linux-kernel - [PATCH net-next v2] net: Remove redundant variable declaration in __dev_change

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Message-Id: <20250217-old_flags-v2-1-4cda3b43a35f@debian.org>
Date: Mon, 17 Feb 2025 07:48:13 -0800
From: Breno Leitao <leitao@...ian.org>
To: "David S. Miller" <davem@...emloft.net>, 
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, 
 Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, 
 Nicolas Dichtel <nicolas.dichtel@...nd.com>, andrew@...n.ch
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Breno Leitao <leitao@...ian.org>, 
 Mateusz Polchlopek <mateusz.polchlopek@...el.com>
Subject: [PATCH net-next v2] net: Remove redundant variable declaration in
 __dev_change_flags()

The old_flags variable is declared twice in __dev_change_flags(),
causing a shadow variable warning. This patch fixes the issue by
removing the redundant declaration, reusing the existing old_flags
variable instead.

	net/core/dev.c:9225:16: warning: declaration shadows a local variable [-Wshadow]
	9225 |                 unsigned int old_flags = dev->flags;
	|                              ^
	net/core/dev.c:9185:15: note: previous declaration is here
	9185 |         unsigned int old_flags = dev->flags;
	|                      ^
	1 warning generated.

Remove the redundant inner declaration and reuse the existing old_flags
variable since its value is not needed outside the if block, and it is
safe to reuse the variable. This eliminates the warning while
maintaining the same functionality.

Signed-off-by: Breno Leitao <leitao@...ian.org>
Reviewed-by: Mateusz Polchlopek <mateusz.polchlopek@...el.com>
---
Changes in v2:
- Improve the commit message to specify that there is no impact reusing
  the variable (Andrew)
- Remove the Fixes tag, since we do not want this to be backported.
  (Andrew)
- Link to v1: https://lore.kernel.org/r/20250214-old_flags-v1-1-29096b9399a9@debian.org
---
 net/core/dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index d5ab9a4b318ea4926c200ef20dae01eaafa18c6b..cd2474a138201e6ee86acf39ca425d57d8d2e9b4 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -9182,7 +9182,7 @@ int __dev_change_flags(struct net_device *dev, unsigned int flags,

 	if ((flags ^ dev->gflags) & IFF_PROMISC) {
 		int inc = (flags & IFF_PROMISC) ? 1 : -1;
-		unsigned int old_flags = dev->flags;
+		old_flags = dev->flags;

 		dev->gflags ^= IFF_PROMISC;

---
base-commit: 7a7e0197133d18cfd9931e7d3a842d0f5730223f
change-id: 20250214-old_flags-528fe052471c

Best regards,
-- 
Breno Leitao <leitao@...ian.org>