linux-kernel - [PATCH] auxdisplay: charlcd: delete mdelay in long

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Date:   Fri, 26 Jan 2018 23:19:15 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     miguel.ojeda.sandonis@...il.com, w@....eu
Cc:     linux-kernel@...r.kernel.org, Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH] auxdisplay: charlcd: delete mdelay in long_sleep

The function long_sleep() calls mdelay() when in an interrupt handler.
But only charlcd_clear_display() and charlcd_init_display calls 
long_sleep(), and my tool finds that the two functions 
are never called in an interrupt handler.
Thus mdelay() and in_interrupt() are not necessary.

This is found by a static analysis tool named DCNS written by myself.

Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
---
 drivers/auxdisplay/charlcd.c |    5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/auxdisplay/charlcd.c b/drivers/auxdisplay/charlcd.c
index 642afd8..9e84795 100644
--- a/drivers/auxdisplay/charlcd.c
+++ b/drivers/auxdisplay/charlcd.c
@@ -102,10 +102,7 @@ struct charlcd_priv {
 /* sleeps that many milliseconds with a reschedule */
 static void long_sleep(int ms)
 {
-	if (in_interrupt())
-		mdelay(ms);
-	else
-		schedule_timeout_interruptible(msecs_to_jiffies(ms));
+	schedule_timeout_interruptible(msecs_to_jiffies(ms));
 }
 
 /* turn the backlight on or off */
-- 
1.7.9.5