[PATCH 4.14 04/71] ethtool: reduce stack usage with clang

[Greg Kroah-Hartman]

From: Arnd Bergmann <arnd@xxxxxxxx>

commit 3499e87ea0413ee5b2cc028f4c8ed4d424bc7f98 upstream.

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@xxxxxxxx>
Reviewed-by: Michal Kubecek <mkubecek@xxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Miles Chen <miles.chen@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 net/core/ethtool.c |   16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -2343,9 +2343,10 @@ static int ethtool_set_tunable(struct ne
 	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;
@@ -2375,9 +2376,10 @@ static int ethtool_get_per_queue_coalesc
 	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;
@@ -2434,7 +2436,7 @@ roll_back:
 	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;