staging: rtl8723bs: remove a third possible deadlock
The assoc_timer takes the pmlmepriv->lock and various functions which take the pmlmepriv->scanned_queue.lock first take the pmlmepriv->lock, this means that we cannot have code which waits for the timer (timer_del_sync) while holding the pmlmepriv->scanned_queue.lock to avoid a triangle deadlock: [ 363.139361] ====================================================== [ 363.139377] WARNING: possible circular locking dependency detected [ 363.139396] 5.15.0-rc1+ #470 Tainted: G C E [ 363.139413] ------------------------------------------------------ [ 363.139424] RTW_CMD_THREAD/2466 is trying to acquire lock: [ 363.139441] ffffbacd00699038 (&pmlmepriv->lock){+.-.}-{2:2}, at: _rtw_join_timeout_handler+0x3c/0x160 [r8723bs] [ 363.139598] but task is already holding lock: [ 363.139610] ffffbacd00128ea0 ((&pmlmepriv->assoc_timer)){+.-.}-{0:0}, at: call_timer_fn+0x5/0x260 [ 363.139673] which lock already depends on the new lock. [ 363.139684] the existing dependency chain (in reverse order) is: [ 363.139696] -> #2 ((&pmlmepriv->assoc_timer)){+.-.}-{0:0}: [ 363.139734] del_timer_sync+0x59/0x100 [ 363.139762] rtw_joinbss_event_prehandle+0x342/0x640 [r8723bs] [ 363.139870] report_join_res+0xdf/0x110 [r8723bs] [ 363.139980] OnAssocRsp+0x17a/0x200 [r8723bs] [ 363.140092] rtw_recv_entry+0x190/0x1120 [r8723bs] [ 363.140209] rtl8723b_process_phy_info+0x3f9/0x750 [r8723bs] [ 363.140318] tasklet_action_common.constprop.0+0xe8/0x110 [ 363.140345] __do_softirq+0xde/0x485 [ 363.140372] __irq_exit_rcu+0xd0/0x100 [ 363.140393] irq_exit_rcu+0xa/0x20 [ 363.140413] common_interrupt+0x83/0xa0 [ 363.140440] asm_common_interrupt+0x1e/0x40 [ 363.140463] finish_task_switch.isra.0+0x157/0x3d0 [ 363.140492] __schedule+0x447/0x1880 [ 363.140516] schedule+0x59/0xc0 [ 363.140537] smpboot_thread_fn+0x161/0x1c0 [ 363.140565] kthread+0x143/0x160 [ 363.140585] ret_from_fork+0x22/0x30 [ 363.140614] -> #1 (&pmlmepriv->scanned_queue.lock){+.-.}-{2:2}: [ 363.140653] _raw_spin_lock_bh+0x34/0x40 [ 363.140675] rtw_free_network_queue+0x31/0x80 [r8723bs] [ 363.140776] rtw_sitesurvey_cmd+0x79/0x1e0 [r8723bs] [ 363.140869] rtw_cfg80211_surveydone_event_callback+0x3cf/0x470 [r8723bs] [ 363.140973] rdev_scan+0x42/0x1a0 [cfg80211] [ 363.141307] nl80211_trigger_scan+0x566/0x660 [cfg80211] [ 363.141635] genl_family_rcv_msg_doit+0xcd/0x110 [ 363.141661] genl_rcv_msg+0xce/0x1c0 [ 363.141680] netlink_rcv_skb+0x50/0xf0 [ 363.141699] genl_rcv+0x24/0x40 [ 363.141717] netlink_unicast+0x16d/0x230 [ 363.141736] netlink_sendmsg+0x22b/0x450 [ 363.141755] sock_sendmsg+0x5e/0x60 [ 363.141781] ____sys_sendmsg+0x22f/0x270 [ 363.141803] ___sys_sendmsg+0x81/0xc0 [ 363.141828] __sys_sendmsg+0x49/0x80 [ 363.141851] do_syscall_64+0x3b/0x90 [ 363.141873] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 363.141895] -> #0 (&pmlmepriv->lock){+.-.