diff options
author | Fupan Li <fupan.li@windriver.com> | 2015-08-03 14:19:43 +0300 |
---|---|---|
committer | Felipe Balbi <balbi@ti.com> | 2015-08-03 17:49:47 +0300 |
commit | a24b071bb4ac37ef51a0ed4765f89be05a617677 (patch) | |
tree | 904855797ec0929682c838508471518e2d8bfb18 /drivers | |
parent | 2f0bb2a0e7f5161e83615fb1283c5079566ed6a7 (diff) | |
download | linux-a24b071bb4ac37ef51a0ed4765f89be05a617677.tar.xz |
usb: gadget: f_printer: fix deadlock caused by nested spinlock
Function printer_func_disable() has called spinlock on printer_dev->lock,
and it'll call function chain of
printer_reset_interface()
|
+---dwc3_gadget_ep_disable()
|
+---__dwc3_gadget_ep_disable()
|
+---dwc3_remove_requests()
|
+---dwc3_gadget_giveback()
|
+---rx_complete()
in the protected block.
However, rx_complete() in f_printer.c calls spinlock on printer_dev->lock
again, which will cause system hang.
The following steps can reproduce this hang:
1. Build the test program from Documentation/usb/gadget_printer.txt as
g_printer
2. Plug in the USB device to a host(such as Ubuntu).
3. on the USB device system run:
#modprobe g_printer.ko
#./g_printer -read_data
4. Unplug the USB device from the host
The system will hang later.
In order to avoid this deadlock, moving the spinlock from
printer_func_disable() into printer_reset_interface() and excluding the block
of calling dwc3_gadget_ep_disable(), in which the critical resource will be
protected by its spinlock in rx_complete().
This commit will fix the system hang with the following calltrace:
INFO: rcu_preempt detected stalls on CPUs/tasks: { 3} (detected by 0, t=21006 jiffies, g=524, c=523, q=2)
sending NMI to all CPUs:
NMI backtrace for cpu 3
CPU: 3 PID: 718 Comm: irq/22-dwc3 Not tainted 3.10.38-ltsi-WR6.0.0.11_standard #2
Hardware name: Intel Corp. VALLEYVIEW B3 PLATFORM/NOTEBOOK, BIOS BYTICRB1.86C.0092.R32.1410021707 10/02/2014
task: f44f4c20 ti: f40f6000 task.ti: f40f6000
EIP: 0060:[<c1824955>] EFLAGS: 00000097 CPU: 3
EIP is at _raw_spin_lock_irqsave+0x35/0x40
EAX: 00000076 EBX: f80fad00 ECX: 00000076 EDX: 00000075
ESI: 00000096 EDI: ffffff94 EBP: f40f7e20 ESP: f40f7e18
DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
CR0: 8005003b CR2: b77ac000 CR3: 01c30000 CR4: 001007f0
DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
DR6: ffff0ff0 DR7: 00000400
Stack:
f474a720 f80fad00 f40f7e3c f80f93cc c135d486 00000000 f474a720 f468fb00
f4bea894 f40f7e54 f7e35f19 ffffff00 f468fb00 f468fb24 00000086 f40f7e64
f7e36577 f468fb00 f4bea810 f40f7e74 f7e365a8 f468fb00 f4bea894 f40f7e9c
Call Trace:
[<f80f93cc>] rx_complete+0x1c/0xb0 [g_printer]
[<c135d486>] ? vsnprintf+0x166/0x390
[<f7e35f19>] dwc3_gadget_giveback+0xc9/0xf0 [dwc3]
[<f7e36577>] dwc3_remove_requests+0x57/0x70 [dwc3]
[<f7e365a8>] __dwc3_gadget_ep_disable+0x18/0x60 [dwc3]
[<f7e366e9>] dwc3_gadget_ep_disable+0x89/0xf0 [dwc3]
[<f80f9031>] printer_reset_interface+0x31/0x50 [g_printer]
[<f80f9270>] printer_func_disable+0x20/0x30 [g_printer]
[<f80e6d8b>] composite_disconnect+0x4b/0x90 [libcomposite]
[<f7e39a8b>] dwc3_disconnect_gadget+0x38/0x43 [dwc3]
[<f7e39ad4>] dwc3_gadget_disconnect_interrupt+0x3e/0x5a [dwc3]
[<f7e373b8>] dwc3_thread_interrupt+0x5c8/0x610 [dwc3]
[<c10ac518>] irq_thread_fn+0x18/0x30
[<c10ac800>] irq_thread+0x100/0x130
[<c10ac500>] ? irq_finalize_oneshot.part.29+0xb0/0xb0
[<c10ac650>] ? wake_threads_waitq+0x40/0x40
[<c10ac700>] ? irq_thread_dtor+0xb0/0xb0
[<c1057224>] kthread+0x94/0xa0
[<c182b337>] ret_from_kernel_thread+0x1b/0x28
[<c1057190>] ? kthread_create_on_node+0xc0/0xc0
Signed-off-by: Fupan Li <fupan.li@windriver.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/usb/gadget/function/f_printer.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/usb/gadget/function/f_printer.c b/drivers/usb/gadget/function/f_printer.c index 44173df27273..a91c18a585b5 100644 --- a/drivers/usb/gadget/function/f_printer.c +++ b/drivers/usb/gadget/function/f_printer.c @@ -804,6 +804,8 @@ done: static void printer_reset_interface(struct printer_dev *dev) { + unsigned long flags; + if (dev->interface < 0) return; @@ -815,9 +817,11 @@ static void printer_reset_interface(struct printer_dev *dev) if (dev->out_ep->desc) usb_ep_disable(dev->out_ep); + spin_lock_irqsave(&dev->lock, flags); dev->in_ep->desc = NULL; dev->out_ep->desc = NULL; dev->interface = -1; + spin_unlock_irqrestore(&dev->lock, flags); } /* Change our operational Interface. */ @@ -1131,13 +1135,10 @@ static int printer_func_set_alt(struct usb_function *f, static void printer_func_disable(struct usb_function *f) { struct printer_dev *dev = func_to_printer(f); - unsigned long flags; DBG(dev, "%s\n", __func__); - spin_lock_irqsave(&dev->lock, flags); printer_reset_interface(dev); - spin_unlock_irqrestore(&dev->lock, flags); } static inline struct f_printer_opts |