mt76: refactor cc_lock locking scheme
Read busy counters not holding cc_lock spinlock since usb read can't be
performed in interrupt context. Move cc_active and cc_rx counters out of
cc_lock since they are not modified in interrupt context.
Grab cc_lock updating cur_cc_bss_rx in mt76_airtime_report and do not
hold rx_lock in mt76_update_survey.
Moreover grab mt76 mutex in mt76_get_survey before running
mt76_update_survey. This patch fixes the following 'schedule while
atomic'
[ 291.790866] BUG: scheduling while atomic: iw/2161/0x00000202
[ 291.791002] Preemption disabled at:
[ 291.791007] [<
0000000000000000>] 0x0
[ 291.791015] CPU: 0 PID: 2161 Comm: iw Tainted: G W 5.4.= 0-rc2-3-ARCH-00104-g9e208aa06c21 #1
[ 291.791017] Hardware name: LENOVO 2349QM6/2349QM6, BIOS G1ETC2WW (2.82=) 08/07/2019
[ 291.791019] Call Trace:
[ 291.791042] dump_stack+0x5c/0x80
[ 291.791049] __schedule_bug.cold+0x8e/0x9b
[ 291.791055] __schedule+0x5f8/0x770
[ 291.791062] schedule+0x43/0xd0
[ 291.791068] schedule_preempt_disabled+0x14/0x20
[ 291.791074] __mutex_lock.isra.0+0x18a/0x530
[ 291.791099] mt76u_rr+0x1f/0x40 [mt76_usb]
[ 291.791113] mt76x02_update_channel+0x22/0x40 [mt76x02_lib]
[ 291.791122] mt76_update_survey+0x42/0xe0 [mt76]
[ 291.791129] mt76_get_survey+0x2f/0x1b0 [mt76]
[ 291.791170] ieee80211_dump_survey+0x5e/0x140 [mac80211]
[ 291.791217] nl80211_dump_survey+0x13c/0x2f0 [cfg80211]
[ 291.791222] ? __kmalloc_reserve.isra.0+0x2d/0x70
[ 291.791225] ? __alloc_skb+0x96/0x1d0
[ 291.791229] netlink_dump+0x17b/0x370
[ 291.791247] __netlink_dump_start+0x16f/0x1e0
[ 291.791253] genl_family_rcv_msg+0x396/0x410
[ 291.791290] ? nl80211_prepare_wdev_dump+0x1b0/0x1b0 [cfg80211]
[ 291.791297] ? _raw_spin_unlock_irqrestore+0x20/0x40
[ 291.791312] ? __wake_up_common_lock+0x8a/0xc0
[ 291.791316] genl_rcv_msg+0x47/0x90
[ 291.791320] ? genl_family_rcv_msg+0x410/0x410
[ 291.791323] netlink_rcv_skb+0x49/0x110
[ 291.791329] genl_rcv+0x24/0x40
[ 291.791333] netlink_unicast+0x171/0x200
[ 291.791340] netlink_sendmsg+0x208/0x3d0
[ 291.791358] sock_sendmsg+0x5e/0x60
[ 291.791361] ___sys_sendmsg+0x2ae/0x330
[ 291.791368] ? filemap_map_pages+0x272/0x390
[ 291.791374] ? _raw_spin_unlock+0x16/0x30
[ 291.791379] ? __handle_mm_fault+0x112f/0x1390
[ 291.791388] __sys_sendmsg+0x59/0xa0
[ 291.791396] do_syscall_64+0x5b/0x1a0
[ 291.791400] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 291.791404] RIP: 0033:0x7f5d0c7f37b7
[ 291.791418] Code: 64 89 02 48 c7 c0 ff ff ff ff eb bb 0f 1f 80 00 00 0=
0 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 2e 00 00 00 0f 05=
<48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 89 54 24 1c 48 89 74 24 10
[ 291.791421] RSP: 002b:
00007ffe8b5d0538 EFLAGS:
00000246 ORIG_RAX: 0000=
00000000002e
[ 291.791426] RAX:
ffffffffffffffda RBX:
000055a038e6c390 RCX:
00007f5d0= c7f37b7
[ 291.791430] RDX:
0000000000000000 RSI:
00007ffe8b5d0570 RDI:
000000000= 0000003
[ 291.791434] RBP:
000055a038e718c0 R08:
000055a038e6c02a R09:
000000000= 0000002
[ 291.791438] R10:
000055a03808cb00 R11:
0000000000000246 R12:
000055a03= 8e71780
[ 291.791440] R13:
00007ffe8b5d0570 R14:
000055a038e717d0 R15:
000055a03= 8e718c0
[ 291.791480] NOHZ: local_softirq_pending 202
Fixes:
168aea24f4bb ("mt76: mt76x02u: enable survey support")
Tested-by: Markus Theil <markus.theil@tu-ilmenau.de>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Felix Fietkau <nbd@nbd.name>