linux-kernel - [PATCH 1/2] usb: gadget: r8a66597: Fix two possible sleep-in-atomic-context bugs in init

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Message-Id: <20180620035453.7721-1-baijiaju1990@gmail.com>
Date:   Wed, 20 Jun 2018 11:54:53 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     balbi@...nel.org, gregkh@...uxfoundation.org,
        nicolas.ferre@...rochip.com, keescook@...omium.org,
        robert.jarzmik@...e.fr, allen.lkml@...il.com
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH 1/2] usb: gadget: r8a66597: Fix two possible sleep-in-atomic-context bugs in init_controller()

The driver may sleep with holding a spinlock.
The function call paths (from bottom to top) in Linux-4.16.7 are:

[FUNC] msleep
drivers/usb/gadget/udc/r8a66597-udc.c, 839: 
		msleep in init_controller
drivers/usb/gadget/udc/r8a66597-udc.c, 96: 
		init_controller in r8a66597_usb_disconnect
drivers/usb/gadget/udc/r8a66597-udc.c, 93: 
		spin_lock in r8a66597_usb_disconnect

[FUNC] msleep
drivers/usb/gadget/udc/r8a66597-udc.c, 835: 
		msleep in init_controller
drivers/usb/gadget/udc/r8a66597-udc.c, 96: 
		init_controller in r8a66597_usb_disconnect
drivers/usb/gadget/udc/r8a66597-udc.c, 93: 
		spin_lock in r8a66597_usb_disconnect

To fix these bugs, msleep() is replaced with mdelay().

This bug is found by my static analysis tool (DSAC-2) and checked by
my code review.

Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
---
 drivers/usb/gadget/udc/r8a66597-udc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/udc/r8a66597-udc.c b/drivers/usb/gadget/udc/r8a66597-udc.c
index a3ecce62662b..24ee9867964b 100644
--- a/drivers/usb/gadget/udc/r8a66597-udc.c
+++ b/drivers/usb/gadget/udc/r8a66597-udc.c
@@ -832,11 +832,11 @@ static void init_controller(struct r8a66597 *r8a66597)
 
 		r8a66597_bset(r8a66597, XCKE, SYSCFG0);
 
-		msleep(3);
+		mdelay(3);
 
 		r8a66597_bset(r8a66597, PLLC, SYSCFG0);
 
-		msleep(1);
+		mdelay(1);
 
 		r8a66597_bset(r8a66597, SCKE, SYSCFG0);
 
-- 
2.17.0