Hi Minas,

url:    
https://github.com/0day-ci/linux/commits/Minas-Harutyunyan/usb-dwc2-Disable-all-EP-s-on-disconnect/20180919-104259
base:   https://git.kernel.org/pub/scm/linux/kernel/git/balbi/usb.git next

smatch warnings:
drivers/usb/dwc2/gadget.c:4024 dwc2_hsotg_ep_disable() error: double unlock 
'spin_lock:&hsotg->lock'
drivers/usb/dwc2/gadget.c:4350 dwc2_hsotg_udc_stop() error: double unlock 
'spin_lock:&hsotg->lock'

# 
https://github.com/0day-ci/linux/commit/a4705c3fee2053e95791210eb435a04b665f6dc3
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout a4705c3fee2053e95791210eb435a04b665f6dc3
vim +4024 drivers/usb/dwc2/gadget.c

5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  3993  
8b9bc4608 drivers/usb/gadget/s3c-hsotg.c Lukasz Majewski    2012-05-04  3994  
/**
1f91b4cc0 drivers/usb/dwc2/gadget.c      Felipe Balbi       2015-08-06  3995   
* dwc2_hsotg_ep_disable - disable given endpoint
8b9bc4608 drivers/usb/gadget/s3c-hsotg.c Lukasz Majewski    2012-05-04  3996   
* @ep: The endpoint to disable.
8b9bc4608 drivers/usb/gadget/s3c-hsotg.c Lukasz Majewski    2012-05-04  3997   
*/
1f91b4cc0 drivers/usb/dwc2/gadget.c      Felipe Balbi       2015-08-06  3998  
static int dwc2_hsotg_ep_disable(struct usb_ep *ep)
5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  3999  {
1f91b4cc0 drivers/usb/dwc2/gadget.c      Felipe Balbi       2015-08-06  4000    
struct dwc2_hsotg_ep *hs_ep = our_ep(ep);
941fcce4f drivers/usb/dwc2/gadget.c      Dinh Nguyen        2014-11-11  4001    
struct dwc2_hsotg *hsotg = hs_ep->parent;
5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  4002    
int dir_in = hs_ep->dir_in;
5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  4003    
int index = hs_ep->index;
5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  4004    
unsigned long flags;
5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  4005    
u32 epctrl_reg;
5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  4006    
u32 ctrl;
a4705c3fe drivers/usb/dwc2/gadget.c      Minas Harutyunyan  2018-09-18  4007    
int locked;
5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  4008  
1e0112937 drivers/usb/dwc2/gadget.c      Marek Szyprowski   2014-09-09  4009    
dev_dbg(hsotg->dev, "%s(ep %p)\n", __func__, ep);
5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  4010  
c6f5c050e drivers/usb/dwc2/gadget.c      Mian Yousaf Kaukab 2015-01-09  4011    
if (ep == &hsotg->eps_out[0]->ep) {
5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  4012    
        dev_err(hsotg->dev, "%s: called for ep0\n", __func__);
5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  4013    
        return -EINVAL;
9b481092c drivers/usb/dwc2/gadget.c      John Stultz        2017-10-23  4014    
}
9b481092c drivers/usb/dwc2/gadget.c      John Stultz        2017-10-23  4015  
9b481092c drivers/usb/dwc2/gadget.c      John Stultz        2017-10-23  4016    
if (hsotg->op_state != OTG_STATE_B_PERIPHERAL) {
9b481092c drivers/usb/dwc2/gadget.c      John Stultz        2017-10-23  4017    
        dev_err(hsotg->dev, "%s: called in host mode?\n", __func__);
9b481092c drivers/usb/dwc2/gadget.c      John Stultz        2017-10-23  4018    
        return -EINVAL;
5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  4019    
}
5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  4020  
94cb8fd63 drivers/usb/gadget/s3c-hsotg.c Lukasz Majewski    2012-05-04  4021    
epctrl_reg = dir_in ? DIEPCTL(index) : DOEPCTL(index);
5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  4022  
a4705c3fe drivers/usb/dwc2/gadget.c      Minas Harutyunyan  2018-09-18  4023    
locked = spin_trylock(&hsotg->lock);
a4705c3fe drivers/usb/dwc2/gadget.c      Minas Harutyunyan  2018-09-18 @4024    
spin_unlock(&hsotg->lock);
5ad1d3160 drivers/usb/gadget/s3c-hsotg.c Lukasz Majewski    2012-06-14  4025    
spin_lock_irqsave(&hsotg->lock, flags);


This is obviously deliberate that we drop the other thread's lock and
then take it ourselves.  But I don't think that can be right at all.
How do we know that it's safe for the other thread to drop the lock?

