee80211_sta_join_ibss+0x3b8/0x610 [mac80211]
 [<c0496ab4>] ? mark_held_locks+0x64/0xc0
 [<c0440012>] ? virt_efi_query_capsule_caps+0x12/0x50
 [<f98efb09>] ieee80211_sta_join_ibss+0xf9/0x140 [mac80211]
 [<f98f0456>] ieee80211_ibss_work+0x416/0x470 [mac80211]
 [<c0496d8b>] ? trace_hardirqs_on+0xb/0x10
 [<c077683b>] ? skb_dequeue+0x4b/0x70
 [<f98f207f>] ieee80211_iface_work+0x13f/0x230 [mac80211]
 [<c045cf99>] ? process_one_work+0x109/0x3f0
 [<c045d015>] process_one_work+0x185/0x3f0
 [<c045cf99>] ? process_one_work+0x109/0x3f0
 [<f98f1f40>] ? ieee80211_teardown_sdata+0xa0/0xa0 [mac80211]
 [<c045ed86>] worker_thread+0x116/0x270
 [<c045ec70>] ? manage_workers+0x1e0/0x1e0
 [<c0462f64>] kthread+0x84/0x90
 [<c0462ee0>] ? __init_kthread_worker+0x60/0x60
 [<c083d382>] kernel_thread_helper+0x6/0x10

Cc: stable@vger.kernel.org
Signed-off-by: default avatarStanislaw Gruszka <sgruszka@redhat.com>
Acked-by: default avatarHelmut Schaa <helmut.schaa@googlemail.com>
Acked-by: default avatarGertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent f304a993
...@@ -396,8 +396,7 @@ struct rt2x00_intf { ...@@ -396,8 +396,7 @@ struct rt2x00_intf {
* for hardware which doesn't support hardware * for hardware which doesn't support hardware
* sequence counting. * sequence counting.
*/ */
spinlock_t seqlock; atomic_t seqno;
u16 seqno;
}; };
static inline struct rt2x00_intf* vif_to_intf(struct ieee80211_vif *vif) static inline struct rt2x00_intf* vif_to_intf(struct ieee80211_vif *vif)
......
...@@ -277,7 +277,6 @@ int rt2x00mac_add_interface(struct ieee80211_hw *hw, ...@@ -277,7 +277,6 @@ int rt2x00mac_add_interface(struct ieee80211_hw *hw,
else else
rt2x00dev->intf_sta_count++; rt2x00dev->intf_sta_count++;
spin_lock_init(&intf->seqlock);
mutex_init(&intf->beacon_skb_mutex); mutex_init(&intf->beacon_skb_mutex);
intf->beacon = entry; intf->beacon = entry;
......
...@@ -207,6 +207,7 @@ static void rt2x00queue_create_tx_descriptor_seq(struct rt2x00_dev *rt2x00dev, ...@@ -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_tx_info *tx_info = IEEE80211_SKB_CB(skb);
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data; struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
struct rt2x00_intf *intf = vif_to_intf(tx_info->control.vif); struct rt2x00_intf *intf = vif_to_intf(tx_info->control.vif);
u16 seqno;
if (!(tx_info->flags & IEEE80211_TX_CTL_ASSIGN_SEQ)) if (!(tx_info->flags & IEEE80211_TX_CTL_ASSIGN_SEQ))
return; return;
...@@ -238,15 +239,13 @@ static void rt2x00queue_create_tx_descriptor_seq(struct rt2x00_dev *rt2x00dev, ...@@ -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 counting per-frame, since those will override the
* sequence counter given by mac80211. * sequence counter given by mac80211.
*/ */
spin_lock(&intf->seqlock);
if (test_bit(ENTRY_TXD_FIRST_FRAGMENT, &txdesc->flags)) if (test_bit(ENTRY_TXD_FIRST_FRAGMENT, &txdesc->flags))
intf->seqno += 0x10; seqno = atomic_add_return(0x10, &intf->seqno);
hdr->seq_ctrl &= cpu_to_le16(IEEE80211_SCTL_FRAG); else
hdr->seq_ctrl |= cpu_to_le16(intf->seqno); seqno = atomic_read(&intf->seqno);
spin_unlock(&intf->seqlock);
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, static void rt2x00queue_create_tx_descriptor_plcp(struct rt2x00_dev *rt2x00dev,
......
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