diff mbox series

stmmac: selftest: avoid large stack usage

Message ID 20190918195454.2056139-1-arnd@arndb.de
State Superseded
Headers show
Series stmmac: selftest: avoid large stack usage | expand

Commit Message

Arnd Bergmann Sept. 18, 2019, 7:54 p.m. UTC
Putting a struct stmmac_rss object on the stack is a bad idea,
as it exceeds the warning limit for a stack frame on 32-bit architectures:

drivers/net/ethernet/stmicro/stmmac/stmmac_selftests.c:1221:12: error: stack frame size of 1208 bytes in function '__stmmac_test_l3filt' [-Werror,-Wframe-larger-than=]
drivers/net/ethernet/stmicro/stmmac/stmmac_selftests.c:1338:12: error: stack frame size of 1208 bytes in function '__stmmac_test_l4filt' [-Werror,-Wframe-larger-than=]

As the object is the trivial empty case, change the called function
to accept a NULL pointer to mean the same thing and remove the
large variable in the two callers.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

---
 .../net/ethernet/stmicro/stmmac/dwxgmac2_core.c   | 15 +++++++++++----
 .../ethernet/stmicro/stmmac/stmmac_selftests.c    | 14 ++++----------
 2 files changed, 15 insertions(+), 14 deletions(-)

-- 
2.20.0

Comments

Jose Abreu Sept. 19, 2019, 7:58 a.m. UTC | #1
From: Arnd Bergmann <arnd@arndb.de>

Date: Sep/18/2019, 20:54:34 (UTC+00:00)

> +	if (!cfg || !cfg->enable) {

>  		value &= ~XGMAC_RSSE;

>  		writel(value, ioaddr + XGMAC_RSS_CTRL);

>  		return 0;

>  	}

>  

>  	for (i = 0; i < (sizeof(cfg->key) / sizeof(u32)); i++) {

> -		ret = dwxgmac2_rss_write_reg(ioaddr, true, i, *key++);

> +		if (cfg)

> +			ret = dwxgmac2_rss_write_reg(ioaddr, true, i, cfg->key[i]);

> +		else

> +			ret = dwxgmac2_rss_write_reg(ioaddr, true, i, 0);

> +

>  		if (ret)

>  			return ret;

>  	}

>  

>  	for (i = 0; i < ARRAY_SIZE(cfg->table); i++) {

> -		ret = dwxgmac2_rss_write_reg(ioaddr, false, i, cfg->table[i]);

> +		if (cfg)

> +			ret = dwxgmac2_rss_write_reg(ioaddr, false, i, cfg->table[i]);

> +		else

> +			ret = dwxgmac2_rss_write_reg(ioaddr, false, i, 0);

> +


I don't get these "if (cfg)" checks. You already check earlier if cfg is 
NULL and return if so. I don't think you need these extra checks.

Also, your subject line should be something like: "net: stmmac: 
selftests: ..."

---
Thanks,
Jose Miguel Abreu
Arnd Bergmann Sept. 19, 2019, 12:34 p.m. UTC | #2
On Thu, Sep 19, 2019 at 9:58 AM Jose Abreu <Jose.Abreu@synopsys.com> wrote:
>

> From: Arnd Bergmann <arnd@arndb.de>

> Date: Sep/18/2019, 20:54:34 (UTC+00:00)

>

> > +     if (!cfg || !cfg->enable) {

> >               value &= ~XGMAC_RSSE;

> >               writel(value, ioaddr + XGMAC_RSS_CTRL);

> >               return 0;

> >       }

> >

> >       for (i = 0; i < (sizeof(cfg->key) / sizeof(u32)); i++) {

> > -             ret = dwxgmac2_rss_write_reg(ioaddr, true, i, *key++);

> > +             if (cfg)

> > +                     ret = dwxgmac2_rss_write_reg(ioaddr, true, i, cfg->key[i]);

> > +             else

> > +                     ret = dwxgmac2_rss_write_reg(ioaddr, true, i, 0);

> > +

> >               if (ret)

> >                       return ret;

> >       }

> >

> >       for (i = 0; i < ARRAY_SIZE(cfg->table); i++) {

> > -             ret = dwxgmac2_rss_write_reg(ioaddr, false, i, cfg->table[i]);

> > +             if (cfg)

> > +                     ret = dwxgmac2_rss_write_reg(ioaddr, false, i, cfg->table[i]);

> > +             else

> > +                     ret = dwxgmac2_rss_write_reg(ioaddr, false, i, 0);

> > +

>

> I don't get these "if (cfg)" checks. You already check earlier if cfg is

> NULL and return if so. I don't think you need these extra checks.


