linux-kernel - [PATCH v2] block: paride: on26: Replace mdelay with msleep in on26_test

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Date:   Sat, 27 Jan 2018 16:25:57 +0800
From:   Jia-Ju Bai <baijiaju1990@...il.com>
To:     tim@...erelk.net, viro@...IV.linux.org.uk
Cc:     linux-kernel@...r.kernel.org, Jia-Ju Bai <baijiaju1990@...il.com>
Subject: [PATCH v2] block: paride: on26: Replace mdelay with msleep in on26_test_port

on26_test_port() is never called from atomic context.

It has no direct callers and it is called only via function pointer 
"->test_port" that is only used in pi_probe_unit():
drivers/block/paride/paride.c:322: max = pi->proto->test_port(pi);
That gets called only from pi_init(), called from
p{d,cd,f,t,g}_detect(), called from module_init stuff, all of the above
without entering atomic context along the way.

Despite never getting called from atomic context, on26_test_port() calls
mdelay(100), i.e. busy wait for 100ms.
That is not necessary and can be replaced with msleep to avoid busy wait.

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

Signed-off-by: Jia-Ju Bai <baijiaju1990@...il.com>
---
v2:
* Revise the description.
  Thanks Al for helpful advice.

---
 drivers/block/paride/on26.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/paride/on26.c b/drivers/block/paride/on26.c
index 95ba256..3240d6f 100644
--- a/drivers/block/paride/on26.c
+++ b/drivers/block/paride/on26.c
@@ -163,7 +163,7 @@ static int on26_test_port( PIA *pi)  /* hard reset */
                 on26_write_regr(pi,0,6,0xb0);
                 y = on26_read_regr(pi,0,7);
                 if (!((x&0x80)||(y&0x80))) break;
-                mdelay(100);
+                msleep(100);
             }

 	    if (i == RESET_WAIT) 
-- 
1.7.9.5