CPU0 CPU1 --------------------------------------------------------------------- __driver_attach() device_lock(&dev->mutex) <--- device mutex lock here driver_probe_device() pci_enable_sriov() pci_iov_add_virtfn() pci_device_add() aer_isr() <--- pci aer error do_recovery() broadcast_error_message() pci_walk_bus() down_read(&pci_bus_sem) <--- rd sem down_write(&pci_bus_sem) <-- stuck on wr sem report_error_detected() device_lock(&dev->mutex)<--- DEAD LOCK This can also happen when aer error occurs while pci_dev->sriov_config() is called. This patch does a pci_bus_walk and adds all the devices to a list. After unlocking (up_read) &pci_bus_sem, we go through the list and call err_handler of the devices with devic_lock() held. This way, we dont try to hold both locks at same time. v2: * Drop patch 1, 2 & 4. * Instead of locking 50+ devices, do get_device() and add them to a list. After unlocking &pci_bus_sem, go through the list call err_handler. v1: * Previous discussion here: https://lkml.org/lkml/2017/9/27/720 [ 70.984091] pcieport 0000:00:02.0: AER: Uncorrected (Non-Fatal) error received: id=0010 [ 70.984112] pcieport 0000:00:02.0: PCIe Bus Error: severity=Uncorrected (Non-Fatal), type=Transaction Layer, id=0010(Requester ID) [ 70.984116] pcieport 0000:00:02.0: device [8086:3c04] error status/mask=00004000/00100000 [ 70.984120] pcieport 0000:00:02.0: [14] Completion Timeout (First) ... [ 107.484190] INFO: task kworker/0:1:76 blocked for more than 30 seconds. [ 107.563619] Not tainted 4.13.0+ #28 [ 107.611618] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 107.705368] kworker/0:1 D 0 76 2 0x80000000 [ 107.771050] Workqueue: events aer_isr [ 107.814895] Call Trace: [ 107.844181] __schedule+0x312/0xa40 [ 107.885928] schedule+0x3d/0x90 [ 107.923506] schedule_preempt_disabled+0x15/0x20 [ 107.978773] __mutex_lock+0x304/0xa30 [ 108.022594] ? dev_printk_emit+0x3b/0x50 [ 108.069534] ? report_error_detected+0xa6/0x210 [ 108.123770] mutex_lock_nested+0x1b/0x20 [ 108.170713] ? mutex_lock_nested+0x1b/0x20 [ 108.219730] report_error_detected+0xa6/0x210 [ 108.271881] ? aer_recover_queue+0xe0/0xe0 [ 108.320904] pci_walk_bus+0x46/0x90 [ 108.362645] ? aer_recover_queue+0xe0/0xe0 [ 108.411658] broadcast_error_message+0xc3/0xf0 [ 108.464835] do_recovery+0x34/0x220 [ 108.506569] ? get_device_error_info+0x92/0x130 [ 108.560785] aer_isr+0x28f/0x3b0 [ 108.599410] process_one_work+0x277/0x6c0 [ 108.647399] worker_thread+0x4d/0x3b0 [ 108.691218] kthread+0x171/0x190 [ 108.729830] ? process_one_work+0x6c0/0x6c0 [ 108.779888] ? kthread_create_on_node+0x40/0x40 [ 108.834110] ret_from_fork+0x2a/0x40 [ 108.876916] INFO: task kworker/0:2:205 blocked for more than 30 seconds. [ 108.957129] Not tainted 4.13.0+ #28 [ 109.005114] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 109.098873] kworker/0:2 D 0 205 2 0x80000000 [ 109.164544] Workqueue: events work_for_cpu_fn [ 109.216681] Call Trace: [ 109.245943] __schedule+0x312/0xa40 [ 109.287687] ? rwsem_down_write_failed+0x308/0x4f0 [ 109.345021] schedule+0x3d/0x90 [ 109.382603] rwsem_down_write_failed+0x30d/0x4f0 [ 109.437869] ? __lock_acquire+0x75c/0x1410 [ 109.486910] call_rwsem_down_write_failed+0x17/0x30 [ 109.545287] ? call_rwsem_down_write_failed+0x17/0x30 [ 109.605752] down_write+0x88/0xb0 [ 109.645410] pci_device_add+0x158/0x240 [ 109.691313] pci_iov_add_virtfn+0x24f/0x340 [ 109.741375] pci_enable_sriov+0x32b/0x420 [ 109.789466] ? pci_read+0x2c/0x30 [ 109.829142] enic_probe+0x5d4/0xff0 [enic] [ 109.878184] ? trace_hardirqs_on+0xd/0x10 [ 109.926180] local_pci_probe+0x42/0xa0 [ 109.971037] work_for_cpu_fn+0x14/0x20 [ 110.015898] process_one_work+0x277/0x6c0 [ 110.063884] worker_thread+0x1d6/0x3b0 [ 110.108750] kthread+0x171/0x190 [ 110.147363] ? process_one_work+0x6c0/0x6c0 [ 110.197426] ? kthread_create_on_node+0x40/0x40 [ 110.251642] ret_from_fork+0x2a/0x40 [ 110.294448] INFO: task systemd-udevd:492 blocked for more than 30 seconds. [ 110.376742] Not tainted 4.13.0+ #28 [ 110.424715] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 110.518457] systemd-udevd D 0 492 444 0x80000180 [ 110.584116] Call Trace: [ 110.613382] __schedule+0x312/0xa40 [ 110.655127] ? wait_for_completion+0x14a/0x1d0 [ 110.708302] schedule+0x3d/0x90 [ 110.745875] schedule_timeout+0x26e/0x5b0 [ 110.793887] ? wait_for_completion+0x14a/0x1d0 [ 110.847068] wait_for_completion+0x169/0x1d0 [ 110.898165] ? wait_for_completion+0x169/0x1d0 [ 110.951354] ? wake_up_q+0x80/0x80 [ 110.992060] flush_work+0x237/0x300 [ 111.033795] ? flush_workqueue_prep_pwqs+0x1b0/0x1b0 [ 111.093224] ? wait_for_completion+0x5a/0x1d0 [ 111.145363] ? flush_work+0x237/0x300 [ 111.189189] work_on_cpu+0x94/0xb0 [ 111.229894] ? work_is_static_object+0x20/0x20 [ 111.283070] ? pci_device_shutdown+0x60/0x60 [ 111.334173] pci_device_probe+0x17a/0x190 [ 111.382163] driver_probe_device+0x2ff/0x450 [ 111.433260] __driver_attach+0x103/0x140 [ 111.480195] ? driver_probe_device+0x450/0x450 [ 111.533381] bus_for_each_dev+0x74/0xb0 [ 111.579276] driver_attach+0x1e/0x20 [ 111.622056] bus_add_driver+0x1ca/0x270 [ 111.667955] ? 0xffffffffc039c000 [ 111.707616] driver_register+0x60/0xe0 [ 111.752472] ? 0xffffffffc039c000 [ 111.792126] __pci_register_driver+0x6b/0x70 [ 111.843275] enic_init_module+0x38/0x1000 [enic] [ 111.898533] do_one_initcall+0x50/0x192 [ 111.944428] ? trace_hardirqs_on+0xd/0x10 [ 111.992408] do_init_module+0x5f/0x1f2 [ 112.037274] load_module+0x1740/0x1f70 [ 112.082148] SYSC_finit_module+0xd7/0xf0 [ 112.129083] ? SYSC_finit_module+0xd7/0xf0 [ 112.178106] SyS_finit_module+0xe/0x10 [ 112.222972] do_syscall_64+0x69/0x180 [ 112.266793] entry_SYSCALL64_slow_path+0x25/0x25 [ 112.322047] RIP: 0033:0x7f3da098b559 [ 112.364826] RSP: 002b:00007ffeb3306a38 EFLAGS: 00000246 ORIG_RAX: 0000000000000139 [ 112.455447] RAX: ffffffffffffffda RBX: 0000557fe41ed3d0 RCX: 00007f3da098b559 [ 112.540860] RDX: 0000000000000000 RSI: 00007f3da14c79c5 RDI: 0000000000000006 [ 112.626281] RBP: 00007f3da14c79c5 R08: 0000000000000000 R09: 00007ffeb3306b50 [ 112.711698] R10: 0000000000000006 R11: 0000000000000246 R12: 0000000000000000 [ 112.797114] R13: 0000557fe420e210 R14: 0000000000020000 R15: 0000557fe2c1ef4a [ 112.882568] Showing all locks held in the system: [ 112.956545] 5 locks held by kworker/0:1/76: [ 113.006616] #0: ("events"){+.+.}, at: [<ffffffffb00b10ed>] process_one_work+0x1ed/0x6c0 [ 113.104535] #1: ((&rpc->dpc_handler)){+.+.}, at: [<ffffffffb00b10ed>] process_one_work+0x1ed/0x6c0 [ 113.213894] #2: (&rpc->rpc_mutex){+.+.}, at: [<ffffffffb0505ca2>] aer_isr+0x32/0x3b0 [ 113.308711] #3: (pci_bus_sem){++++}, at: [<ffffffffb04ea18a>] pci_walk_bus+0x2a/0x90 [ 113.403501] #4: (&dev->mutex){....}, at: [<ffffffffb0505706>] report_error_detected+0xa6/0x210 [ 113.508715] 3 locks held by kworker/0:2/205: [ 113.559808] #0: ("events"){+.+.}, at: [<ffffffffb00b10ed>] process_one_work+0x1ed/0x6c0 [ 113.657718] #1: ((&wfc.work)){+.+.