[1/3] usb: host: xhci: fix oops when removing hcd

[Peter Chen <peter.chen@nxp.com>]

The USB3 HCD structure (xhci->shared_hcd) may be NULL when the USB3
interrupt occurs, the typical use case is we plug out Type-C-to-A cable,
and there is a USB device at the port. The platform controller driver
(eg, dwc3) unregisters xhci platform driver, and remove hcd accordingly.
It is very easy to reproduce if there is a USB3 HUB on the port, and there
is no USB3 device on HUB's port, the controller is at U3, it performs
a far-end receiver termination detection every 100 ms, so the USB3 port
change interrupt may be occurs 100ms maximum later when we plug out
Type-C-to-A cable, and the USB3 HCD has already been NULL at that time.
The oops log like below:

[681.782288] xhci-hcd xhci-hcd.1.auto: remove, state 1
[681.787490] usb usb4: USB disconnect, device number 1
[681.792808] usb 4-1: USB disconnect, device number 2
[681.818089] xhci-hcd xhci-hcd.1.auto: USB bus 4 deregistered
[681.823803] Unable to handle kernel NULL pointer dereference at virtual address 000000a0
[681.823806] Mem abort info:
[681.823809]   Exception class = DABT (current EL), IL = 32 bits
[681.823811]   SET = 0, FnV = 0
[681.823813]   EA = 0, S1PTW = 0
[681.823814] Data abort info:
[681.823816]   ISV = 0, ISS = 0x00000004
[681.823818]   CM = 0, WnR = 0
[681.823822] user pgtable: 4k pages, 48-bit VAs, pgd = ffff8000ae3fd000
[681.823824] [00000000000000a0] *pgd=0000000000000000
[681.823829] Internal error: Oops: 96000004 [#1] PREEMPT SMP
[681.823832] Modules linked in: 8021q garp stp mrp crc32_ce qca6174(O) crct10dif_ce galcore(O)
[681.823849] CPU: 0 PID: 94 Comm: kworker/0:1 Tainted: G           O    4.14.62-imx_4.14.y+gcd63def #1
[681.823851] Hardware name: Freescale i.MX8MQ EVK (DT)
[681.823862] Workqueue: events_freezable __dwc3_set_mode
[681.823865] task: ffff8000b8a18000 task.stack: ffff00000a010000
[681.823872] PC is at xhci_irq+0x5fc/0x14b8
[681.823875] LR is at xhci_irq+0x3c/0x14b8
[681.823878] pc : [<ffff0000088ff204>] lr : [<ffff0000088fec44>] pstate: 800001c5
[681.823880] sp : ffff000008003b20
[681.823882] x29: ffff000008003b20 x28: ffff00000a53df10
[681.823886] x27: ffff8000ae3c0238 x26: 00000000000001c0
[681.823890] x25: ffff8000ae3c0000 x24: ffff00000a53df10
[681.823893] x23: 0000000000000000 x22: ffff000009297db8
[681.823897] x21: ffff000008f3f0e8 x20: 0000000000000001
[681.823901] x19: ffff8000ae3c0284 x18: 0000000000000010
[681.823904] x17: 0000000000427268 x16: 00000000000000f1
[681.823908] x15: ffffffffffffffff x14: 0000000000000000
[681.823911] x13: ffff000008db0500 x12: 0000000000000001
[681.823915] x11: ffff000008db0508 x10: 0000000000000040
[681.823918] x9 : ffff0000094e4088 x8 : ffff8000b6020000
[681.823922] x7 : ffff8000b6020028 x6 : 0000000000000001
[681.823925] x5 : 0000000000000001 x4 : 0000000000000000
[681.823928] x3 : 0000000000000003 x2 : 0000000000000002
[681.823932] x1 : ffff8000ae3c0000 x0 : ffff8000b48b8c00
[681.823936] Process kworker/0:1 (pid: 94, stack limit = 0xffff00000a010000)
[681.823938] Call trace:
[681.823942] Exception stack(0xffff0000080039e0 to 0xffff000008003b20)
