This is a note to let you know that I've just added the patch titled
rt2x00: use atomic variable for seqno
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
rt2x00-use-atomic-variable-for-seqno.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From e5851dac2c95af7159716832300b9f50c62c648e Mon Sep 17 00:00:00 2001
From: Stanislaw Gruszka <[email protected]>
Date: Fri, 1 Jun 2012 11:29:40 +0200
Subject: rt2x00: use atomic variable for seqno
From: Stanislaw Gruszka <[email protected]>
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: [<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
Signed-off-by: Stanislaw Gruszka <[email protected]>
Acked-by: Helmut Schaa <[email protected]>
Acked-by: Gertjan van Wingerde <[email protected]>
Signed-off-by: John W. Linville <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
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(-)
--- 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)
--- a/drivers/net/wireless/rt2x00/rt2x00mac.c
+++ b/drivers/net/wireless/rt2x00/rt2x00mac.c
@@ -277,7 +277,6 @@ int rt2x00mac_add_interface(struct ieee8
else
rt2x00dev->intf_sta_count++;
- spin_lock_init(&intf->seqlock);
mutex_init(&intf->beacon_skb_mutex);
intf->beacon = entry;
--- a/drivers/net/wireless/rt2x00/rt2x00queue.c
+++ b/drivers/net/wireless/rt2x00/rt2x00queue.c
@@ -207,6 +207,7 @@ static void rt2x00queue_create_tx_descri
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;
@@ -227,15 +228,13 @@ static void rt2x00queue_create_tx_descri
* 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,
Patches currently in stable-queue which might be from [email protected] are
queue-3.4/rt2x00-use-atomic-variable-for-seqno.patch
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