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authorTobias Diedrich <ranma+kernel@tdiedrich.de>2008-07-03 23:54:56 -0700
committerJeff Garzik <jgarzik@redhat.com>2008-07-04 08:09:52 -0400
commit97bff0953dd45a633fa69e1a650d612f5610a60b (patch)
treebbc0ec1a2775ee12a412bad9feb0146a3ff1833d
parent54364b752ef0c91fe92684df000cc4593d1e8963 (diff)
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forcedeth: fix lockdep warning on ethtool -s
After enabling CONFIG_LOCKDEP and CONFIG_PROVE_LOCKING I get the following warning when ethtool -s is first called on one of the forcedeth ports: ================================= [ INFO: inconsistent lock state ] 2.6.26-rc4 #28 --------------------------------- inconsistent {in-hardirq-W} -> {hardirq-on-W} usage. ethtool/1985 [HC0[0]:SC0[1]:HE1:SE0] takes: (&np->lock){++..}, at: [<ffffffffa000c5fd>] nv_set_settings+0xc8/0x3de [forcedeth] {in-hardirq-W} state was registered at: [<ffffffffffffffff>] 0xffffffffffffffff irq event stamp: 3606 hardirqs last enabled at (3605): [<ffffffff8068106f>] _spin_unlock_irqrestore+0x3f/0x68 hardirqs last disabled at (3604): [<ffffffff80680d38>] _spin_lock_irqsave+0x13/0x46 softirqs last enabled at (3534): [<ffffffff80246ba5>] __do_softirq+0xbc/0xc5 softirqs last disabled at (3606): [<ffffffff80680b33>] _spin_lock_bh+0x11/0x41 other info that might help us debug this: 2 locks held by ethtool/1985: #0: (rtnl_mutex){--..}, at: [<ffffffff80596072>] rtnl_lock+0x12/0x14 #1: (_xmit_ETHER){-+..}, at: [<ffffffffa000c5e8>] nv_set_settings+0xb3/0x3de [forcedeth] stack backtrace: Pid: 1985, comm: ethtool Not tainted 2.6.26-rc4 #28 Call Trace: [<ffffffff8025f190>] print_usage_bug+0x162/0x173 [<ffffffff8025fa8b>] mark_lock+0x231/0x41f [<ffffffff802607cf>] __lock_acquire+0x4e7/0xcac [<ffffffff8025fe64>] ? trace_hardirqs_on+0xf1/0x115 [<ffffffff80272c3a>] ? disable_irq_nosync+0x6f/0x7b [<ffffffff80261375>] lock_acquire+0x55/0x6e [<ffffffffa000c5fd>] ? :forcedeth:nv_set_settings+0xc8/0x3de [<ffffffff80680b15>] _spin_lock+0x2f/0x3c [<ffffffffa000c5fd>] :forcedeth:nv_set_settings+0xc8/0x3de [<ffffffff8058f8bb>] dev_ethtool+0x186/0xea3 [<ffffffff8067f446>] ? mutex_lock_nested+0x243/0x275 [<ffffffff8025df2b>] ? debug_mutex_free_waiter+0x46/0x4a [<ffffffff8067f469>] ? mutex_lock_nested+0x266/0x275 [<ffffffff8058e1ce>] dev_ioctl+0x4eb/0x600 [<ffffffff8068106f>] ? _spin_unlock_irqrestore+0x3f/0x68 [<ffffffff80580f91>] sock_ioctl+0x1f5/0x202 [<ffffffff802a322e>] vfs_ioctl+0x2a/0x77 [<ffffffff802a34d6>] do_vfs_ioctl+0x25b/0x270 [<ffffffff806807b6>] ? trace_hardirqs_on_thunk+0x35/0x3a [<ffffffff802a352d>] sys_ioctl+0x42/0x65 [<ffffffff8021fffb>] system_call_after_swapgs+0x7b/0x80 This is caused by the following snippet in nv_set_settings: netif_carrier_off(dev); if (netif_running(dev)) { nv_disable_irq(dev); netif_tx_lock_bh(dev); spin_lock(&np->lock); /* stop engines */ nv_stop_rxtx(dev); spin_unlock(&np->lock); netif_tx_unlock_bh(dev); } Because of nv_disable_irq this is probably not really a problem though (I guess) and replacing the spin_lock with spin_lock_irqsave could keep interrupts disabled for a longer period of time because of delays in nv_stop_rx and nv_stop_tx. Signed-off-by: Tobias Diedrich <ranma+kernel@tdiedrich.de> Cc: Ayaz Abdulla <aabdulla@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
-rw-r--r--drivers/net/forcedeth.c15
1 files changed, 13 insertions, 2 deletions
diff --git a/drivers/net/forcedeth.c b/drivers/net/forcedeth.c
index 2cb244763292..20d4fe96a81c 100644
--- a/drivers/net/forcedeth.c
+++ b/drivers/net/forcedeth.c
@@ -4194,12 +4194,23 @@ static int nv_set_settings(struct net_device *dev, struct ethtool_cmd *ecmd)
netif_carrier_off(dev);
if (netif_running(dev)) {
+ unsigned long flags;
+
nv_disable_irq(dev);
netif_tx_lock_bh(dev);
- spin_lock(&np->lock);
+ /* with plain spinlock lockdep complains */
+ spin_lock_irqsave(&np->lock, flags);
/* stop engines */
+ /* FIXME:
+ * this can take some time, and interrupts are disabled
+ * due to spin_lock_irqsave, but let's hope no daemon
+ * is going to change the settings very often...
+ * Worst case:
+ * NV_RXSTOP_DELAY1MAX + NV_TXSTOP_DELAY1MAX
+ * + some minor delays, which is up to a second approximately
+ */
nv_stop_rxtx(dev);
- spin_unlock(&np->lock);
+ spin_unlock_irqrestore(&np->lock, flags);
netif_tx_unlock_bh(dev);
}