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From: Jia-Ju Bai <baijiaju1990@gmail.com>
To: samuel@sortiz.org, gregkh@linuxfoundation.org,
	davem@davemloft.net, johan@kernel.org, arvind.yadav.cs@gmail.com
Cc: netdev@vger.kernel.org, devel@driverdev.osuosl.org,
	linux-kernel@vger.kernel.org, Jia-Ju Bai <baijiaju1990@gmail.com>
Subject: [PATCH 1/2] staging: irda: Replace mdelay with usleep_range in stir421x_fw_upload
Date: Wed, 11 Apr 2018 09:29:34 +0800	[thread overview]
Message-ID: <1523410174-1553-1-git-send-email-baijiaju1990@gmail.com> (raw)

stir421x_fw_upload() is never called in atomic context.

The call chain ending up at stir421x_fw_upload() is:
[1] stir421x_fw_upload() <- stir421x_patch_device() <- irda_usb_probe()

irda_usb_probe() is set as ".probe" in struct usb_driver.
This function is not called in atomic context.

Despite never getting called from atomic context, stir421x_fw_upload()
calls mdelay() to busily wait.
This is not necessary and can be replaced with usleep_range() to
avoid busy waiting.

This is found by a static analysis tool named DCNS written by myself.
And I also manually check it.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
---
 drivers/staging/irda/drivers/irda-usb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/irda/drivers/irda-usb.c b/drivers/staging/irda/drivers/irda-usb.c
index 723e49b..c6c8c2c 100644
--- a/drivers/staging/irda/drivers/irda-usb.c
+++ b/drivers/staging/irda/drivers/irda-usb.c
@@ -1050,7 +1050,7 @@ static int stir421x_fw_upload(struct irda_usb_cb *self,
 		if (ret < 0)
 			break;
 
-		mdelay(10);
+		usleep_range(10000, 11000);
 	}
 
 	kfree(patch_block);
-- 
1.9.1

             reply	other threads:[~2018-04-11  1:29 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-11  1:29 Jia-Ju Bai [this message]
2018-04-11  6:41 ` [PATCH 1/2] staging: irda: Replace mdelay with usleep_range in stir421x_fw_upload Greg KH
2018-04-11  7:17   ` Jia-Ju Bai
2018-04-11  8:03     ` Greg KH
2018-04-11  8:11       ` Jia-Ju Bai
2018-04-11  8:17         ` Greg KH
2018-04-11  8:20           ` Jia-Ju Bai
2018-04-11 14:26             ` David Miller
2018-04-11 14:30               ` Jia-Ju Bai
2018-04-11  7:07 ` Johan Hovold

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