On Sat, 2019-04-27 at 22:41 +0200, Erik Stromdahl wrote: > This patch fixes a possible deadlock when updating the TX statistics > (when calling into ieee80211_tx_stats()) from ieee80211_tx_dequeue(). > > ieee80211_tx_dequeue() might be called from process context. I think this really is the problem. > [<c0cb1864>] (ieee80211_xmit_fast_finish) from [<c0cb4504>] (ieee80211_tx_dequeue+0x30c/0xb9c) > r10:d2f1a900 r9:d2d607a4 r8:d2cf20dc r7:d330b29c r6:d2cf2000 r5:d2c342ba > r4:d2899d3c > [<c0cb41f8>] (ieee80211_tx_dequeue) from [<bf057f64>] (ath10k_mac_tx_push_txq+0x78/0x2a4 [ath10k_core]) > r10:d2d607cc r9:d2fe06a0 r8:00000000 r7:d2fe1e30 r6:d2fe1d38 r5:d2fe1540 > r4:d2cf20dc > [<bf057eec>] (ath10k_mac_tx_push_txq [ath10k_core]) from [<bf058364>] (ath10k_mac_tx_push_pending+0x1d4/0x2e0 [ath10k_core]) > r10:d2cf20dc r9:bf0582b4 r8:bf0b1dba r7:00000002 r6:c1429994 r5:00000000 > r4:d2fe06a0 > [<bf058190>] (ath10k_mac_tx_push_pending [ath10k_core]) from [<bf0e25a4>] (ath10k_sdio_irq_handler+0x30c/0x4d8 [ath10k_sdio]) > r10:00005b5a r9:d2fcc040 r8:00180201 r7:d2fe6540 r6:d2fe6a7c r5:00000000 > r4:d2fe1540 It seems to be entirely ath10k's fault, and quite possibly our documentation, but we probably should have local_bh_disable() there rather than try to do u64_stats_update_begin_irqsave() in some path that really doesn't need it. This is going to be whack-a-mole otherwise - the TX path in mac80211 really expects to not be interrupted by softirqs. johannes
