linux-kernel - [PATCH 4.9 096/218] powerpc/sysdev: fix incorrect use to determine if list is empty

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Date:   Mon, 18 Apr 2022 14:12:42 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jakob Koschel <jakobkoschel@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.9 096/218] powerpc/sysdev: fix incorrect use to determine if list is empty

From: Jakob Koschel <jakobkoschel@...il.com>

[ Upstream commit fa1321b11bd01752f5be2415e74a0e1a7c378262 ]

'gtm' will *always* be set by list_for_each_entry().
It is incorrect to assume that the iterator value will be NULL if the
list is empty.

Instead of checking the pointer it should be checked if
the list is empty.

Fixes: 83ff9dcf375c ("powerpc/sysdev: implement FSL GTM support")
Signed-off-by: Jakob Koschel <jakobkoschel@...il.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Link: https://lore.kernel.org/r/20220228142434.576226-1-jakobkoschel@gmail.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/powerpc/sysdev/fsl_gtm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/sysdev/fsl_gtm.c b/arch/powerpc/sysdev/fsl_gtm.c
index a6f0b96ce2c9..97dee7c99aa0 100644
--- a/arch/powerpc/sysdev/fsl_gtm.c
+++ b/arch/powerpc/sysdev/fsl_gtm.c
@@ -90,7 +90,7 @@ static LIST_HEAD(gtms);
  */
 struct gtm_timer *gtm_get_timer16(void)
 {
-	struct gtm *gtm = NULL;
+	struct gtm *gtm;
 	int i;
 
 	list_for_each_entry(gtm, &gtms, list_node) {
@@ -107,7 +107,7 @@ struct gtm_timer *gtm_get_timer16(void)
 		spin_unlock_irq(&gtm->lock);
 	}
 
-	if (gtm)
+	if (!list_empty(&gtms))
 		return ERR_PTR(-EBUSY);
 	return ERR_PTR(-ENODEV);
 }
-- 
2.34.1