[PATCH] net: qrtr: use protocol endiannes variable

[PATCH] net: qrtr: use protocol endiannes variable

[Nicholas Mc Guire]

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

Re: [PATCH] net: qrtr: use protocol endiannes variable

[David Miller]

From: Nicholas Mc Guire <hofrat@osadl.org>
Date: Fri, 10 May 2019 03:08:53 +0200

> 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;

Please try to preserve as much of the reverse chrimstas tree here rather
than making it worse.

Thank you.

Re: [PATCH] net: qrtr: use protocol endiannes variable

[Nicholas Mc Guire]

On Fri, May 10, 2019 at 01:28:00PM -0700, David Miller wrote:
> From: Nicholas Mc Guire <hofrat@osadl.org>
> Date: Fri, 10 May 2019 03:08:53 +0200
> 
> > 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;
> 
> Please try to preserve as much of the reverse chrimstas tree here rather
> than making it worse.
>
sorry - did not really think about that at all  - will re-order the declarations and resend

thx!
hofrat