Message-ID: <025d01c796ce$161e6ab0$0202fea9@Jura>
Date:	Tue, 15 May 2007 12:50:27 +0400
From:	"Yuriy N. Shkandybin" <jura@...ams.com>
To:	"Jarek Poplawski" <jarkao2@...pl>,
	"David Miller" <davem@...emloft.net>
Cc:	<akpm@...ux-foundation.org>, <jeff@...zik.org>,
	<netdev@...r.kernel.org>, <paulus@...ba.org>
Subject: Re: [PATCH] netdev: lockdep classes in register_netdevice Re: [patch 04/13] ppp_generic: fix lockdep warning

I've patched 2.6.22-rc1 and there was no warnings from lock debugger.

Jura

----- Original Message ----- 
From: "Jarek Poplawski" <jarkao2@...pl>
To: "David Miller" <davem@...emloft.net>
Cc: <akpm@...ux-foundation.org>; <jeff@...zik.org>; 
<netdev@...r.kernel.org>; <jura@...ams.com>; <paulus@...ba.org>
Sent: Tuesday, May 15, 2007 9:31 AM
Subject: [PATCH] netdev: lockdep classes in register_netdevice Re: [patch 
04/13] ppp_generic: fix lockdep warning


> On Sun, May 13, 2007 at 11:39:37PM -0700, David Miller wrote:
>> From: Jarek Poplawski <jarkao2@...pl>
>> Date: Mon, 14 May 2007 08:07:00 +0200
>>
>> > After sending this patch I was a little confused, when next
>> > lockdep warning report appeared, and I thought - since this is
>> > not enough, this patch could be dumped. But now I changed my
>> > mind: there are really many possibilities of strange connections
>> > between locks taken from vlans, ppp (with pppoe), multicasts etc.
>> > - that every one possibility less is a gain here.
>>  ...
>> > Of course, later, if somebody will find better solution, they could
>> > be removed,
>>
>> I already suggested a better fix, you ignored it.
>>
>> For each unique netdev type, use a different locking class.
>>
>> That will fix this forever, anything else is a situation specific
>> band-aid (but then again isn't that what every lockdep annotation is
>> :-).
>
> So, I guess, you thought about something like this, plus
> additional annotations in specific situations like vlan
> (but some hint is needed, how much of this should be
> considered).
>
> Jarek P.
>
> --->
>
> After initializing dev->_xmit_lock register_netdevice()
> sets lockdep class according to dev->type.
>
> Idea of this patch - by David Miller.
>
>
> Signed-off-by: Jarek Poplawski <jarkao2@...pl>
>
> ---
>
> diff -Nurp 2.6.22-/net/core/dev.c 2.6.22/net/core/dev.c
> --- 2.6.22-/net/core/dev.c 2007-05-14 20:26:16.000000000 +0200
> +++ 2.6.22/net/core/dev.c 2007-05-14 21:22:10.000000000 +0200
> @@ -116,6 +116,7 @@
> #include <linux/dmaengine.h>
> #include <linux/err.h>
> #include <linux/ctype.h>
> +#include <linux/if_arp.h>
>
> /*
>  * The list of packet types we will receive (as opposed to discard)
> @@ -217,6 +218,73 @@ extern void netdev_unregister_sysfs(stru
> #define netdev_unregister_sysfs(dev) do { } while(0)
> #endif
>
> +#ifdef CONFIG_DEBUG_LOCK_ALLOC
> +/*
> + * register_netdevice() inits dev->_xmit_lock and sets lockdep class
> + * according to dev->type
> + */
> +static const unsigned short netdev_lock_type[] =
