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net: Fix percpu counters deadlock 

When we converted the protocol atomic counters such as the orphan
count and the total socket count deadlocks were introduced due to
the mismatch in BH status of the spots that used the percpu counter
operations.

Based on the diagnosis and patch by Peter Zijlstra, this patch
fixes these issues by disabling BH where we may be in process
context.

Reported-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Tested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu 2008-12-29 23:04:08 -08:00 committed by David S. Miller
parent 0f23174aa8
commit eb4dea5853
6 changed files with 21 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
net/dccp/proto.c
View File

@ -964,7 +964,6 @@ adjudge_to_death:
state = sk->sk_state;
sock_hold(sk);
sock_orphan(sk);
percpu_counter_inc(sk->sk_prot->orphan_count);
/*
* It is the last release_sock in its life. It will remove backlog.
@ -978,6 +977,8 @@ adjudge_to_death:
bh_lock_sock(sk);
WARN_ON(sock_owned_by_user(sk));
percpu_counter_inc(sk->sk_prot->orphan_count);
/* Have we already been destroyed by a softirq or backlog? */
if (state != DCCP_CLOSED && sk->sk_state == DCCP_CLOSED)
goto out;

4
net/ipv4/inet_connection_sock.c
View File

@ -633,8 +633,6 @@ void inet_csk_listen_stop(struct sock *sk)
acc_req = req->dl_next;
percpu_counter_inc(sk->sk_prot->orphan_count);
local_bh_disable();
bh_lock_sock(child);
WARN_ON(sock_owned_by_user(child));
@ -644,6 +642,8 @@ void inet_csk_listen_stop(struct sock *sk)
sock_orphan(child);
percpu_counter_inc(sk->sk_prot->orphan_count);
inet_csk_destroy_sock(child);
bh_unlock_sock(child);

13
net/ipv4/proc.c
View File

@ -38,6 +38,7 @@
#include <net/tcp.h>
#include <net/udp.h>
#include <net/udplite.h>
#include <linux/bottom_half.h>
#include <linux/inetdevice.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
@ -50,13 +51,17 @@
static int sockstat_seq_show(struct seq_file *seq, void *v)
{
struct net *net = seq->private;
int orphans, sockets;
local_bh_disable();
orphans = percpu_counter_sum_positive(&tcp_orphan_count),
sockets = percpu_counter_sum_positive(&tcp_sockets_allocated),
local_bh_enable();
socket_seq_show(seq);
seq_printf(seq, "TCP: inuse %d orphan %d tw %d alloc %d mem %d\n",
sock_prot_inuse_get(net, &tcp_prot),
(int)percpu_counter_sum_positive(&tcp_orphan_count),
tcp_death_row.tw_count,
(int)percpu_counter_sum_positive(&tcp_sockets_allocated),
sock_prot_inuse_get(net, &tcp_prot), orphans,
tcp_death_row.tw_count, sockets,
atomic_read(&tcp_memory_allocated));
seq_printf(seq, "UDP: inuse %d mem %d\n",
sock_prot_inuse_get(net, &udp_prot),

3
net/ipv4/tcp.c
View File

@ -1836,7 +1836,6 @@ adjudge_to_death:
state = sk->sk_state;
sock_hold(sk);
sock_orphan(sk);
percpu_counter_inc(sk->sk_prot->orphan_count);
/* It is the last release_sock in its life. It will remove backlog. */
release_sock(sk);
@ -1849,6 +1848,8 @@ adjudge_to_death:
bh_lock_sock(sk);
WARN_ON(sock_owned_by_user(sk));
percpu_counter_inc(sk->sk_prot->orphan_count);
/* Have we already been destroyed by a softirq or backlog? */
if (state != TCP_CLOSE && sk->sk_state == TCP_CLOSE)
goto out;

3
net/ipv4/tcp_ipv4.c
View File

@ -51,6 +51,7 @@
*/
#include <linux/bottom_half.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/module.h>
@ -1797,7 +1798,9 @@ static int tcp_v4_init_sock(struct sock *sk)
sk->sk_sndbuf = sysctl_tcp_wmem[1];
sk->sk_rcvbuf = sysctl_tcp_rmem[1];
local_bh_disable();
percpu_counter_inc(&tcp_sockets_allocated);
local_bh_enable();
return 0;
}

3
net/ipv6/tcp_ipv6.c
View File

@ -23,6 +23,7 @@
* 2 of the License, or (at your option) any later version.
*/
#include <linux/bottom_half.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/types.h>
@ -1830,7 +1831,9 @@ static int tcp_v6_init_sock(struct sock *sk)
sk->sk_sndbuf = sysctl_tcp_wmem[1];
sk->sk_rcvbuf = sysctl_tcp_rmem[1];
local_bh_disable();
percpu_counter_inc(&tcp_sockets_allocated);
local_bh_enable();
return 0;
}