}, at: [<ffffffffb00b10ed>] process_one_work+0x1ed/0x6c0 [ 113.758745] #2: (pci_bus_sem){++++}, at: [<ffffffffb04ec978>] pci_device_add+0x158/0x240 [ 113.857710] 1 lock held by khungtaskd/239: [ 113.906729] #0: (tasklist_lock){.+.+}, at: [<ffffffffb00f07dd>] debug_show_all_locks+0x3d/0x1a0 [ 114.012972] 2 locks held by systemd-udevd/492: [ 114.066148] #0: (&dev->mutex){....}, at: [<ffffffffb06254d5>] __driver_attach+0x55/0x140 [ 114.165107] #1: (&dev->mutex){....}, at: [<ffffffffb06254f2>] __driver_attach+0x72/0x140 [ 114.281879] ============================================= Signed-off-by: Govindarajulu Varadarajan <gvaradar@xxxxxxxxx> --- drivers/pci/pcie/aer/aerdrv.h | 5 +++++ drivers/pci/pcie/aer/aerdrv_core.c | 45 ++++++++++++++++++++++++++++++++++++-- 2 files changed, 48 insertions(+), 2 deletions(-) diff --git a/drivers/pci/pcie/aer/aerdrv.h b/drivers/pci/pcie/aer/aerdrv.h index d51e4a57b190..f6d8761dc656 100644 --- a/drivers/pci/pcie/aer/aerdrv.h +++ b/drivers/pci/pcie/aer/aerdrv.h @@ -105,6 +105,11 @@ static inline pci_ers_result_t merge_result(enum pci_ers_result orig, return orig; } +struct aer_device_list { + struct device *dev; + struct hlist_node node; +}; + extern struct bus_type pcie_port_bus_type; void aer_isr(struct work_struct *work); void aer_print_error(struct pci_dev *dev, struct aer_err_info *info); diff --git a/drivers/pci/pcie/aer/aerdrv_core.c b/drivers/pci/pcie/aer/aerdrv_core.c index 890efcc574cb..d524f2c2c288 100644 --- a/drivers/pci/pcie/aer/aerdrv_core.c +++ b/drivers/pci/pcie/aer/aerdrv_core.c @@ -346,6 +346,47 @@ static int report_resume(struct pci_dev *dev, void *data) return 0; } +int aer_get_pci_dev(struct pci_dev *pdev, void *data) +{ + struct hlist_head *hhead = (struct hlist_head *)data; + struct device *dev = &pdev->dev; + struct aer_device_list *entry; + + entry = kmalloc(sizeof(*entry), GFP_KERNEL); + if (!entry) + /* continue with other devices, lets not return error */ + return 0; + + entry->dev = get_device(dev); + hlist_add_head(&entry->node, hhead); + + return 0; +} + +static void aer_pci_walk_bus(struct pci_bus *top, + int (*cb)(struct pci_dev *, void *), + struct aer_broadcast_data *result) +{ + HLIST_HEAD(dev_hlist); + struct hlist_node *tmp; + struct aer_device_list *entry; + + pci_walk_bus(top, aer_get_pci_dev, &dev_hlist); + hlist_for_each_entry_safe(entry, tmp, &dev_hlist, node) { + struct pci_dev *pdev = container_of(entry->dev, struct pci_dev, + dev); + int err; + + err = cb(pdev, result); + if (err) + dev_err(entry->dev, "AER: recovery handler failed: %d", + err); + put_device(entry->dev); + hlist_del(&entry->node); + kfree(entry); + } +} + /** * broadcast_error_message - handle message broadcast to downstream drivers * @dev: pointer to from where in a hierarchy message is broadcasted down @@ -380,7 +421,7 @@ static pci_ers_result_t broadcast_error_message(struct pci_dev *dev, */ if (cb == report_error_detected) dev->error_state = state; - pci_walk_bus(dev->subordinate, cb, &result_data); + aer_pci_walk_bus(dev->subordinate, cb, &result_data); if (cb == report_resume) { pci_cleanup_aer_uncorrect_error_status(dev); dev->error_state = pci_channel_io_normal; @@ -390,7 +431,7 @@ static pci_ers_result_t broadcast_error_message(struct pci_dev *dev, * If the error is reported by an end point, we think this * error is related to the upstream link of the end point. */ - pci_walk_bus(dev->bus, cb, &result_data); + aer_pci_walk_bus(dev->bus, cb, &result_data); } return result_data.result; -- 2.14.1