There should at least be a long comment in front of the code explaining
why it's safe to steal the lock like this.


5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  4026  
f25c42b8d drivers/usb/dwc2/gadget.c      Gevorg Sahakyan    2018-07-26  4027    
ctrl = dwc2_readl(hsotg, epctrl_reg);
a4f827714 drivers/usb/dwc2/gadget.c      Vahram Aharonyan   2016-11-14  4028  
a4f827714 drivers/usb/dwc2/gadget.c      Vahram Aharonyan   2016-11-14  4029    
if (ctrl & DXEPCTL_EPENA)
a4f827714 drivers/usb/dwc2/gadget.c      Vahram Aharonyan   2016-11-14  4030    
        dwc2_hsotg_ep_stop_xfr(hsotg, hs_ep);
a4f827714 drivers/usb/dwc2/gadget.c      Vahram Aharonyan   2016-11-14  4031  
47a1685f1 drivers/usb/dwc2/gadget.c      Dinh Nguyen        2014-04-14  4032    
ctrl &= ~DXEPCTL_EPENA;
47a1685f1 drivers/usb/dwc2/gadget.c      Dinh Nguyen        2014-04-14  4033    
ctrl &= ~DXEPCTL_USBACTEP;
47a1685f1 drivers/usb/dwc2/gadget.c      Dinh Nguyen        2014-04-14  4034    
ctrl |= DXEPCTL_SNAK;
5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  4035  
5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  4036    
dev_dbg(hsotg->dev, "%s: DxEPCTL=0x%08x\n", __func__, ctrl);
f25c42b8d drivers/usb/dwc2/gadget.c      Gevorg Sahakyan    2018-07-26  4037    
dwc2_writel(hsotg, ctrl, epctrl_reg);
5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  4038  
5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  4039    
/* disable endpoint interrupts */
1f91b4cc0 drivers/usb/dwc2/gadget.c      Felipe Balbi       2015-08-06  4040    
dwc2_hsotg_ctrl_epint(hsotg, hs_ep->index, hs_ep->dir_in, 0);
5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  4041  
1141ea01d drivers/usb/dwc2/gadget.c      Mian Yousaf Kaukab 2015-01-09  4042    
/* terminate all requests with shutdown */
1141ea01d drivers/usb/dwc2/gadget.c      Mian Yousaf Kaukab 2015-01-09  4043    
kill_all_requests(hsotg, hs_ep, -ESHUTDOWN);
1141ea01d drivers/usb/dwc2/gadget.c      Mian Yousaf Kaukab 2015-01-09  4044  
1c07b20ea drivers/usb/dwc2/gadget.c      Robert Baldyga     2016-08-29  4045    
hsotg->fifo_map &= ~(1 << hs_ep->fifo_index);
1c07b20ea drivers/usb/dwc2/gadget.c      Robert Baldyga     2016-08-29  4046    
hs_ep->fifo_index = 0;
1c07b20ea drivers/usb/dwc2/gadget.c      Robert Baldyga     2016-08-29  4047    
hs_ep->fifo_size = 0;
1c07b20ea drivers/usb/dwc2/gadget.c      Robert Baldyga     2016-08-29  4048  
22258f490 drivers/usb/gadget/s3c-hsotg.c Lukasz Majewski    2012-06-14  4049    
spin_unlock_irqrestore(&hsotg->lock, flags);
a4705c3fe drivers/usb/dwc2/gadget.c      Minas Harutyunyan  2018-09-18  4050    
if (!locked)
a4705c3fe drivers/usb/dwc2/gadget.c      Minas Harutyunyan  2018-09-18  4051    
        spin_lock(&hsotg->lock);
a4705c3fe drivers/usb/dwc2/gadget.c      Minas Harutyunyan  2018-09-18  4052  
5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  4053    
return 0;
5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  4054  }
5b7d70c6d drivers/usb/gadget/s3c-hsotg.c Ben Dooks          2009-06-02  4055  

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