}-{2:2}: [ 363.141930] __lock_acquire+0x1158/0x1de0 [ 363.141954] lock_acquire+0xb5/0x2b0 [ 363.141974] _raw_spin_lock_bh+0x34/0x40 [ 363.141993] _rtw_join_timeout_handler+0x3c/0x160 [r8723bs] [ 363.142097] call_timer_fn+0x94/0x260 [ 363.142122] __run_timers.part.0+0x1bf/0x290 [ 363.142147] run_timer_softirq+0x26/0x50 [ 363.142171] __do_softirq+0xde/0x485 [ 363.142193] __irq_exit_rcu+0xd0/0x100 [ 363.142215] irq_exit_rcu+0xa/0x20 [ 363.142235] sysvec_apic_timer_interrupt+0x72/0x90 [ 363.142260] asm_sysvec_apic_timer_interrupt+0x12/0x20 [ 363.142283] __module_address.part.0+0x0/0xd0 [ 363.142309] is_module_address+0x25/0x40 [ 363.142334] static_obj+0x4f/0x60 [ 363.142361] lockdep_init_map_type+0x47/0x220 [ 363.142382] __init_swait_queue_head+0x45/0x60 [ 363.142408] mmc_wait_for_req+0x4a/0xc0 [mmc_core] [ 363.142504] mmc_wait_for_cmd+0x55/0x70 [mmc_core] [ 363.142592] mmc_io_rw_direct+0x75/0xe0 [mmc_core] [ 363.142691] sdio_writeb+0x2e/0x50 [mmc_core] [ 363.142788] _sd_cmd52_write+0x62/0x80 [r8723bs] [ 363.142885] sd_cmd52_write+0x6c/0xb0 [r8723bs] [ 363.142981] rtl8723bs_set_hal_ops+0x982/0x9b0 [r8723bs] [ 363.143089] rtw_write16+0x1e/0x30 [r8723bs] [ 363.143184] SetHwReg8723B+0xcc9/0xd30 [r8723bs] [ 363.143294] mlmeext_joinbss_event_callback+0x17a/0x1a0 [r8723bs] [ 363.143405] rtw_joinbss_event_callback+0x11/0x20 [r8723bs] [ 363.143507] mlme_evt_hdl+0x4d/0x70 [r8723bs] [ 363.143620] rtw_cmd_thread+0x168/0x3c0 [r8723bs] [ 363.143712] kthread+0x143/0x160 [ 363.143732] ret_from_fork+0x22/0x30 [ 363.143757] other info that might help us debug this: [ 363.143768] Chain exists of: &pmlmepriv->lock --> &pmlmepriv->scanned_queue.lock --> (&pmlmepriv->assoc_timer) [ 363.143809] Possible unsafe locking scenario: [ 363.143819] CPU0 CPU1 [ 363.143831] ---- ---- [ 363.143841] lock((&pmlmepriv->assoc_timer)); [ 363.143862] lock(&pmlmepriv->scanned_queue.lock); [ 363.143882] lock((&pmlmepriv->assoc_timer)); [ 363.143902] lock(&pmlmepriv->lock); [ 363.143921] *** DEADLOCK *** Make rtw_joinbss_event_prehandle() release the scanned_queue.lock before it deletes the timer to avoid this (it is still holding pmlmepriv->lock protecting against racing the timer). Signed-off-by: Hans de Goede <hdegoede@redhat.com> Link: https://lore.kernel.org/r/20210920145502.155454-3-hdegoede@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Hans de Goede
Greg Kroah-Hartman
parent
a7ac783c33
commit
bdc1bbdbaa
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@ -1236,16 +1236,13 @@ void rtw_joinbss_event_prehandle(struct adapter *adapter, u8 *pbuf)
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rtw_indicate_connect(adapter);
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}
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spin_unlock_bh(&pmlmepriv->scanned_queue.lock);
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/* s5. Cancel assoc_timer */
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del_timer_sync(&pmlmepriv->assoc_timer);
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} else {
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spin_unlock_bh(&(pmlmepriv->scanned_queue.lock));
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goto ignore_joinbss_callback;
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}
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spin_unlock_bh(&(pmlmepriv->scanned_queue.lock));
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} else if (pnetwork->join_res == -4) {
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rtw_reset_securitypriv(adapter);
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_set_timer(&pmlmepriv->assoc_timer, 1);
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