Ah, you are right, I missed the 'return 0', that makes it much easier.

> Also, your subject line should be something like: "net: stmmac:

> selftests: ..."


I think both styles is common for network drivers, though I think most
just leave out the 'net:'. I changed it in v2 now.

      Arnd
diff mbox series

Patch

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
index d5173dd02a71..c2f648062049 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwxgmac2_core.c
@@ -523,25 +523,32 @@  static int dwxgmac2_rss_configure(struct mac_device_info *hw,
 				  struct stmmac_rss *cfg, u32 num_rxq)
 {
 	void __iomem *ioaddr = hw->pcsr;
-	u32 *key = (u32 *)cfg->key;
 	int i, ret;
 	u32 value;
 
 	value = readl(ioaddr + XGMAC_RSS_CTRL);
-	if (!cfg->enable) {
+	if (!cfg || !cfg->enable) {
 		value &= ~XGMAC_RSSE;
 		writel(value, ioaddr + XGMAC_RSS_CTRL);
 		return 0;
 	}
 
 	for (i = 0; i < (sizeof(cfg->key) / sizeof(u32)); i++) {
-		ret = dwxgmac2_rss_write_reg(ioaddr, true, i, *key++);
+		if (cfg)
+			ret = dwxgmac2_rss_write_reg(ioaddr, true, i, cfg->key[i]);
+		else
+			ret = dwxgmac2_rss_write_reg(ioaddr, true, i, 0);
+
 		if (ret)
 			return ret;
 	}
 
 	for (i = 0; i < ARRAY_SIZE(cfg->table); i++) {
-		ret = dwxgmac2_rss_write_reg(ioaddr, false, i, cfg->table[i]);
+		if (cfg)
+			ret = dwxgmac2_rss_write_reg(ioaddr, false, i, cfg->table[i]);
+		else
+			ret = dwxgmac2_rss_write_reg(ioaddr, false, i, 0);
+
 		if (ret)
 			return ret;
 	}
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_selftests.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_selftests.c
index c56e89e1ae56..9c8d210b2d6a 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_selftests.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_selftests.c
@@ -1233,12 +1233,9 @@  static int __stmmac_test_l3filt(struct stmmac_priv *priv, u32 dst, u32 src,
 		return -EOPNOTSUPP;
 	if (!priv->dma_cap.l3l4fnum)
 		return -EOPNOTSUPP;
-	if (priv->rss.enable) {
-		struct stmmac_rss rss = { .enable = false, };
-
-		stmmac_rss_configure(priv, priv->hw, &rss,
+	if (priv->rss.enable)
+		stmmac_rss_configure(priv, priv->hw, NULL,
 				     priv->plat->rx_queues_to_use);
-	}
 
 	dissector = kzalloc(sizeof(*dissector), GFP_KERNEL);
 	if (!dissector) {
@@ -1357,12 +1354,9 @@  static int __stmmac_test_l4filt(struct stmmac_priv *priv, u32 dst, u32 src,
 		return -EOPNOTSUPP;
 	if (!priv->dma_cap.l3l4fnum)
 		return -EOPNOTSUPP;
-	if (priv->rss.enable) {
-		struct stmmac_rss rss = { .enable = false, };
-
-		stmmac_rss_configure(priv, priv->hw, &rss,
+	if (priv->rss.enable)
+		stmmac_rss_configure(priv, priv->hw, NULL,
 				     priv->plat->rx_queues_to_use);
-	}
 
 	dissector = kzalloc(sizeof(*dissector), GFP_KERNEL);
 	if (!dissector) {