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pkt_sched: Add lockdep annotation for qdisc locks 

Qdisc locks are initialized in the same function, qdisc_alloc(), so
lockdep can't distinguish tx qdisc lock from rx and reports "possible
recursive locking detected" when both these locks are taken eg. while
using act_mirred with ifb. This looks like a false positive. Anyway,
after this patch these locks will be reported more exactly.

Reported-by: Denys Fedoryshchenko <denys@visp.net.lb>
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jarek Poplawski 2008-08-18 20:53:34 -07:00 committed by David S. Miller
parent 8608db031b
commit 25bfcd5a78
1 changed files with 7 additions and 0 deletions
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7
net/sched/sch_api.c
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@ -27,6 +27,7 @@
#include <linux/kmod.h>
#include <linux/list.h>
#include <linux/hrtimer.h>
#include <linux/lockdep.h>
#include <net/net_namespace.h>
#include <net/sock.h>
@ -707,6 +708,10 @@ static int qdisc_graft(struct net_device *dev, struct Qdisc *parent,
return err;
}
/* lockdep annotation is needed for ingress; egress gets it only for name */
static struct lock_class_key qdisc_tx_lock;
static struct lock_class_key qdisc_rx_lock;
/*
Allocate and initialize new qdisc.
@ -767,6 +772,7 @@ qdisc_create(struct net_device *dev, struct netdev_queue *dev_queue,
if (handle == TC_H_INGRESS) {
sch->flags |= TCQ_F_INGRESS;
handle = TC_H_MAKE(TC_H_INGRESS, 0);
lockdep_set_class(qdisc_lock(sch), &qdisc_rx_lock);
} else {
if (handle == 0) {
handle = qdisc_alloc_handle(dev);
@ -774,6 +780,7 @@ qdisc_create(struct net_device *dev, struct netdev_queue *dev_queue,
if (handle == 0)
goto err_out3;
}
lockdep_set_class(qdisc_lock(sch), &qdisc_tx_lock);
}
sch->handle = handle;