From: Lorenzo Bianconi lorenzo@kernel.org
[ Upstream commit 5f0ce5848733b86deaba1c6d102e20479230b20a ]
Fix the following possible deadlock reported by lockdep disabling BH running mt76_free_pending_txwi()
================================ WARNING: inconsistent lock state 5.9.0-rc6 #14 Not tainted -------------------------------- inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage. rmmod/1227 [HC0[0]:SC0[0]:HE1:SE1] takes: ffff888156a83530 (&dev->lock#2){+.?.}-{2:2}, at: mt76_dma_cleanup+0x125/0x150 [mt76] {IN-SOFTIRQ-W} state was registered at: __lock_acquire+0x20c/0x6b0 lock_acquire+0x9d/0x220 _raw_spin_lock+0x2c/0x70 mt76_dma_tx_cleanup+0xc7/0x200 [mt76] mt76x02_poll_tx+0x31/0xb0 [mt76x02_lib] napi_poll+0x3a/0x100 net_rx_action+0xa8/0x200 __do_softirq+0xc4/0x430 asm_call_on_stack+0xf/0x20 do_softirq_own_stack+0x49/0x60 irq_exit_rcu+0x9a/0xd0 common_interrupt+0xa4/0x190 asm_common_interrupt+0x1e/0x40 irq event stamp: 9915 hardirqs last enabled at (9915): [<ffffffff8124e286>] __free_pages_ok+0x336/0x3b0 hardirqs last disabled at (9914): [<ffffffff8124e24e>] __free_pages_ok+0x2fe/0x3b0 softirqs last enabled at (9912): [<ffffffffa03aa672>] mt76_dma_rx_cleanup+0xa2/0x120 [mt76] softirqs last disabled at (9846): [<ffffffffa03aa5ea>] mt76_dma_rx_cleanup+0x1a/0x120 [mt76]
other info that might help us debug this: Possible unsafe locking scenario:
CPU0 ---- lock(&dev->lock#2); <Interrupt> lock(&dev->lock#2);
*** DEADLOCK ***
1 lock held by rmmod/1227: #0: ffff88815b5eb240 (&dev->mutex){....}-{3:3}, at: driver_detach+0xb5/0x110
stack backtrace: CPU: 1 PID: 1227 Comm: rmmod Kdump: loaded Not tainted 5.9.0-rc6-wdn-src+ #14 Hardware name: Dell Inc. Studio XPS 1340/0K183D, BIOS A11 09/08/2009 Call Trace: dump_stack+0x77/0xa0 mark_lock_irq.cold+0x15/0x39 mark_lock+0x1fc/0x500 mark_usage+0xc7/0x140 __lock_acquire+0x20c/0x6b0 ? find_held_lock+0x2b/0x80 ? sched_clock_cpu+0xc/0xb0 lock_acquire+0x9d/0x220 ? mt76_dma_cleanup+0x125/0x150 [mt76] _raw_spin_lock+0x2c/0x70 ? mt76_dma_cleanup+0x125/0x150 [mt76] mt76_dma_cleanup+0x125/0x150 [mt76] mt76x2_cleanup+0x5a/0x70 [mt76x2e] mt76x2e_remove+0x18/0x30 [mt76x2e] pci_device_remove+0x36/0xa0 __device_release_driver+0x16c/0x220 driver_detach+0xcf/0x110 bus_remove_driver+0x56/0xca pci_unregister_driver+0x36/0x80 __do_sys_delete_module.constprop.0+0x127/0x200 ? syscall_enter_from_user_mode+0x1d/0x50 ? trace_hardirqs_on+0x1c/0xe0 do_syscall_64+0x33/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7ff0da54e36b Code: 73 01 c3 48 8b 0d 2d 0b 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 b0 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d fd 0a 0c 00 f7 d8 64 89 01 48
Fixes: dd57a95cfddc ("mt76: move txwi handling code to dma.c, since it is mmio specific") Signed-off-by: Lorenzo Bianconi lorenzo@kernel.org Signed-off-by: Felix Fietkau nbd@nbd.name Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/wireless/mediatek/mt76/dma.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/net/wireless/mediatek/mt76/dma.c b/drivers/net/wireless/mediatek/mt76/dma.c index 214fc95b8a33f..145e839fea4e5 100644 --- a/drivers/net/wireless/mediatek/mt76/dma.c +++ b/drivers/net/wireless/mediatek/mt76/dma.c @@ -72,9 +72,11 @@ mt76_free_pending_txwi(struct mt76_dev *dev) { struct mt76_txwi_cache *t;
+ local_bh_disable(); while ((t = __mt76_get_txwi(dev)) != NULL) dma_unmap_single(dev->dev, t->dma_addr, dev->drv->txwi_size, DMA_TO_DEVICE); + local_bh_enable(); }
static int