diff options
| author | Iago Abal <mail@iagoabal.eu> | 2016-06-21 13:01:11 +0300 |
|---|---|---|
| committer | Felipe Balbi <felipe.balbi@linux.intel.com> | 2016-06-21 13:18:23 +0300 |
| commit | 1d23d16a88e6c8143b07339435ba061b131ebb8c (patch) | |
| tree | b75774f24a265c62d78ca54b1778115b1d4e0419 /drivers/usb/gadget/udc/pch_udc.c | |
| parent | 43202800010102a857ffb119429d7dc5b41b7096 (diff) | |
| download | linux-1d23d16a88e6c8143b07339435ba061b131ebb8c.tar.xz | |
usb: gadget: pch_udc: reorder spin_[un]lock to avoid deadlock
The above commit reordered spin_lock/unlock and now `&dev->lock' is acquired
(rather than released) before calling `dev->driver->disconnect',
`dev->driver->setup', `dev->driver->suspend', `usb_gadget_giveback_request', and
`usb_gadget_udc_reset'.
But this *may* not be the right way to fix the problem pointed by d3cb25a12138.
Note that the other usb/gadget/udc drivers do release the lock before calling
these functions. There are also inconsistencies within pch_udc.c, where
`dev->driver->disconnect' is called while holding `&dev->lock' in lines 613 and
1184, but not in line 2739.
Finally, commit d3cb25a12138 may have introduced several potential deadlocks.
For instance, EBA (https://github.com/models-team/eba) reports:
Double lock in drivers/usb/gadget/udc/pch_udc.c
first at 2791: spin_lock(& dev->lock); [pch_udc_isr]
second at 2694: spin_lock(& dev->lock); [pch_udc_svc_cfg_interrupt]
after calling from 2793: pch_udc_dev_isr(dev, dev_intr);
after calling from 2724: pch_udc_svc_cfg_interrupt(dev);
Similarly, other potential deadlocks are 2791 -> 2793 -> 2721 -> 2657; and
2791 -> 2793 -> 2711 -> 2573 -> 1499 -> 1480.
Fixes: d3cb25a12138 ("usb: gadget: udc: fix spin_lock in pch_udc")
Signed-off-by: Iago Abal <mail@iagoabal.eu>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Diffstat (limited to 'drivers/usb/gadget/udc/pch_udc.c')
| -rw-r--r-- | drivers/usb/gadget/udc/pch_udc.c | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/drivers/usb/gadget/udc/pch_udc.c b/drivers/usb/gadget/udc/pch_udc.c index 8ad847a5d4e4..a97da645c1b9 100644 --- a/drivers/usb/gadget/udc/pch_udc.c +++ b/drivers/usb/gadget/udc/pch_udc.c @@ -1477,11 +1477,11 @@ static void complete_req(struct pch_udc_ep *ep, struct pch_udc_request *req, req->dma_mapped = 0; } ep->halted = 1; - spin_lock(&dev->lock); + spin_unlock(&dev->lock); if (!ep->in) pch_udc_ep_clear_rrdy(ep); usb_gadget_giveback_request(&ep->ep, &req->req); - spin_unlock(&dev->lock); + spin_lock(&dev->lock); ep->halted = halted; } @@ -2567,9 +2567,9 @@ static void pch_udc_svc_ur_interrupt(struct pch_udc_dev *dev) empty_req_queue(ep); } if (dev->driver) { - spin_lock(&dev->lock); - usb_gadget_udc_reset(&dev->gadget, dev->driver); spin_unlock(&dev->lock); + usb_gadget_udc_reset(&dev->gadget, dev->driver); + spin_lock(&dev->lock); } } @@ -2648,9 +2648,9 @@ static void pch_udc_svc_intf_interrupt(struct pch_udc_dev *dev) dev->ep[i].halted = 0; } dev->stall = 0; - spin_lock(&dev->lock); - dev->driver->setup(&dev->gadget, &dev->setup_data); spin_unlock(&dev->lock); + dev->driver->setup(&dev->gadget, &dev->setup_data); + spin_lock(&dev->lock); } /** @@ -2685,9 +2685,9 @@ static void pch_udc_svc_cfg_interrupt(struct pch_udc_dev *dev) dev->stall = 0; /* call gadget zero with setup data received */ - spin_lock(&dev->lock); - dev->driver->setup(&dev->gadget, &dev->setup_data); spin_unlock(&dev->lock); + dev->driver->setup(&dev->gadget, &dev->setup_data); + spin_lock(&dev->lock); } /** |