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* [bug report] usb: gadget: bdc: use readl_poll_timeout() to simplify code
@ 2021-07-27  8:42 Dan Carpenter
  0 siblings, 0 replies; only message in thread
From: Dan Carpenter @ 2021-07-27  8:42 UTC (permalink / raw)
  To:; +Cc: linux-usb

Hello Chunfeng Yun,

The patch 75ae051efc9b: "usb: gadget: bdc: use readl_poll_timeout()
to simplify code" from Jul 13, 2020, leads to the following static
checker warning:

	drivers/usb/gadget/udc/bdc/bdc_core.c:38 poll_oip()
	warn: sleeping in atomic context

    33 static int poll_oip(struct bdc *bdc, u32 usec)
    34 {
    35 	u32 status;
    36 	int ret;
--> 38 	ret = readl_poll_timeout(bdc->regs + BDC_BDCSC, status,
    39 				 (BDC_CSTS(status) != BDC_OIP), 10, usec);
This adds a 10us sleep, but we're holding a spin lock so it's a sleeping
in atomic bug.  One call tree is:

bdc_udc_stop() <-- takes a spin lock
  --> bdc_stop
      --> poll_oip() <-- sleep

    40 	if (ret)
    41 		dev_err(bdc->dev, "operation timedout BDCSC: 0x%08x\n", status);
    42 	else
    43 		dev_dbg(bdc->dev, "%s complete status=%d", __func__, BDC_CSTS(status));
    45 	return ret;
    46 }

dan carpenter

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