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From: Nicholas Mc Guire <hofrat@osadl.org>
To: "David S. Miller" <davem@davemloft.net>
Cc: Arun Kumar Neelakantam <aneela@codeaurora.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	David Hildenbrand <david@redhat.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Johannes Berg <johannes.berg@intel.com>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	Nicholas Mc Guire <hofrat@osadl.org>
Subject: [PATCH] net: qrtr: use protocol endiannes variable
Date: Fri, 10 May 2019 03:08:53 +0200	[thread overview]
Message-ID: <1557450533-9321-1-git-send-email-hofrat@osadl.org> (raw)

sparse was unable to verify endianness correctness due to reassignment
from le32_to_cpu to the same variable - fix this warning up by providing
a proper __le32 type and initializing it. This is not actually fixing
any bug - rather just addressing the sparse warning.

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
---

Problem located by an experimental coccinelle script to locate
patters that make sparse unhappy (false positives):

sparse was unhappy about:
net/qrtr/qrtr.c:811:24: warning: cast to restricted __le32

The patch does change the binary - from inspection of the .lst files
it seems that the additional variable as well instruction reordering
constraints change the code even if the code-logic is the same.

Patch was compile-tested with: qcom_defconfig + QRTR=m

Patch is against 5.1 (localversion-next is next-20190509)

 net/qrtr/qrtr.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/qrtr/qrtr.c b/net/qrtr/qrtr.c
index dd0e97f..c90edaa 100644
--- a/net/qrtr/qrtr.c
+++ b/net/qrtr/qrtr.c
@@ -733,7 +733,8 @@ static int qrtr_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
 	struct qrtr_node *node;
 	struct sk_buff *skb;
 	size_t plen;
-	u32 type = QRTR_TYPE_DATA;
+	u32 type = 0;
+	__le32 qrtr_type = cpu_to_le32(QRTR_TYPE_DATA);
 	int rc;
 
 	if (msg->msg_flags & ~(MSG_DONTWAIT))
@@ -807,8 +808,8 @@ static int qrtr_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
 		}
 
 		/* control messages already require the type as 'command' */
-		skb_copy_bits(skb, 0, &type, 4);
-		type = le32_to_cpu(type);
+		skb_copy_bits(skb, 0, &qrtr_type, 4);
+		type = le32_to_cpu(qrtr_type);
 	}
 
 	rc = enqueue_fn(node, skb, type, &ipc->us, addr);
-- 
2.1.4


             reply	other threads:[~2019-05-10  1:15 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-10  1:08 Nicholas Mc Guire [this message]
2019-05-10 20:28 ` David Miller
2019-05-11  0:17   ` Nicholas Mc Guire

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