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From: Dan Carpenter <dan.carpenter@oracle.com>
To: chunfeng.yun@mediatek.com
Cc: linux-usb@vger.kernel.org
Subject: [bug report] usb: gadget: bdc: use readl_poll_timeout() to simplify code
Date: Tue, 27 Jul 2021 11:42:08 +0300	[thread overview]
Message-ID: <20210727084208.GA19962@kili> (raw)

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

drivers/usb/gadget/udc/bdc/bdc_core.c
    33 static int poll_oip(struct bdc *bdc, u32 usec)
    34 {
    35 	u32 status;
    36 	int ret;
    37 
--> 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));
    44 
    45 	return ret;
    46 }

regards,
dan carpenter

                 reply	other threads:[~2021-07-27  8:42 UTC|newest]

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