[681.823946] 39e0: ffff8000b48b8c00 ffff8000ae3c0000 0000000000000002 0000000000000003
[681.823950] 3a00: 0000000000000000 0000000000000001 0000000000000001 ffff8000b6020028
[681.823953] 3a20: ffff8000b6020000 ffff0000094e4088 0000000000000040 ffff000008db0508
[681.823957] 3a40: 0000000000000001 ffff000008db0500 0000000000000000 ffffffffffffffff
[681.823960] 3a60: 00000000000000f1 0000000000427268 0000000000000010 ffff8000ae3c0284
[681.823964] 3a80: 0000000000000001 ffff000008f3f0e8 ffff000009297db8 0000000000000000
[681.823968] 3aa0: ffff00000a53df10 ffff8000ae3c0000 00000000000001c0 ffff8000ae3c0238
[681.823972] 3ac0: ffff00000a53df10 ffff000008003b20 ffff0000088fec44 ffff000008003b20
[681.823975] 3ae0: ffff0000088ff204 00000000800001c5 ffff7e0002d0bb40 ffff8000b42ed880
[681.823979] 3b00: 0000ffffffffffff ffff0000081fd2b4 ffff000008003b20 ffff0000088ff204
[681.823984] [<ffff0000088ff204>] xhci_irq+0x5fc/0x14b8
[681.823991] [<ffff00000889d3a4>] usb_hcd_irq+0x2c/0x48
[681.823997] [<ffff000008123ecc>] __handle_irq_event_percpu+0x5c/0x148
[681.824000] [<ffff000008123fd4>] handle_irq_event_percpu+0x1c/0x58
[681.824003] [<ffff000008124058>] handle_irq_event+0x48/0x78
[681.824008] [<ffff000008127e30>] handle_fasteoi_irq+0xa8/0x180
[681.824014] [<ffff000008122fec>] generic_handle_irq+0x24/0x38
[681.824018] [<ffff00000812366c>] __handle_domain_irq+0x5c/0xb8
[681.824023] [<ffff000008081960>] gic_handle_irq+0x78/0x17c
[681.824026] Exception stack(0xffff000008003d90 to 0xffff000008003ed0)
[681.824029] 3d80:                                   0000000000000000 ffff000009667700
[681.824032] 3da0: 0000000000000708 0000000000000000 0000000000000016 00ffffffffffffff
[681.824036] 3dc0: 00000000363b4285 7fffffffffffffff ffff8000bdf62db8 0000000000000004
[681.824039] 3de0: 00000000000000f1 ffff000008db0508 0000000000000001 ffff000008db0500
[681.824043] 3e00: 0000000000000000 ffffffffffffffff 00000000000000f1 0000000000427268
[681.824047] 3e20: 0000000000000010 ffff8000b8a18000 0000000000000003 ffff000009667700
[681.824051] 3e40: ffff0000094b0018 ffff8000b8006c00 ffff000009664000 00000001000174c1
[681.824055] 3e60: ffff000008004000 ffff000008daf000 0000000000000202 ffff000008003ed0
[681.824058] 3e80: ffff000008081ad4 ffff000008003ed0 ffff000008081b14 0000000040000145
[681.824062] 3ea0: ffff8000b8a18000 0000000000000003 0000ffffffffffff 0000000000000003
[681.824065] 3ec0: ffff000008003ed0 ffff000008081b14
[681.824068] [<ffff000008083230>] el1_irq+0xb0/0x124
[681.824072] [<ffff000008081b14>] __do_softirq+0xac/0x228
[681.824078] [<ffff0000080d4aac>] irq_exit+0xc4/0x100
[681.824083] [<ffff000008123670>] __handle_domain_irq+0x60/0xb8
[681.824086] [<ffff000008081960>] gic_handle_irq+0x78/0x17c
[681.824089] Exception stack(0xffff00000a013770 to 0xffff00000a0138b0)
[681.824091] 3760:                                   0000000000000020 ffff8000b8a18000
[681.824095] 3780: 00008000b4aa6000 ffffffffffffffff 0000000000000000 0000000000000000
[681.824099] 37a0: 000000000000000f 2034207375622042 7473696765726564 0000000000000006
