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SubjectRe: Regression in 3.8-rc1: "BUG: sleeping function called from invalid context"
From
From: Borislav Petkov <bp@alien8.de>
Date: Sat, 22 Dec 2012 19:02:47 +0100

> Top-posting so that the rest can remain untouched.

This bug is fixed in the 'net' tree already by commit:

From 30e6c9fa93cf3dbc7cc6df1d748ad25e4264545a Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Thu, 20 Dec 2012 17:25:08 +0000
Subject: [PATCH 04/10] net: devnet_rename_seq should be a seqcount

Using a seqlock for devnet_rename_seq is not a good idea,
as device_rename() can sleep.

As we hold RTNL, we dont need a protection for writers,
and only need a seqcount so that readers can catch a change done
by a writer.

Bug added in commit c91f6df2db4972d3 (sockopt: Change getsockopt() of
SO_BINDTODEVICE to return an interface name)

Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Brian Haley <brian.haley@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
include/linux/netdevice.h | 2 +-
net/core/dev.c | 18 +++++++++---------
net/core/sock.c | 4 ++--
3 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 02e0f6b..c599e47 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1576,7 +1576,7 @@ extern int call_netdevice_notifiers(unsigned long val, struct net_device *dev);

extern rwlock_t dev_base_lock; /* Device list lock */

-extern seqlock_t devnet_rename_seq; /* Device rename lock */
+extern seqcount_t devnet_rename_seq; /* Device rename seq */


#define for_each_netdev(net, d) \
diff --git a/net/core/dev.c b/net/core/dev.c
index d0cbc93..515473e 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -203,7 +203,7 @@ static struct list_head offload_base __read_mostly;
DEFINE_RWLOCK(dev_base_lock);
EXPORT_SYMBOL(dev_base_lock);

-DEFINE_SEQLOCK(devnet_rename_seq);
+seqcount_t devnet_rename_seq;

static inline void dev_base_seq_inc(struct net *net)
{
@@ -1093,10 +1093,10 @@ int dev_change_name(struct net_device *dev, const char *newname)
if (dev->flags & IFF_UP)
return -EBUSY;

- write_seqlock(&devnet_rename_seq);
+ write_seqcount_begin(&devnet_rename_seq);

if (strncmp(newname, dev->name, IFNAMSIZ) == 0) {
- write_sequnlock(&devnet_rename_seq);
+ write_seqcount_end(&devnet_rename_seq);
return 0;
}

@@ -1104,7 +1104,7 @@ int dev_change_name(struct net_device *dev, const char *newname)

err = dev_get_valid_name(net, dev, newname);
if (err < 0) {
- write_sequnlock(&devnet_rename_seq);
+ write_seqcount_end(&devnet_rename_seq);
return err;
}

@@ -1112,11 +1112,11 @@ rollback:
ret = device_rename(&dev->dev, dev->name);
if (ret) {
memcpy(dev->name, oldname, IFNAMSIZ);
- write_sequnlock(&devnet_rename_seq);
+ write_seqcount_end(&devnet_rename_seq);
return ret;
}

- write_sequnlock(&devnet_rename_seq);
+ write_seqcount_end(&devnet_rename_seq);

write_lock_bh(&dev_base_lock);
hlist_del_rcu(&dev->name_hlist);
@@ -1135,7 +1135,7 @@ rollback:
/* err >= 0 after dev_alloc_name() or stores the first errno */
if (err >= 0) {
err = ret;
- write_seqlock(&devnet_rename_seq);
+ write_seqcount_begin(&devnet_rename_seq);
memcpy(dev->name, oldname, IFNAMSIZ);
goto rollback;
} else {
@@ -4180,7 +4180,7 @@ static int dev_ifname(struct net *net, struct ifreq __user *arg)
return -EFAULT;

retry:
- seq = read_seqbegin(&devnet_rename_seq);
+ seq = read_seqcount_begin(&devnet_rename_seq);
rcu_read_lock();
dev = dev_get_by_index_rcu(net, ifr.ifr_ifindex);
if (!dev) {
@@ -4190,7 +4190,7 @@ retry:

strcpy(ifr.ifr_name, dev->name);
rcu_read_unlock();
- if (read_seqretry(&devnet_rename_seq, seq))
+ if (read_seqcount_retry(&devnet_rename_seq, seq))
goto retry;

if (copy_to_user(arg, &ifr, sizeof(struct ifreq)))
diff --git a/net/core/sock.c b/net/core/sock.c
index a692ef4..bc131d4 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -583,7 +583,7 @@ static int sock_getbindtodevice(struct sock *sk, char __user *optval,
goto out;

retry:
- seq = read_seqbegin(&devnet_rename_seq);
+ seq = read_seqcount_begin(&devnet_rename_seq);
rcu_read_lock();
dev = dev_get_by_index_rcu(net, sk->sk_bound_dev_if);
ret = -ENODEV;
@@ -594,7 +594,7 @@ retry:

strcpy(devname, dev->name);
rcu_read_unlock();
- if (read_seqretry(&devnet_rename_seq, seq))
+ if (read_seqcount_retry(&devnet_rename_seq, seq))
goto retry;

len = strlen(devname) + 1;
--
1.7.11.7


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