[v2] USB: usbtmc: Fix RCU stall warning

Commit Message

Zhang, Qiang July 23, 2021, 12:43 a.m. UTC

From: Qiang.zhang <[e-mail]>

rcu: INFO: rcu_preempt self-detected stall on CPU
rcu:    1-...!: (2 ticks this GP) idle=d92/1/0x4000000000000000
        softirq=25390/25392 fqs=3
        (t=12164 jiffies g=31645 q=43226)
rcu: rcu_preempt kthread starved for 12162 jiffies! g31645 f0x0
     RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu:    Unless rcu_preempt kthread gets sufficient CPU time,
        OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:R  running task
...........
usbtmc 3-1:0.0: unknown status received: -71
usbtmc 3-1:0.0: unknown status received: -71
usbtmc 3-1:0.0: unknown status received: -71
usbtmc 3-1:0.0: unknown status received: -71
usbtmc 3-1:0.0: unknown status received: -71
usbtmc 3-1:0.0: unknown status received: -71
usbtmc 3-1:0.0: unknown status received: -71
usbtmc 3-1:0.0: unknown status received: -71
usbtmc 3-1:0.0: usb_submit_urb failed: -19

The function usbtmc_interrupt() resubmits urbs when the error status
of an urb is -EPROTO. In systems using the dummy_hcd usb controller
this can result in endless interrupt loops when the usbtmc device is
disconnected from the host system.

Since host controller drivers already try to recover from transmission
errors, there is no need to resubmit the urb or try other solutions
to repair the error situation.

In case of errors the INT pipe just stops to wait for further packets.

Fixes: dbf3e7f654c0 ("Implement an ioctl to support the USMTMC-USB488 READ_STATUS_BYTE operation")
Cc: [e-mail]
Reported-by: [e-mail]
Signed-off-by: Qiang.zhang <[e-mail]>
---
 v1->v2:
 Add fixes and stable tags, modify description information.  

 drivers/usb/class/usbtmc.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

Patch

diff --git a/drivers/usb/class/usbtmc.c b/drivers/usb/class/usbtmc.c
index 74d5a9c5238a..73f419adce61 100644
--- a/drivers/usb/class/usbtmc.c
+++ b/drivers/usb/class/usbtmc.c
@@ -2324,17 +2324,10 @@  static void usbtmc_interrupt(struct urb *urb)
 		dev_err(dev, "overflow with length %d, actual length is %d\n",
 			data->iin_wMaxPacketSize, urb->actual_length);
 		fallthrough;
-	case -ECONNRESET:
-	case -ENOENT:
-	case -ESHUTDOWN:
-	case -EILSEQ:
-	case -ETIME:
-	case -EPIPE:
+	default:
 		/* urb terminated, clean up */
 		dev_dbg(dev, "urb terminated, status: %d\n", status);
 		return;
-	default:
-		dev_err(dev, "unknown status received: %d\n", status);
 	}
 exit:
 	rv = usb_submit_urb(urb, GFP_ATOMIC);