Message ID | 20090326100856.265f7872@nehalam |
---|---|
State | Accepted, archived |
Delegated to: | David Miller |
Headers | show |
On Fri, Mar 27, 2009 at 1:08 AM, Stephen Hemminger <shemminger@vyatta.com> wrote: > The code that was added to increase headroom was wrong. > It doesn't handle the case where gfar_add_fcb() changes the skb. Oops. I messed up the pointer to pointer manipulating. > Better to do check at start of transmit (outside of lock), where > error handling is better anyway. > > Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> > > > --- a/drivers/net/gianfar.c 2009-03-26 09:14:39.273669929 -0700 > +++ b/drivers/net/gianfar.c 2009-03-26 09:22:46.477545004 -0700 > @@ -1239,19 +1239,9 @@ static int gfar_enet_open(struct net_dev > return err; > } > > -static inline struct txfcb *gfar_add_fcb(struct sk_buff **skbp) > +static inline struct txfcb *gfar_add_fcb(struct sk_buff *skb) > { > - struct txfcb *fcb; > - struct sk_buff *skb = *skbp; > - > - if (unlikely(skb_headroom(skb) < GMAC_FCB_LEN)) { > - struct sk_buff *old_skb = skb; > - skb = skb_realloc_headroom(old_skb, GMAC_FCB_LEN); > - if (!skb) > - return NULL; > - dev_kfree_skb_any(old_skb); > - } > - fcb = (struct txfcb *)skb_push(skb, GMAC_FCB_LEN); > + struct txfcb *fcb = (struct txfcb *)skb_push(skb, GMAC_FCB_LEN); > cacheable_memzero(fcb, GMAC_FCB_LEN); > > return fcb; > @@ -1320,6 +1310,20 @@ static int gfar_start_xmit(struct sk_buf > > base = priv->tx_bd_base; > > + /* make space for additional header */ > + if (skb_headroom(skb) < GMAC_FCB_LEN) { > + struct sk_buff *skb_new; > + > + skb_new = skb_realloc_headroom(skb, GMAC_FCB_LEN); > + if (!skb_new) { > + dev->stats.tx_errors++; > + kfree(skb); > + return NETDEV_TX_OK; > + } > + kfree_skb(skb); > + skb = skb_new; > + } > + We have legacy devices without the offloading feature. And we can even turn off the IP checksum offloading at runtime. Your code will cause unnecessary realloc for these cases. I can propose a new patch to fix the pointer problem and add more error handling. > /* total number of fragments in the SKB */ > nr_frags = skb_shinfo(skb)->nr_frags; > > @@ -1372,20 +1376,18 @@ static int gfar_start_xmit(struct sk_buf > > /* Set up checksumming */ > if (CHECKSUM_PARTIAL == skb->ip_summed) { > - fcb = gfar_add_fcb(&skb); > - if (likely(fcb != NULL)) { > - lstatus |= BD_LFLAG(TXBD_TOE); > - gfar_tx_checksum(skb, fcb); > - } > + fcb = gfar_add_fcb(skb); > + lstatus |= BD_LFLAG(TXBD_TOE); > + gfar_tx_checksum(skb, fcb); > } > > if (priv->vlgrp && vlan_tx_tag_present(skb)) { > - if (unlikely(NULL == fcb)) > - fcb = gfar_add_fcb(&skb); > - if (likely(fcb != NULL)) { > + if (unlikely(NULL == fcb)) { > + fcb = gfar_add_fcb(skb); > lstatus |= BD_LFLAG(TXBD_TOE); > - gfar_tx_vlan(skb, fcb); > } > + > + gfar_tx_vlan(skb, fcb); > } > > /* setup the TxBD length and buffer pointer for the first BD */ > @@ -1433,7 +1435,7 @@ static int gfar_start_xmit(struct sk_buf > /* Unlock priv */ > spin_unlock_irqrestore(&priv->txlock, flags); > > - return 0; > + return NETDEV_TX_OK; > } > > /* Stops the kernel queue, and halts the controller */ -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Stephen Hemminger <shemminger@vyatta.com> Date: Thu, 26 Mar 2009 10:08:56 -0700 > The code that was added to increase headroom was wrong. > It doesn't handle the case where gfar_add_fcb() changes the skb. > Better to do check at start of transmit (outside of lock), where > error handling is better anyway. > > Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> Applied, thanks Stephen. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Li Yang <leoli@freescale.com> Date: Fri, 27 Mar 2009 12:26:33 +0800 > We have legacy devices without the offloading feature. And we can > even turn off the IP checksum offloading at runtime. Your code will > cause unnecessary realloc for these cases. > > I can propose a new patch to fix the pointer problem and add more > error handling. I'm applying Stephen's patch for now, please send any improvements relative to that. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, Mar 27, 2009 at 3:39 PM, David Miller <davem@davemloft.net> wrote: > From: Li Yang <leoli@freescale.com> > Date: Fri, 27 Mar 2009 12:26:33 +0800 > >> We have legacy devices without the offloading feature. And we can >> even turn off the IP checksum offloading at runtime. Your code will >> cause unnecessary realloc for these cases. >> >> I can propose a new patch to fix the pointer problem and add more >> error handling. > > I'm applying Stephen's patch for now, please send any improvements > relative to that. Ok. However is it ok to use kfree() instead of kfree_skb() in Stephen's patch? + skb_new = skb_realloc_headroom(skb, GMAC_FCB_LEN); + if (!skb_new) { + dev->stats.tx_errors++; + kfree(skb); + return NETDEV_TX_OK; + } - Leo -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
From: Li Yang <leoli@freescale.com> Date: Fri, 27 Mar 2009 16:06:27 +0800 > On Fri, Mar 27, 2009 at 3:39 PM, David Miller <davem@davemloft.net> wrote: > > From: Li Yang <leoli@freescale.com> > > Date: Fri, 27 Mar 2009 12:26:33 +0800 > > > >> We have legacy devices without the offloading feature. And we can > >> even turn off the IP checksum offloading at runtime. Your code will > >> cause unnecessary realloc for these cases. > >> > >> I can propose a new patch to fix the pointer problem and add more > >> error handling. > > > > I'm applying Stephen's patch for now, please send any improvements > > relative to that. > > Ok. > > However is it ok to use kfree() instead of kfree_skb() in Stephen's patch? > > + skb_new = skb_realloc_headroom(skb, GMAC_FCB_LEN); > + if (!skb_new) { > + dev->stats.tx_errors++; > + kfree(skb); > + return NETDEV_TX_OK; > + } I'll fix this, thanks for noticing. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
--- a/drivers/net/gianfar.c 2009-03-26 09:14:39.273669929 -0700 +++ b/drivers/net/gianfar.c 2009-03-26 09:22:46.477545004 -0700 @@ -1239,19 +1239,9 @@ static int gfar_enet_open(struct net_dev return err; } -static inline struct txfcb *gfar_add_fcb(struct sk_buff **skbp) +static inline struct txfcb *gfar_add_fcb(struct sk_buff *skb) { - struct txfcb *fcb; - struct sk_buff *skb = *skbp; - - if (unlikely(skb_headroom(skb) < GMAC_FCB_LEN)) { - struct sk_buff *old_skb = skb; - skb = skb_realloc_headroom(old_skb, GMAC_FCB_LEN); - if (!skb) - return NULL; - dev_kfree_skb_any(old_skb); - } - fcb = (struct txfcb *)skb_push(skb, GMAC_FCB_LEN); + struct txfcb *fcb = (struct txfcb *)skb_push(skb, GMAC_FCB_LEN); cacheable_memzero(fcb, GMAC_FCB_LEN); return fcb; @@ -1320,6 +1310,20 @@ static int gfar_start_xmit(struct sk_buf base = priv->tx_bd_base; + /* make space for additional header */ + if (skb_headroom(skb) < GMAC_FCB_LEN) { + struct sk_buff *skb_new; + + skb_new = skb_realloc_headroom(skb, GMAC_FCB_LEN); + if (!skb_new) { + dev->stats.tx_errors++; + kfree(skb); + return NETDEV_TX_OK; + } + kfree_skb(skb); + skb = skb_new; + } + /* total number of fragments in the SKB */ nr_frags = skb_shinfo(skb)->nr_frags; @@ -1372,20 +1376,18 @@ static int gfar_start_xmit(struct sk_buf /* Set up checksumming */ if (CHECKSUM_PARTIAL == skb->ip_summed) { - fcb = gfar_add_fcb(&skb); - if (likely(fcb != NULL)) { - lstatus |= BD_LFLAG(TXBD_TOE); - gfar_tx_checksum(skb, fcb); - } + fcb = gfar_add_fcb(skb); + lstatus |= BD_LFLAG(TXBD_TOE); + gfar_tx_checksum(skb, fcb); } if (priv->vlgrp && vlan_tx_tag_present(skb)) { - if (unlikely(NULL == fcb)) - fcb = gfar_add_fcb(&skb); - if (likely(fcb != NULL)) { + if (unlikely(NULL == fcb)) { + fcb = gfar_add_fcb(skb); lstatus |= BD_LFLAG(TXBD_TOE); - gfar_tx_vlan(skb, fcb); } + + gfar_tx_vlan(skb, fcb); } /* setup the TxBD length and buffer pointer for the first BD */ @@ -1433,7 +1435,7 @@ static int gfar_start_xmit(struct sk_buf /* Unlock priv */ spin_unlock_irqrestore(&priv->txlock, flags); - return 0; + return NETDEV_TX_OK; } /* Stops the kernel queue, and halts the controller */
The code that was added to increase headroom was wrong. It doesn't handle the case where gfar_add_fcb() changes the skb. Better to do check at start of transmit (outside of lock), where error handling is better anyway. Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html