* Re: linux-2.6.12-rc1-mm4-RT-V0.7.42-08
[not found] <1112433149.13131.8.camel@twins>
@ 2005-04-03 5:59 ` Peter Zijlstra
2005-04-04 17:40 ` linux-2.6.12-rc1-mm4-RT-V0.7.42-08 Ingo Molnar
0 siblings, 1 reply; 3+ messages in thread
From: Peter Zijlstra @ 2005-04-03 5:59 UTC (permalink / raw)
To: Ingo Molnar; +Cc: LKML
[-- Attachment #1: Type: text/plain, Size: 2344 bytes --]
Hi Ingo,
I need the following two patches to keep my system alive and avoid
the BUGs in the log send to you earlier (private mail).
------------------- example BUG ------------------------
BUG: using smp_processor_id() in preemptible [00000001] code: java/16460
caller is icmp_send+0x9b/0x3d0
[<c020b1db>] smp_processor_id+0x9b/0xb0 (8)
[<c032246b>] icmp_send+0x9b/0x3d0 (28)
[<c013ae67>] check_wakeup_timing+0x47/0x160 (8)
[<c034269d>] _raw_spin_unlock+0xd/0x30 (40)
[<c014d159>] kmem_cache_free+0x39/0x120 (8)
[<c034269d>] _raw_spin_unlock+0xd/0x30 (12)
[<c014d159>] kmem_cache_free+0x39/0x120 (8)
[<c034269d>] _raw_spin_unlock+0xd/0x30 (24)
[<c034269d>] _raw_spin_unlock+0xd/0x30 (28)
[<c0276066>] rtl8139_start_xmit+0x86/0x1d0 (8)
[<c034269d>] _raw_spin_unlock+0xd/0x30 (40)
[<c02f3259>] qdisc_restart+0x1b9/0x230 (8)
[<c02f3259>] qdisc_restart+0x1b9/0x230 (36)
[<c034269d>] _raw_spin_unlock+0xd/0x30 (8)
[<c02760ae>] rtl8139_start_xmit+0xce/0x1d0 (16)
[<c034269d>] _raw_spin_unlock+0xd/0x30 (32)
[<c02ffe33>] ip_fragment+0x663/0x7f0 (60)
[<c013138f>] rcu_read_unlock+0x5f/0x70 (32)
[<c02f9d2a>] __ip_route_output_key+0xba/0xe0 (8)
[<c02fe950>] ip_finish_output+0x0/0x2f0 (16)
[<c02ff383>] ip_queue_xmit+0x263/0x590 (24)
[<c02ff383>] ip_queue_xmit+0x263/0x590 (20)
[<c03102eb>] tcp_transmit_skb+0x38b/0x750 (196)
[<c031113e>] tcp_write_xmit+0x10e/0x2f0 (56)
[<c03054ab>] tcp_sendmsg+0xffb/0x1050 (52)
[<c034269d>] _raw_spin_unlock+0xd/0x30 (12)
[<c013b9c5>] unqueue_me+0x25/0x130 (8)
[<c0325f4a>] inet_sendmsg+0x4a/0x70 (92)
[<c02dd795>] sock_aio_write+0x135/0x150 (24)
[<c034269d>] _raw_spin_unlock+0xd/0x30 (88)
[<c0163c69>] do_sync_write+0xb9/0x110 (20)
[<c034269d>] _raw_spin_unlock+0xd/0x30 (44)
[<c0164d52>] fget_light+0x62/0x90 (8)
[<c034269d>] _raw_spin_unlock+0xd/0x30 (44)
[<c0134c50>] autoremove_wake_function+0x0/0x50 (8)
[<c0163d9b>] vfs_write+0xdb/0x170 (52)
[<c0163ee1>] sys_write+0x41/0x70 (24)
[<c0102f0b>] sysenter_past_esp+0x54/0x75 (28)
---------------------------
| preempt count: 00000002 ]
| 2-level deep critical section nesting:
----------------------------------------
.. [<c03422e6>] .... _raw_spin_lock+0x16/0x90
.....[<00000000>] .. ( <= 0x0)
.. [<c03422e6>] .... _raw_spin_lock+0x16/0x90
.....[<00000000>] .. ( <= 0x0)
--
Peter Zijlstra <a.p.zijlstra@chello.nl>
[-- Attachment #2: 2.6.12-rc1-icmp.patch --]
[-- Type: text/x-patch, Size: 903 bytes --]
