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| author | Radoslav Gerganov <rgerganov@vmware.com> | 2019-03-05 10:10:34 +0000 |
|---|---|---|
| committer | Felipe Balbi <felipe.balbi@linux.intel.com> | 2019-03-20 10:58:48 +0200 |
| commit | 072684e8c58d17e853f8e8b9f6d9ce2e58d2b036 (patch) | |
| tree | 829c8ca42b08f53db0733dcb6abe376dc8ef576f /drivers/usb/gadget/function/f_hid.c | |
| parent | 091dacc3cc10979ab0422f0a9f7fcc27eee97e69 (diff) | |
| download | lwn-072684e8c58d17e853f8e8b9f6d9ce2e58d2b036.tar.gz lwn-072684e8c58d17e853f8e8b9f6d9ce2e58d2b036.zip | |
USB: gadget: f_hid: fix deadlock in f_hidg_write()
In f_hidg_write() the write_spinlock is acquired before calling
usb_ep_queue() which causes a deadlock when dummy_hcd is being used.
This is because dummy_queue() callbacks into f_hidg_req_complete() which
tries to acquire the same spinlock. This is (part of) the backtrace when
the deadlock occurs:
0xffffffffc06b1410 in f_hidg_req_complete
0xffffffffc06a590a in usb_gadget_giveback_request
0xffffffffc06cfff2 in dummy_queue
0xffffffffc06a4b96 in usb_ep_queue
0xffffffffc06b1eb6 in f_hidg_write
0xffffffff8127730b in __vfs_write
0xffffffff812774d1 in vfs_write
0xffffffff81277725 in SYSC_write
Fix this by releasing the write_spinlock before calling usb_ep_queue()
Reviewed-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Tested-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: stable@vger.kernel.org # 4.11+
Fixes: 749494b6bdbb ("usb: gadget: f_hid: fix: Move IN request allocation to set_alt()")
Signed-off-by: Radoslav Gerganov <rgerganov@vmware.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Diffstat (limited to 'drivers/usb/gadget/function/f_hid.c')
| -rw-r--r-- | drivers/usb/gadget/function/f_hid.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/usb/gadget/function/f_hid.c b/drivers/usb/gadget/function/f_hid.c index 75b113a5b25c..f3816a5c861e 100644 --- a/drivers/usb/gadget/function/f_hid.c +++ b/drivers/usb/gadget/function/f_hid.c @@ -391,20 +391,20 @@ try_again: req->complete = f_hidg_req_complete; req->context = hidg; + spin_unlock_irqrestore(&hidg->write_spinlock, flags); + status = usb_ep_queue(hidg->in_ep, req, GFP_ATOMIC); if (status < 0) { ERROR(hidg->func.config->cdev, "usb_ep_queue error on int endpoint %zd\n", status); - goto release_write_pending_unlocked; + goto release_write_pending; } else { status = count; } - spin_unlock_irqrestore(&hidg->write_spinlock, flags); return status; release_write_pending: spin_lock_irqsave(&hidg->write_spinlock, flags); -release_write_pending_unlocked: hidg->write_pending = 0; spin_unlock_irqrestore(&hidg->write_spinlock, flags); |