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 <[email protected]>
---
net/core/ethtool.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)
diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index d4918ffddda8..fcbed78172a0 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;
@@ -2533,7 +2535,7 @@ static int ethtool_set_fecparam(struct net_device *dev, void __user *useraddr)
/* The main entry point in this file. Called from net/core/dev_ioctl.c */
-int dev_ethtool(struct net *net, struct ifreq *ifr)
+int noinline_for_stack dev_ethtool(struct net *net, struct ifreq *ifr)
{
struct net_device *dev = __dev_get_by_name(net, ifr->ifr_name);
void __user *useraddr = ifr->ifr_data;
--
2.20.0
On Thu, Mar 07, 2019 at 10:33:35AM +0100, Arnd Bergmann wrote:
> 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 <[email protected]>
> ---
> net/core/ethtool.c | 18 ++++++++++--------
> 1 file changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/net/core/ethtool.c b/net/core/ethtool.c
> index d4918ffddda8..fcbed78172a0 100644
> --- a/net/core/ethtool.c
> +++ b/net/core/ethtool.c
...
> @@ -2533,7 +2535,7 @@ static int ethtool_set_fecparam(struct net_device *dev, void __user *useraddr)
>
> /* The main entry point in this file. Called from net/core/dev_ioctl.c */
>
> -int dev_ethtool(struct net *net, struct ifreq *ifr)
> +int noinline_for_stack dev_ethtool(struct net *net, struct ifreq *ifr)
> {
> struct net_device *dev = __dev_get_by_name(net, ifr->ifr_name);
> void __user *useraddr = ifr->ifr_data;
Is this part really needed? AFAICS dev_ethtool() is only called from
dev_ioctl() which is in a different compilation unit so that
dev_ethtool() won't be inlined anyway.
Michal Kubecek
On Thu, Mar 7, 2019 at 11:06 AM Michal Kubecek <[email protected]> wrote:
>
> On Thu, Mar 07, 2019 at 10:33:35AM +0100, Arnd Bergmann wrote:
> > @@ -2533,7 +2535,7 @@ static int ethtool_set_fecparam(struct net_device *dev, void __user *useraddr)
> >
> > /* The main entry point in this file. Called from net/core/dev_ioctl.c */
> >
> > -int dev_ethtool(struct net *net, struct ifreq *ifr)
> > +int noinline_for_stack dev_ethtool(struct net *net, struct ifreq *ifr)
> > {
> > struct net_device *dev = __dev_get_by_name(net, ifr->ifr_name);
> > void __user *useraddr = ifr->ifr_data;
>
> Is this part really needed? AFAICS dev_ethtool() is only called from
> dev_ioctl() which is in a different compilation unit so that
> dev_ethtool() won't be inlined anyway.
No, you are right. I had accidentally left this in place from an earlier
version. Sending a v2 now.
Arnd