Re: [PATCH 26/28] Avoid gcc 5.4 warning -Wunused-result

[Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>]

On Sun, Oct 09, 2016 at 04:31:17PM +0300, Yishai Hadas wrote:

> >-	if (write(connfd, msg, sizeof msg) != sizeof msg) {
> >-		fprintf(stderr, "Couldn't send local address\n");
> >+	if (write(connfd, msg, sizeof msg) != sizeof msg ||
> >+	    read(connfd, msg, sizeof msg) != sizeof msg) {
> >+		fprintf(stderr, "Couldn't send/recv local address\n");
> 
> At that step the server expects to read a "done" response from its client,
> checking whether the read was done for sizeof msg which is much larger will
> fail.

This OK?

>From db525af53140c3b7604ab45406ed8845cb6171e1 Mon Sep 17 00:00:00 2001
From: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
Date: Sun, 9 Oct 2016 17:17:54 -0600
Subject: [PATCH] verbs: Fix read error check in pingpong

Turns out these reads rely on the short readed caused by EOS.

Fixes: f3912df771db (Avoid gcc 5.4 warning -Wunused-result)
Signed-off-by: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
---
 libibverbs/examples/rc_pingpong.c  | 2 +-
 libibverbs/examples/srq_pingpong.c | 2 +-
 libibverbs/examples/uc_pingpong.c  | 2 +-
 libibverbs/examples/ud_pingpong.c  | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/libibverbs/examples/rc_pingpong.c b/libibverbs/examples/rc_pingpong.c
index c92e551c00e6..aca7bac4491b 100644
--- a/libibverbs/examples/rc_pingpong.c
+++ b/libibverbs/examples/rc_pingpong.c
@@ -309,7 +309,7 @@ static struct pingpong_dest *pp_server_exch_dest(struct pingpong_context *ctx,
 	sprintf(msg, "%04x:%06x:%06x:%s", my_dest->lid, my_dest->qpn,
 							my_dest->psn, gid);
 	if (write(connfd, msg, sizeof msg) != sizeof msg ||
-	    read(connfd, msg, sizeof msg) != sizeof msg) {
+	    read(connfd, msg, sizeof msg) != sizeof "done") {
 		fprintf(stderr, "Couldn't send/recv local address\n");
 		free(rem_dest);
 		rem_dest = NULL;
diff --git a/libibverbs/examples/srq_pingpong.c b/libibverbs/examples/srq_pingpong.c
index 863ff10dd0f4..8f55d78e87d4 100644
--- a/libibverbs/examples/srq_pingpong.c
+++ b/libibverbs/examples/srq_pingpong.c
@@ -333,7 +333,7 @@ static struct pingpong_dest *pp_server_exch_dest(struct pingpong_context *ctx,
 		}
 	}
 
-	if (read(connfd, msg, sizeof msg) != sizeof msg) {
+	if (read(connfd, msg, sizeof msg) != sizeof "done") {
 		perror("client write");
 		free(rem_dest);
 		rem_dest = NULL;
diff --git a/libibverbs/examples/uc_pingpong.c b/libibverbs/examples/uc_pingpong.c
index 2b105b947cf3..b565bacaff2a 100644
--- a/libibverbs/examples/uc_pingpong.c
+++ b/libibverbs/examples/uc_pingpong.c
@@ -283,7 +283,7 @@ static struct pingpong_dest *pp_server_exch_dest(struct pingpong_context *ctx,
 	sprintf(msg, "%04x:%06x:%06x:%s", my_dest->lid, my_dest->qpn,
 							my_dest->psn, gid);
 	if (write(connfd, msg, sizeof msg) != sizeof msg ||
-	    read(connfd, msg, sizeof msg) != sizeof msg) {
+	    read(connfd, msg, sizeof msg) != sizeof "done") {
 		fprintf(stderr, "Couldn't send/recv local address\n");
 		free(rem_dest);
 		rem_dest = NULL;
diff --git a/libibverbs/examples/ud_pingpong.c b/libibverbs/examples/ud_pingpong.c
index d0cd73cc0fae..ddb68cf8624b 100644
--- a/libibverbs/examples/ud_pingpong.c
+++ b/libibverbs/examples/ud_pingpong.c
@@ -280,7 +280,7 @@ static struct pingpong_dest *pp_server_exch_dest(struct pingpong_context *ctx,
 	sprintf(msg, "%04x:%06x:%06x:%s", my_dest->lid, my_dest->qpn,
 							my_dest->psn, gid);
 	if (write(connfd, msg, sizeof msg) != sizeof msg ||
-	    read(connfd, msg, sizeof msg) != sizeof msg) {
+	    read(connfd, msg, sizeof msg) != sizeof "done") {
 		fprintf(stderr, "Couldn't send/recv local address\n");
 		free(rem_dest);
 		rem_dest = NULL;
-- 
2.7.4

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