> + {ARPHRD_NETROM, ARPHRD_ETHER, ARPHRD_EETHER, ARPHRD_AX25,
> + ARPHRD_PRONET, ARPHRD_CHAOS, ARPHRD_IEEE802, ARPHRD_ARCNET,
> + ARPHRD_APPLETLK, ARPHRD_DLCI, ARPHRD_ATM, ARPHRD_METRICOM,
> + ARPHRD_IEEE1394, ARPHRD_EUI64, ARPHRD_INFINIBAND, ARPHRD_SLIP,
> + ARPHRD_CSLIP, ARPHRD_SLIP6, ARPHRD_CSLIP6, ARPHRD_RSRVD,
> + ARPHRD_ADAPT, ARPHRD_ROSE, ARPHRD_X25, ARPHRD_HWX25,
> + ARPHRD_PPP, ARPHRD_CISCO, ARPHRD_LAPB, ARPHRD_DDCMP,
> + ARPHRD_RAWHDLC, ARPHRD_TUNNEL, ARPHRD_TUNNEL6, ARPHRD_FRAD,
> + ARPHRD_SKIP, ARPHRD_LOOPBACK, ARPHRD_LOCALTLK, ARPHRD_FDDI,
> + ARPHRD_BIF, ARPHRD_SIT, ARPHRD_IPDDP, ARPHRD_IPGRE,
> + ARPHRD_PIMREG, ARPHRD_HIPPI, ARPHRD_ASH, ARPHRD_ECONET,
> + ARPHRD_IRDA, ARPHRD_FCPP, ARPHRD_FCAL, ARPHRD_FCPL,
> + ARPHRD_FCFABRIC, ARPHRD_IEEE802_TR, ARPHRD_IEEE80211,
> + ARPHRD_IEEE80211_PRISM, ARPHRD_IEEE80211_RADIOTAP, ARPHRD_VOID,
> + ARPHRD_NONE};
> +
> +static const char *netdev_lock_name[] =
> + {"_xmit_NETROM", "_xmit_ETHER", "_xmit_EETHER", "_xmit_AX25",
> + "_xmit_PRONET", "_xmit_CHAOS", "_xmit_IEEE802", "_xmit_ARCNET",
> + "_xmit_APPLETLK", "_xmit_DLCI", "_xmit_ATM", "_xmit_METRICOM",
> + "_xmit_IEEE1394", "_xmit_EUI64", "_xmit_INFINIBAND", "_xmit_SLIP",
> + "_xmit_CSLIP", "_xmit_SLIP6", "_xmit_CSLIP6", "_xmit_RSRVD",
> + "_xmit_ADAPT", "_xmit_ROSE", "_xmit_X25", "_xmit_HWX25",
> + "_xmit_PPP", "_xmit_CISCO", "_xmit_LAPB", "_xmit_DDCMP",
> + "_xmit_RAWHDLC", "_xmit_TUNNEL", "_xmit_TUNNEL6", "_xmit_FRAD",
> + "_xmit_SKIP", "_xmit_LOOPBACK", "_xmit_LOCALTLK", "_xmit_FDDI",
> + "_xmit_BIF", "_xmit_SIT", "_xmit_IPDDP", "_xmit_IPGRE",
> + "_xmit_PIMREG", "_xmit_HIPPI", "_xmit_ASH", "_xmit_ECONET",
> + "_xmit_IRDA", "_xmit_FCPP", "_xmit_FCAL", "_xmit_FCPL",
> + "_xmit_FCFABRIC", "_xmit_IEEE802_TR", "_xmit_IEEE80211",
> + "_xmit_IEEE80211_PRISM", "_xmit_IEEE80211_RADIOTAP", "_xmit_VOID",
> + "_xmit_NONE"};
> +
> +static struct lock_class_key 
> netdev_xmit_lock_key[ARRAY_SIZE(netdev_lock_type)];
> +
> +static inline unsigned short netdev_lock_pos(unsigned short dev_type)
> +{
> + int i;
> +
> + for (i = 0; i < ARRAY_SIZE(netdev_lock_type); i++)
> + if (netdev_lock_type[i] == dev_type)
> + return i;
> + /* the last key is used by default */
> + return --i;
> +}
> +
> +static inline void netdev_set_lockdep_class(spinlock_t *lock,
> +     unsigned short dev_type)
> +{
> + int i;
> +
> + i = netdev_lock_pos(dev_type);
> + lockdep_set_class_and_name(lock, &netdev_xmit_lock_key[i],
> +    netdev_lock_name[i]);
> +}
> +#else
> +static inline void netdev_set_lockdep_class(spinlock_t *lock,
> +     unsigned short dev_type)
> +{
> +}
> +#endif
>
> /*******************************************************************************
>
> @@ -3001,6 +3069,7 @@ int register_netdevice(struct net_device
>
>  spin_lock_init(&dev->queue_lock);
>  spin_lock_init(&dev->_xmit_lock);
> + netdev_set_lockdep_class(&dev->_xmit_lock, dev->type);
>  dev->xmit_lock_owner = -1;
>  spin_lock_init(&dev->ingress_lock);
>
> 

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