[PATCH 4.9 04/97] ethtool: reduce stack usage with clang

Greg Kroah-Hartman
2020-01-22T09:33:57Z

From: Arnd Bergmann <arnd@arndb.de>

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@arndb.de>
Reviewed-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Miles Chen <miles.chen@mediatek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -2332,9 +2332,10 @@ out:
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;
@@ -2364,9 +2365,10 @@ 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;
@@ -2423,7 +2425,7 @@ 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;