This is a note to let you know that I've just added the patch titled
usb: gadget: pch_udc: reorder spin_[un]lock to avoid deadlock
to the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
usb-gadget-pch_udc-reorder-spin_lock-to-avoid-deadlock.patch
and it can be found in the queue-4.7 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1d23d16a88e6c8143b07339435ba061b131ebb8c Mon Sep 17 00:00:00 2001
From: Iago Abal <mail@xxxxxxxxxxx>
Date: Tue, 21 Jun 2016 12:01:11 +0200
Subject: usb: gadget: pch_udc: reorder spin_[un]lock to avoid deadlock
From: Iago Abal <mail@xxxxxxxxxxx>
commit 1d23d16a88e6c8143b07339435ba061b131ebb8c upstream.
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@xxxxxxxxxxx>
Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/gadget/udc/pch_udc.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
--- 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_
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;
}
@@ -2573,9 +2573,9 @@ static void pch_udc_svc_ur_interrupt(str
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);
}
}
@@ -2654,9 +2654,9 @@ static void pch_udc_svc_intf_interrupt(s
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);
}
/**
@@ -2691,9 +2691,9 @@ static void pch_udc_svc_cfg_interrupt(st
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);
}
/**
Patches currently in stable-queue which might be from mail@xxxxxxxxxxx are
queue-4.7/usb-gadget-pch_udc-reorder-spin_lock-to-avoid-deadlock.patch
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