[PATCH 5.17 0640/1126] powerpc/sysdev: fix incorrect use to determine if list is empty

Greg Kroah-Hartman
2022-04-05T10:04:34Z

From: Jakob Koschel <jakobkoschel@gmail.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@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220228142434.576226-1-jakobkoschel@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.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 8963eaffb1b7..39186ad6b3c3 100644
--- a/arch/powerpc/sysdev/fsl_gtm.c
+++ b/arch/powerpc/sysdev/fsl_gtm.c
@@ -86,7 +86,7 @@ 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) {
@@ -103,7 +103,7 @@ 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