From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.tranzeo.com (mail.tranzeo.com [64.114.87.10]) by ozlabs.org (Postfix) with ESMTP id A7CADDE3C2 for ; Sat, 16 Aug 2008 03:03:07 +1000 (EST) Subject: Possible init bug in ibm_newemac/core.c From: Darcy Watkins To: linuxppc-embedded Content-Type: text/plain Date: Fri, 15 Aug 2008 10:03:05 -0700 Message-Id: <1218819785.3465.190.camel@localhost> Mime-Version: 1.0 List-Id: Linux on Embedded PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hello, In function... static int __devinit emac_probe(struct of_device *ofdev, const struct of_device_id *match) ... in drivers/net/ibm_newemac/core.c ... there is a chunk of code as follows (The // DLW - BUG ... comment is mine) ... /* Find PHY if any */ // DLW - BUG - This uses an uninitialized spinlock (potential badness). err = emac_init_phy(dev); if (err != 0) goto err_detach_tah; /* Fill in the driver function table */ ndev->open = &emac_open; if (dev->tah_dev) ndev->features |= NETIF_F_IP_CSUM | NETIF_F_SG; ndev->tx_timeout = &emac_tx_timeout; ndev->watchdog_timeo = 5 * HZ; ndev->stop = &emac_close; ndev->get_stats = &emac_stats; ndev->set_multicast_list = &emac_set_multicast_list; ndev->do_ioctl = &emac_ioctl; if (emac_phy_supports_gige(dev->phy_mode)) { ndev->hard_start_xmit = &emac_start_xmit_sg; ndev->change_mtu = &emac_change_mtu; dev->commac.ops = &emac_commac_sg_ops; } else { ndev->hard_start_xmit = &emac_start_xmit; } SET_ETHTOOL_OPS(ndev, &emac_ethtool_ops); netif_carrier_off(ndev); netif_stop_queue(ndev); err = register_netdev(ndev); if (err) { printk(KERN_ERR "%s: failed to register net device (%d)!\n", np->full_name, err); goto err_detach_tah; } init_emac_phy() uses a spinlock that isn't initialized until register_netdev() is invoked. I tried moving the init_emac_phy() to be after the register_netdev(). The fix appeared to work on one board variant (with two Ethernet ports) but kernel panics during boot on another board variant (with one Etherent port and less memory). So I have reverted my lame hack attempt and am reporting this so that an expert can check into it. The bug normally goes unnoticed until you turn on spinlock and/or rtmutex debuggging in the kernel config - then the debugging magic checks will catch it during boot. This is based on kernel 2.6.25.8-rt7 and then upgraded to be 2.6.25.13-rt7 using incremental patches - running on an AMCC PPC405EP but I think you could reproduce it using 2.6.25.8-rt7 (or possibly other kernel versions). -- Regards, Darcy -------------- Darcy L. Watkins - Senior Software Developer Tranzeo Wireless Technologies, Inc. 19273 Fraser Way, Pitt Meadows, BC, Canada V3Y 2V4 T:604-460-6002 ext:410 http://www.tranzeo.com