linux-kernel - [PATCH] staging: fsl-mc/dpio: Fix incorrect comparison

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Date:   Wed, 27 Sep 2017 12:57:28 -0500
From:   Ioana Radulescu <ruxandra.radulescu@....com>
To:     <gregkh@...uxfoundation.org>
CC:     <devel@...verdev.osuosl.org>, <linux-kernel@...r.kernel.org>,
        <agraf@...e.de>, <arnd@...db.de>, <bogdan.purcareata@....com>,
        <stuyoder@...il.com>, <laurentiu.tudor@....com>,
        <ruxandra.radulescu@....com>, <roy.pledge@....com>
Subject: [PATCH] staging: fsl-mc/dpio: Fix incorrect comparison

For some dpio functions, a negative cpu id parameter value is
valid and means "any". But when trying to validate this param
value against an upper limit, in this case num_possible_cpus(),
we risk obtaining the wrong result due to an implicit cast
to unsigned.

Avoid an incorrect check result when cpu id is negative, by
explicitly stating the comparison is between signed values.

Signed-off-by: Ioana Radulescu <ruxandra.radulescu@....com>
---
 drivers/staging/fsl-mc/bus/dpio/dpio-service.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/fsl-mc/bus/dpio/dpio-service.c b/drivers/staging/fsl-mc/bus/dpio/dpio-service.c
index f809682..26922fc 100644
--- a/drivers/staging/fsl-mc/bus/dpio/dpio-service.c
+++ b/drivers/staging/fsl-mc/bus/dpio/dpio-service.c
@@ -76,7 +76,7 @@ static inline struct dpaa2_io *service_select_by_cpu(struct dpaa2_io *d,
 	if (d)
 		return d;
 
-	if (unlikely(cpu >= num_possible_cpus()))
+	if (unlikely(cpu >= (int)num_possible_cpus()))
 		return NULL;
 
 	/*
@@ -121,7 +121,7 @@ struct dpaa2_io *dpaa2_io_create(const struct dpaa2_io_desc *desc)
 		return NULL;
 
 	/* check if CPU is out of range (-1 means any cpu) */
-	if (desc->cpu >= num_possible_cpus()) {
+	if (desc->cpu >= (int)num_possible_cpus()) {
 		kfree(obj);
 		return NULL;
 	}
-- 
2.7.4