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usb: gadget: fix spinlock dead lock in gadgetfs 

[   40.467381] =============================================
[   40.473013] [ INFO: possible recursive locking detected ]
[   40.478651] 4.6.0-08691-g7f3db9a #37 Not tainted
[   40.483466] ---------------------------------------------
[   40.489098] usb/733 is trying to acquire lock:
[   40.493734]  (&(&dev->lock)->rlock){-.....}, at: [<bf129288>] ep0_complete+0x18/0xdc [gadgetfs]
[   40.502882]
[   40.502882] but task is already holding lock:
[   40.508967]  (&(&dev->lock)->rlock){-.....}, at: [<bf12a420>] ep0_read+0x20/0x5e0 [gadgetfs]
[   40.517811]
[   40.517811] other info that might help us debug this:
[   40.524623]  Possible unsafe locking scenario:
[   40.524623]
[   40.530798]        CPU0
[   40.533346]        ----
[   40.535894]   lock(&(&dev->lock)->rlock);
[   40.540088]   lock(&(&dev->lock)->rlock);
[   40.544284]
[   40.544284]  *** DEADLOCK ***
[   40.544284]
[   40.550461]  May be due to missing lock nesting notation
[   40.550461]
[   40.557544] 2 locks held by usb/733:
[   40.561271]  #0:  (&f->f_pos_lock){+.+.+.}, at: [<c02a6114>] __fdget_pos+0x40/0x48
[   40.569219]  #1:  (&(&dev->lock)->rlock){-.....}, at: [<bf12a420>] ep0_read+0x20/0x5e0 [gadgetfs]
[   40.578523]
[   40.578523] stack backtrace:
[   40.583075] CPU: 0 PID: 733 Comm: usb Not tainted 4.6.0-08691-g7f3db9a #37
[   40.590246] Hardware name: Generic AM33XX (Flattened Device Tree)
[   40.596625] [<c010ffbc>] (unwind_backtrace) from [<c010c1bc>] (show_stack+0x10/0x14)
[   40.604718] [<c010c1bc>] (show_stack) from [<c04207fc>] (dump_stack+0xb0/0xe4)
[   40.612267] [<c04207fc>] (dump_stack) from [<c01886ec>] (__lock_acquire+0xf68/0x1994)
[   40.620440] [<c01886ec>] (__lock_acquire) from [<c0189528>] (lock_acquire+0xd8/0x238)
[   40.628621] [<c0189528>] (lock_acquire) from [<c06ad6b4>] (_raw_spin_lock_irqsave+0x38/0x4c)
[   40.637440] [<c06ad6b4>] (_raw_spin_lock_irqsave) from [<bf129288>] (ep0_complete+0x18/0xdc [gadgetfs])
[   40.647339] [<bf129288>] (ep0_complete [gadgetfs]) from [<bf10a728>] (musb_g_giveback+0x118/0x1b0 [musb_hdrc])
[   40.657842] [<bf10a728>] (musb_g_giveback [musb_hdrc]) from [<bf108768>] (musb_g_ep0_queue+0x16c/0x188 [musb_hdrc])
[   40.668772] [<bf108768>] (musb_g_ep0_queue [musb_hdrc]) from [<bf12a944>] (ep0_read+0x544/0x5e0 [gadgetfs])
[   40.678963] [<bf12a944>] (ep0_read [gadgetfs]) from [<c0284470>] (__vfs_read+0x20/0x110)
[   40.687414] [<c0284470>] (__vfs_read) from [<c0285324>] (vfs_read+0x88/0x114)
[   40.694864] [<c0285324>] (vfs_read) from [<c0286150>] (SyS_read+0x44/0x9c)
[   40.702051] [<c0286150>] (SyS_read) from [<c0107820>] (ret_fast_syscall+0x0/0x1c)

This is caused by the spinlock bug in ep0_read().
Fix the two other deadlock sources in gadgetfs_setup() too.

Cc: <stable@vger.kernel.org> # v3.16+
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
This commit is contained in:
Bin Liu 2016-05-26 11:43:45 -05:00 committed by Felipe Balbi
parent 0015f91560
commit d246dcb233
1 changed files with 13 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
drivers/usb/gadget/legacy/inode.c
View File

@ -938,8 +938,11 @@ ep0_read (struct file *fd, char __user *buf, size_t len, loff_t *ptr)
struct usb_ep *ep = dev->gadget->ep0;
struct usb_request *req = dev->req;
if ((retval = setup_req (ep, req, 0)) == 0)
retval = usb_ep_queue (ep, req, GFP_ATOMIC);
if ((retval = setup_req (ep, req, 0)) == 0) {
spin_unlock_irq (&dev->lock);
retval = usb_ep_queue (ep, req, GFP_KERNEL);
spin_lock_irq (&dev->lock);
}
dev->state = STATE_DEV_CONNECTED;
/* assume that was SET_CONFIGURATION */
@ -1457,8 +1460,11 @@ delegate:
w_length);
if (value < 0)
break;
spin_unlock (&dev->lock);
value = usb_ep_queue (gadget->ep0, dev->req,
GFP_ATOMIC);
GFP_KERNEL);
spin_lock (&dev->lock);
if (value < 0) {
clean_req (gadget->ep0, dev->req);
break;
@ -1481,11 +1487,14 @@ delegate:
if (value >= 0 && dev->state != STATE_DEV_SETUP) {
req->length = value;
req->zero = value < w_length;
value = usb_ep_queue (gadget->ep0, req, GFP_ATOMIC);
spin_unlock (&dev->lock);
value = usb_ep_queue (gadget->ep0, req, GFP_KERNEL);
if (value < 0) {
DBG (dev, "ep_queue --> %d\n", value);
req->status = 0;
}
return value;
}
/* device stalls when value < 0 */