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: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Helmut Schaa <helmut.schaa@googlemail.com>
Acked-by: Gertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
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 @@
* 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 b49773ef..dd24b26 100644
--- a/drivers/net/wireless/rt2x00/rt2x00mac.c
+++ b/drivers/net/wireless/rt2x00/rt2x00mac.c
@@ -277,7 +277,6 @@
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 @@
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 @@
* 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;
+ 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(intf->seqno);
-
- spin_unlock(&intf->seqlock);
-
+ hdr->seq_ctrl |= cpu_to_le16(seqno);
}
static void rt2x00queue_create_tx_descriptor_plcp(struct rt2x00_dev *rt2x00dev,
