From a6e0b83bd5038f4d749e44e52d11cf24e0727089 Mon Sep 17 00:00:00 2001
From: Richard Cochran <richardcochran@gmail.com>
Date: Thu, 30 Apr 2020 06:13:33 -0700
Subject: [PATCH] sk: Convey transmit path errors to the caller.

The transport layer's functional interface foresees having error codes
percolate back up to the caller.  However, up until now, the sk module
simply returned -1 for any error.  This patch lets the code return the
specific error instead.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
---
 sk.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/sk.c b/sk.c
index e211175..c9ef4d2 100644
--- a/sk.c
+++ b/sk.c
@@ -354,7 +354,7 @@ int sk_receive(int fd, void *buf, int buflen,
 			             "timed out while polling for tx timestamp");
 			pr_err("increasing tx_timestamp_timeout may correct "
 			       "this issue, but it is likely caused by a driver bug");
-			return res;
+			return -errno;
 		} else if (!(pfd.revents & sk_revents)) {
 			pr_err("poll for tx timestamp woke up on non ERR event");
 			return -1;
@@ -362,24 +362,24 @@ int sk_receive(int fd, void *buf, int buflen,
 	}
 
 	cnt = recvmsg(fd, &msg, flags);
-	if (cnt < 0)
+	if (cnt < 0) {
 		pr_err("recvmsg%sfailed: %m",
 		       flags == MSG_ERRQUEUE ? " tx timestamp " : " ");
-
+	}
 	for (cm = CMSG_FIRSTHDR(&msg); cm != NULL; cm = CMSG_NXTHDR(&msg, cm)) {
 		level = cm->cmsg_level;
 		type  = cm->cmsg_type;
 		if (SOL_SOCKET == level && SO_TIMESTAMPING == type) {
 			if (cm->cmsg_len < sizeof(*ts) * 3) {
 				pr_warning("short SO_TIMESTAMPING message");
-				return -1;
+				return -EMSGSIZE;
 			}
 			ts = (struct timespec *) CMSG_DATA(cm);
 		}
 		if (SOL_SOCKET == level && SO_TIMESTAMPNS == type) {
 			if (cm->cmsg_len < sizeof(*sw)) {
 				pr_warning("short SO_TIMESTAMPNS message");
-				return -1;
+				return -EMSGSIZE;
 			}
 			sw = (struct timespec *) CMSG_DATA(cm);
 			hwts->sw = timespec_to_tmv(*sw);
@@ -391,7 +391,7 @@ int sk_receive(int fd, void *buf, int buflen,
 
 	if (!ts) {
 		memset(&hwts->ts, 0, sizeof(hwts->ts));
-		return cnt;
+		return cnt < 1 ? -errno : cnt;
 	}
 
 	switch (hwts->type) {
@@ -407,7 +407,7 @@ int sk_receive(int fd, void *buf, int buflen,
 		hwts->ts = timespec_to_tmv(ts[1]);
 		break;
 	}
-	return cnt;
+	return cnt < 1 ? -errno : cnt;
 }
 
 int sk_set_priority(int fd, int family, uint8_t dscp)