On 03/13/2012 03:52 PM, Robert Love wrote: > The rtnl_mutex was held to protect calls to dev_uc_add > and dev_uc_del. Holding rtnl is not required as those > functions make use of the netif_addr_lock* API to > protect the MAC changing. > > This change fixes the following regression by removing > the rtnl usage when fcoe_update_src_mac is called. > > https://bugzilla.kernel.org/show_bug.cgi?id=42918 > > the existing dependency chain (in reverse order) is: > > -> #1 (&fip->ctlr_mutex){+.+...}: > [<c1091f70>] lock_acquire+0x80/0x1b0 > [<c147655d>] mutex_lock_nested+0x6d/0x340 > [<f8970c32>] fcoe_ctlr_link_up+0x22/0x180 [libfcoe] > [<f894620e>] fcoe_create+0x47e/0x6e0 [fcoe] > [<f8973dd3>] fcoe_transport_create+0x143/0x250 [libfcoe] > [<c10527e0>] param_attr_store+0x30/0x60 > [<c1052696>] module_attr_store+0x26/0x40 > [<c11a201e>] sysfs_write_file+0xae/0x100 > [<c11449df>] vfs_write+0x8f/0x160 > [<c1144cbd>] sys_write+0x3d/0x70 > [<c147a0c4>] syscall_call+0x7/0xb > > -> #0 (rtnl_mutex){+.+.+.}: > [<c109164b>] __lock_acquire+0x140b/0x1720 > [<c1091f70>] lock_acquire+0x80/0x1b0 > [<c147655d>] mutex_lock_nested+0x6d/0x340 > [<c13a10c4>] rtnl_lock+0x14/0x20 > [<f89445ac>] fcoe_update_src_mac+0x2c/0xb0 [fcoe] > [<f8971712>] fcoe_ctlr_timer_work+0x712/0xb60 [libfcoe] > [<c104fb69>] process_one_work+0x179/0x5d0 > [<c10502f1>] worker_thread+0x121/0x2d0 > [<c10550ed>] kthread+0x7d/0x90 > [<c1481a82>] kernel_thread_helper+0x6/0x10 > > other info that might help us debug this: > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > lock(&fip->ctlr_mutex); > lock(rtnl_mutex); > lock(&fip->ctlr_mutex); > lock(rtnl_mutex); > > *** DEADLOCK *** > > Signed-off-by: Robert Love<robert.w.love@xxxxxxxxx> > --- > drivers/scsi/fcoe/fcoe.c | 2 -- > 1 files changed, 0 insertions(+), 2 deletions(-) > > diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c > index e959960..85b8203 100644 > --- a/drivers/scsi/fcoe/fcoe.c > +++ b/drivers/scsi/fcoe/fcoe.c > @@ -539,13 +539,11 @@ static void fcoe_update_src_mac(struct fc_lport *lport, u8 *addr) > struct fcoe_port *port = lport_priv(lport); > struct fcoe_interface *fcoe = port->priv; > > - rtnl_lock(); > if (!is_zero_ether_addr(port->data_src_addr)) > dev_uc_del(fcoe->netdev, port->data_src_addr); > if (!is_zero_ether_addr(addr)) > dev_uc_add(fcoe->netdev, addr); > memcpy(port->data_src_addr, addr, ETH_ALEN); > - rtnl_unlock(); > } > > /** > This isn't going to work. We do need rtnl_lock when calling dev_uc_add/del to ensure the driver isn't removed while making the change. I have an alternative patch that I'll post as soon as I clean it up a bit. Nacked-by: Robert Love <robert.w.love@xxxxxxxxx>��.n��������+%������w��{.n�����{������ܨ}���Ơz�j:+v�����w����ޙ��&�)ߡ�a����z�ޗ���ݢj��w�f