[681.824102] 37c0: ffff00000a013820 ffff000008633128 ffff0000094c9df8 ffff00000966d45d
[681.824106] 37e0: ffff00008966d44f ffffffffffffffff 0000ffff9bf1f358 0000000000427268
[681.824109] 3800: 0000000000000010 0000000000000000 0000000000000140 ffff00000966c000
[681.824113] 3820: ffff00000966cef8 ffff0000094c9000 ffff00000966dcc8 ffff0000094b0018
[681.824117] 3840: 0000000000000040 0000000000000000 ffff00000966cec8 ffff00000a0138b0
[681.824120] 3860: ffff000008121194 ffff00000a0138b0 ffff000008121198 0000000040000145
[681.824124] 3880: ffff00000966c000 ffff00000966cef8 ffffffffffffffff ffff00000966dcc8
[681.824127] 38a0: ffff00000a0138b0 ffff000008121198
[681.824130] [<ffff000008083230>] el1_irq+0xb0/0x124
[681.824134] [<ffff000008121198>] console_unlock.part.8+0x208/0x418
[681.824138] [<ffff000008121628>] vprintk_emit+0x250/0x2e0
[681.824144] [<ffff0000086d3fac>] dev_vprintk_emit+0x104/0x220
[681.824148] [<ffff0000086d4110>] dev_printk_emit+0x48/0x50
[681.824152] [<ffff0000086d41a4>] __dev_printk+0x3c/0x78
[681.824155] [<ffff0000086d44cc>] _dev_info+0x4c/0x58
[681.824159] [<ffff00000889e53c>] usb_deregister_bus+0x34/0x70
[681.824162] [<ffff00000889f578>] usb_remove_hcd+0x130/0x1d8
[681.824165] [<ffff000008903640>] xhci_plat_remove+0x48/0xe0
[681.824170] [<ffff0000086da70c>] platform_drv_remove+0x24/0x50
[681.824175] [<ffff0000086d8e44>] device_release_driver_internal+0x174/0x208
[681.824180] [<ffff0000086d8eec>] device_release_driver+0x14/0x20
[681.824184] [<ffff0000086d7c8c>] bus_remove_device+0x114/0x128
[681.824188] [<ffff0000086d480c>] device_del+0x1ac/0x300
[681.824192] [<ffff0000086dad1c>] platform_device_del.part.3+0x24/0x90
[681.824196] [<ffff0000086dadc0>] platform_device_unregister+0x18/0x38
[681.824200] [<ffff0000088b8b8c>] dwc3_host_exit+0x54/0x68
[681.824204] [<ffff0000088b6e5c>] __dwc3_set_mode+0x1f4/0x210
[681.824210] [<ffff0000080e8aec>] process_one_work+0x1d4/0x348
[681.824213] [<ffff0000080e8ca8>] worker_thread+0x48/0x470
[681.824218] [<ffff0000080eefac>] kthread+0x12c/0x130
[681.824223] [<ffff000008084ed8>] ret_from_fork+0x10/0x18
[681.824227] Code: f9400777 34002183 7103fc7f 54003680 (b940a2e4)
[681.824236] ---[ end trace 3ecbb9c7f9dc3d7f ]---
[681.824239] Kernel panic - not syncing: Fatal exception in interrupt
[681.824243] SMP: stopping secondary CPUs
[681.824298] Kernel Offset: disabled
[681.824301] CPU features: 0x080200c
[681.824303] Memory Limit: none
[682.518113] ---[ end Kernel panic - not syncing: Fatal exception in interrupt

Signed-off-by: Peter Chen <peter.chen@nxp.com>
---
 drivers/usb/host/xhci-ring.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index f0a99aa0ac58..2dc5176b79d0 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -2680,7 +2680,8 @@ irqreturn_t xhci_irq(struct usb_hcd *hcd)
 	}
 
 	if (xhci->xhc_state & XHCI_STATE_DYING ||
-	    xhci->xhc_state & XHCI_STATE_HALTED) {
+	    xhci->xhc_state & XHCI_STATE_HALTED ||
+	    xhci->xhc_state & XHCI_STATE_REMOVING) {
 		xhci_dbg(xhci, "xHCI dying, ignoring interrupt. "
 				"Shouldn't IRQs be disabled?\n");
 		/* Clear the event handler busy flag (RW1C);