Hello All, LKML Post: http://kerneltrap.org/mailarchive/linux-kernel/2010/7/12/4592938 This proposal will provide the ability to shoot an 'ioctl' via an 'ethX' agnostic naming scheme. Requirement: R1)Ability to address NICs/interfaces using a mac-addr in ioctls. This is required because we don't have a consistent naming scheme for Ethernet devices. Asking customers and/or field-engineers to change udev rules and other config files is not feasible. Existing pain-points: P1) ioctl needs either i) if-name or ii) if-index before we can invoke bind() etc. This works fine if you know your configuration and it is not going to change. However,if we hot-add a NIC and if you have adapters from multiple vendors(think:driver load order) then upon a reboot, the 'eth' interfaces can be re-mapped. Existing work-around(s): W1) user-apps scan /sys/class/net/ethX/address nodes, grep the hw-addrs till they find a hwaddr-match and then internally create a hwaddr-ethX mapping table. W2) change udev-70..persistent rules file and 'rename' the interfaces according to your needs. W2.1) If renaming were to even succeed then none of the existing drivers re-register their msix-vectors. NETDEV_RENAME(or _CHANGE ) handler in the driver does not tear down the interrupts etc. Some of the sample msix-vectors are as follows : ethX-rx-0, ethX-rx-1 ... ethX-rx-N So if the interface is renamed then how do we measure/correlate the interrupt-count? But there is no programmatic way of deriving the 'ethX' name. I got a few offline replies to the above post, asking me to continue using W1) from above. Sorry but that was an ugly hack. Also why not replace the get-ioctls to a 'sys' read everywhere?? ;). Solution/Proposal: S1) Introduce a new ioctl(SIOCGHWADDR_TO_IFNAMEINDEX_MAP[or pick your name]) S1.1) Enhance dev_ioctl to handle this new case. S1.2 Re-use for_each_netdev_rcu::is_etherdev_addr(this will iterate through dev_addrs). By using the above for_each loop we don't need to re-invent the wheel. Input(ifr->hw_addr) : output -> if_name and if_index if ifr->hw_addr is found. This way an app can first shoot down an ioctl(sock_fd, SIOCGHWADDR_TO_IFNAMEINDEX_MAP,ifr), where ifr.ifr_hwaddr is populated w/ the mac_addr whose mapping you would like. Then once the if_name and if_index is known, using other ioctls is easy. Please review the proposal and the sample code below. If this is not a good approach and if there is a simple workaround then please let me know. Regards Chetan Loke ---------------------------------------------------------- Sample code(PS- I used a quick and dirty driver to demonstrate the concept rather than modifying the kernel) Copyright NetScout Systems Chetan Loke <loke.c@xxxxxxxxxxxxxx> struct foo { char name[IFNAMSIZ]; int index; }; /* shamelessly copied from compare_etherdev */ /* eventually is_etherdev_equal will be called by dev_ioctl */ int ntct_is_etherdev_equal(u16 *a,u16 *b) { return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | (a[2] ^ b[2])) == 0; } /* eventually enhance dev_ioctl */ int _do_ioctl(unsigned long arg) { struct foo my_foo; struct net_device *dev; int ret=0; int found=0; int i=0; /* eventually sent via ioctl(sock_fd)->SIOCG_HWADDR_TO_NAMEIDX_MAP and ifr->hw_addr */ unsigned char mac_addr[]={0x00,0x50,0x56,0xBB,0x52,0xF7}; /* eventually use rcu_read_lock(); */ read_lock(&dev_base_lock); /* 2.6.31 doesn't have this defined. eventually use for_each_netdev_rcu. */ for_each_netdev(&init_net, dev) { dev_hold(dev); /* eventually use is_etherdev_addr(addr1,addr2) */ ret = ntct_is_etherdev_equal((u16 *)dev->dev_addr,(u16 *)mac_addr); if (ret) { printk("<%s> Found eth-if:%s ifindex:%d\n",__func__,dev->name,dev->ifindex); printk("Mac:"); for (i=0;i<ETH_ALEN;i++) printk("%02x%c",(unsigned char)dev->dev_addr[i],((i < 5)? ':':' ')); printk("\n"); strcpy(my_foo.name,dev->name); my_foo.index=dev->ifindex; dev_put(dev); found=1; break; } dev_put(dev); } /* eventually use rcu_read_unlock(); */ read_unlock(&dev_base_lock); if (!found) { printk("<%s> hwaddr<->name mapping not found\n",__func__); return -EINVAL; } return copy_to_user((char *)arg,&my_foo,sizeof(struct foo)) ? -EFAULT : 0; } -- To unsubscribe from this list: send the line "unsubscribe linux-net" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
