diff mbox series

[net/next] net: ipconfig: Avoid spurious blank lines in boot log

Message ID 20201110073757.1284594-1-thierry.reding@gmail.com (mailing list archive)
State Accepted
Delegated to: Netdev Maintainers
Headers show
Series [net/next] net: ipconfig: Avoid spurious blank lines in boot log | expand

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netdev/cover_letter success Link
netdev/fixes_present fail Series targets non-next tree, but doesn't contain any Fixes tags
netdev/patch_count success Link
netdev/tree_selection success Clearly marked for net
netdev/subject_prefix success Link
netdev/source_inline success Was 0 now: 0
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netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 1 this patch: 1
netdev/kdoc success Errors and warnings before: 0 this patch: 0
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netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 43 lines checked
netdev/build_allmodconfig_warn success Errors and warnings before: 1 this patch: 1
netdev/header_inline success Link
netdev/stable success Stable not CCed

Commit Message

Thierry Reding Nov. 10, 2020, 7:37 a.m. UTC
From: Thierry Reding <treding@nvidia.com>

When dumping the name and NTP servers advertised by DHCP, a blank line
is emitted if either of the lists is empty. This can lead to confusing
issues such as the blank line getting flagged as warning. This happens
because the blank line is the result of pr_cont("\n") and that may see
its level corrupted by some other driver concurrently writing to the
console.

Fix this by making sure that the terminating newline is only emitted
if at least one entry in the lists was printed before.

Reported-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
---
 net/ipv4/ipconfig.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

Comments

Jakub Kicinski Nov. 12, 2020, 10:55 p.m. UTC | #1
On Tue, 10 Nov 2020 08:37:57 +0100 Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
> 
> When dumping the name and NTP servers advertised by DHCP, a blank line
> is emitted if either of the lists is empty. This can lead to confusing
> issues such as the blank line getting flagged as warning. This happens
> because the blank line is the result of pr_cont("\n") and that may see
> its level corrupted by some other driver concurrently writing to the
> console.
> 
> Fix this by making sure that the terminating newline is only emitted
> if at least one entry in the lists was printed before.
> 
> Reported-by: Jon Hunter <jonathanh@nvidia.com>
> Signed-off-by: Thierry Reding <treding@nvidia.com>

Applied, thanks!
diff mbox series

Patch

diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c
index 561f15b5a944..3cd13e1bc6a7 100644
--- a/net/ipv4/ipconfig.c
+++ b/net/ipv4/ipconfig.c
@@ -1441,7 +1441,7 @@  static int __init ip_auto_config(void)
 	int retries = CONF_OPEN_RETRIES;
 #endif
 	int err;
-	unsigned int i;
+	unsigned int i, count;
 
 	/* Initialise all name servers and NTP servers to NONE (but only if the
 	 * "ip=" or "nfsaddrs=" kernel command line parameters weren't decoded,
@@ -1575,7 +1575,7 @@  static int __init ip_auto_config(void)
 	if (ic_dev_mtu)
 		pr_cont(", mtu=%d", ic_dev_mtu);
 	/* Name servers (if any): */
-	for (i = 0; i < CONF_NAMESERVERS_MAX; i++) {
+	for (i = 0, count = 0; i < CONF_NAMESERVERS_MAX; i++) {
 		if (ic_nameservers[i] != NONE) {
 			if (i == 0)
 				pr_info("     nameserver%u=%pI4",
@@ -1583,12 +1583,14 @@  static int __init ip_auto_config(void)
 			else
 				pr_cont(", nameserver%u=%pI4",
 					i, &ic_nameservers[i]);
+
+			count++;
 		}
-		if (i + 1 == CONF_NAMESERVERS_MAX)
+		if ((i + 1 == CONF_NAMESERVERS_MAX) && count > 0)
 			pr_cont("\n");
 	}
 	/* NTP servers (if any): */
-	for (i = 0; i < CONF_NTP_SERVERS_MAX; i++) {
+	for (i = 0, count = 0; i < CONF_NTP_SERVERS_MAX; i++) {
 		if (ic_ntp_servers[i] != NONE) {
 			if (i == 0)
 				pr_info("     ntpserver%u=%pI4",
@@ -1596,8 +1598,10 @@  static int __init ip_auto_config(void)
 			else
 				pr_cont(", ntpserver%u=%pI4",
 					i, &ic_ntp_servers[i]);
+
+			count++;
 		}
-		if (i + 1 == CONF_NTP_SERVERS_MAX)
+		if ((i + 1 == CONF_NTP_SERVERS_MAX) && count > 0)
 			pr_cont("\n");
 	}
 #endif /* !SILENT */