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From: Arnd Bergmann <arnd@arndb.de>
To: "David S. Miller" <davem@davemloft.net>
Cc: Arnd Bergmann <arnd@arndb.de>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Jakub Kicinski <jakub.kicinski@netronome.com>,
	Jiri Pirko <jiri@mellanox.com>, Wenwen Wang <wang6495@umn.edu>,
	Michal Kubecek <mkubecek@suse.cz>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] [v2] ethtool: reduce stack usage with clang
Date: Thu,  7 Mar 2019 16:58:35 +0100	[thread overview]
Message-ID: <20190307160017.3120362-1-arnd@arndb.de> (raw)

clang inlines the dev_ethtool() more aggressively than gcc does, leading
to a larger amount of used stack space:

net/core/ethtool.c:2536:24: error: stack frame size of 1216 bytes in function 'dev_ethtool' [-Werror,-Wframe-larger-than=]

Marking the sub-functions that require the most stack space as
noinline_for_stack gives us reasonable behavior on all compilers.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v2: don't annotate dev_ethtool itself, as pointed out by Michal Kubecek
---
 net/core/ethtool.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index d4918ffddda8..b1eb32419732 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -2319,9 +2319,10 @@ static int ethtool_set_tunable(struct net_device *dev, void __user *useraddr)
 	return ret;
 }
 
-static int ethtool_get_per_queue_coalesce(struct net_device *dev,
-					  void __user *useraddr,
-					  struct ethtool_per_queue_op *per_queue_opt)
+static noinline_for_stack int
+ethtool_get_per_queue_coalesce(struct net_device *dev,
+			       void __user *useraddr,
+			       struct ethtool_per_queue_op *per_queue_opt)
 {
 	u32 bit;
 	int ret;
@@ -2349,9 +2350,10 @@ static int ethtool_get_per_queue_coalesce(struct net_device *dev,
 	return 0;
 }
 
-static int ethtool_set_per_queue_coalesce(struct net_device *dev,
-					  void __user *useraddr,
-					  struct ethtool_per_queue_op *per_queue_opt)
+static noinline_for_stack int
+ethtool_set_per_queue_coalesce(struct net_device *dev,
+			       void __user *useraddr,
+			       struct ethtool_per_queue_op *per_queue_opt)
 {
 	u32 bit;
 	int i, ret = 0;
@@ -2405,7 +2407,7 @@ static int ethtool_set_per_queue_coalesce(struct net_device *dev,
 	return ret;
 }
 
-static int ethtool_set_per_queue(struct net_device *dev,
+static int noinline_for_stack ethtool_set_per_queue(struct net_device *dev,
 				 void __user *useraddr, u32 sub_cmd)
 {
 	struct ethtool_per_queue_op per_queue_opt;
-- 
2.20.0


             reply	other threads:[~2019-03-07 16:00 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-07 15:58 Arnd Bergmann [this message]
2019-03-07 16:41 ` [PATCH] [v2] ethtool: reduce stack usage with clang Michal Kubecek
2019-03-07 17:46 ` David Miller
2019-03-07 22:03   ` Arnd Bergmann

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