linux-kernel - [PATCH] staging: ks7010: Replace mdelay with usleep_range in ks7010_upload

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Date:   Tue, 10 Apr 2018 16:58:54 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     gregkh@...uxfoundation.org, me@...in.cc
Cc:     devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH] staging: ks7010: Replace mdelay with usleep_range in ks7010_upload_firmware

ks7010_upload_firmware() is never called in atomic context.

The call chain ending up at ks7010_upload_firmware() is:
[1] ks7010_upload_firmware() <- ks7010_sdio_probe()

ks7010_sdio_probe() is set as ".probe" in struct sdio_driver.
This function is not called in atomic context.

Despite never getting called from atomic context, ks7010_upload_firmware()
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@...il.com>
---
 drivers/staging/ks7010/ks7010_sdio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/ks7010/ks7010_sdio.c b/drivers/staging/ks7010/ks7010_sdio.c
index 8cfdff1..8d7bc26 100644
--- a/drivers/staging/ks7010/ks7010_sdio.c
+++ b/drivers/staging/ks7010/ks7010_sdio.c
@@ -719,7 +719,7 @@ static int ks7010_upload_firmware(struct ks_sdio_card *card)
 
 	/* Firmware running check */
 	for (n = 0; n < 50; ++n) {
-		mdelay(10);	/* wait_ms(10); */
+		usleep_range(10000, 11000);	/* wait_ms(10); */
 		ret = ks7010_sdio_readb(priv, GCR_A, &byte);
 		if (ret)
 			goto release_firmware;
-- 
1.9.1