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authorIago Abal <mail@iagoabal.eu>2016-06-21 13:01:11 +0300
committerFelipe Balbi <felipe.balbi@linux.intel.com>2016-06-21 13:18:23 +0300
commit1d23d16a88e6c8143b07339435ba061b131ebb8c (patch)
treeb75774f24a265c62d78ca54b1778115b1d4e0419 /drivers/usb/gadget/udc
parent43202800010102a857ffb119429d7dc5b41b7096 (diff)
downloadlinux-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')
-rw-r--r--drivers/usb/gadget/udc/pch_udc.c16
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);
}
/**