linux-kernel - [PATCH v2] kdb: remove unnecessary null check of dbg_io

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Date:   Mon, 29 Jun 2020 23:50:13 +0300
From:   Cengiz Can <cengiz@...nel.wtf>
To:     daniel.thompson@...aro.org
Cc:     andriy.shevchenko@...ux.intel.com, cengiz@...nel.wtf,
        dianders@...omium.org, jason.wessel@...driver.com,
        kgdb-bugreport@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
        pmladek@...e.com, sumit.garg@...aro.org
Subject: [PATCH v2] kdb: remove unnecessary null check of dbg_io_ops

`kdb_msg_write` operates on a global `struct kgdb_io *` called
`dbg_io_ops`.

It's initialized in `debug_core.c` and checked throughout the debug
flow.

There's a null check in `kdb_msg_write` which triggers static analyzers
and gives the (almost entirely wrong) impression that it can be null.

Coverity scanner caught this as CID 1465042.

I have removed the unnecessary null check and eliminated false-positive
forward null dereference warning.

Signed-off-by: Cengiz Can <cengiz@...nel.wtf>
---
 kernel/debug/kdb/kdb_io.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
index 683a799618ad..4ac59a4fbeec 100644
--- a/kernel/debug/kdb/kdb_io.c
+++ b/kernel/debug/kdb/kdb_io.c
@@ -549,14 +549,12 @@ static void kdb_msg_write(const char *msg, int msg_len)
 	if (msg_len == 0)
 		return;
 
-	if (dbg_io_ops) {
-		const char *cp = msg;
-		int len = msg_len;
+	const char *cp = msg;
+	int len = msg_len;
 
-		while (len--) {
-			dbg_io_ops->write_char(*cp);
-			cp++;
-		}
+	while (len--) {
+		dbg_io_ops->write_char(*cp);
+		cp++;
 	}
 
 	for_each_console(c) {
-- 
2.27.0