Since there is no lock held yet we are still preemptable; and since
icmp_socket is a per cpu variable switching cpus gives weird results.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
--- /usr/src/linux-2.6.12-rc1-mm4-RT-V0.7.42-08/net/ipv4/icmp.c~ 2005-03-25 10:14:32.000000000 +0100
+++ /usr/src/linux-2.6.12-rc1-mm4-RT-V0.7.42-08/net/ipv4/icmp.c 2005-04-02 18:58:19.000000000 +0200
@@ -376,8 +376,8 @@
static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
{
- struct sock *sk = icmp_socket->sk;
- struct inet_sock *inet = inet_sk(sk);
+ struct sock *sk;
+ struct inet_sock *inet;
struct ipcm_cookie ipc;
struct rtable *rt = (struct rtable *)skb->dst;
u32 daddr;
@@ -388,6 +388,9 @@
if (icmp_xmit_lock())
return;
+ sk = icmp_socket->sk;
+ inet = inet_sk(sk);
+
icmp_param->data.icmph.checksum = 0;
icmp_out_count(icmp_param->data.icmph.type);
[-- Attachment #3: 2.6.12-rc1-icmp-rt.patch --]
[-- Type: text/x-patch, Size: 4296 bytes --]
Since on PREEMPT_RT spinlocks allow preemption, it's possible to
change cpu at (almost) any point in time. Make sure we stick to
the per cpu variable we started with.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
--- /usr/src/linux-2.6.12-rc1-mm4-RT-V0.7.42-08/net/ipv4/icmp_orig.c 2005-04-03 00:09:08.000000000 +0200
+++ /usr/src/linux-2.6.12-rc1-mm4-RT-V0.7.42-08/net/ipv4/icmp.c 2005-04-03 00:20:22.000000000 +0200
@@ -228,27 +228,32 @@
*
* On SMP we have one ICMP socket per-cpu.
*/
-static DEFINE_PER_CPU(struct socket *, __icmp_socket) = NULL;
-#define icmp_socket __get_cpu_var(__icmp_socket)
+static DEFINE_PER_CPU_LOCKED(struct socket *, __icmp_socket) = NULL;
static __inline__ struct socket * icmp_xmit_lock(int cpu)
{
+ struct socket *icmp_socket;
+
local_bh_disable();
+ icmp_socket = get_cpu_var_locked(__icmp_socket, cpu);
if (unlikely(!spin_trylock(&icmp_socket->sk->sk_lock.slock))) {
/* This can happen if the output path signals a
* dst_link_failure() for an outgoing ICMP packet.
*/
+ put_cpu_var_locked(__icmp_socket, cpu);
local_bh_enable();
- return 1;
+ return NULL;
}
- return 0;
+ return icmp_socket;
}
static void icmp_xmit_unlock(int cpu)
{
+ struct socket *icmp_socket = __get_cpu_var_locked(__icmp_socket, cpu);
spin_unlock_bh(&icmp_socket->sk->sk_lock.slock);
+ put_cpu_var_locked(__icmp_socket, cpu);
}
/*
@@ -345,7 +350,8 @@
}
static void icmp_push_reply(struct icmp_bxm *icmp_param,
- struct ipcm_cookie *ipc, struct rtable *rt)
+ struct ipcm_cookie *ipc, struct rtable *rt,
+ struct socket *icmp_socket)
{
struct sk_buff *skb;
@@ -377,16 +383,19 @@
static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
{
+ struct socket *icmp_socket;
struct sock *sk;
struct inet_sock *inet;
struct ipcm_cookie ipc;
struct rtable *rt = (struct rtable *)skb->dst;
u32 daddr;
+ int cpu;
if (ip_options_echo(&icmp_param->replyopts, skb))
goto out;
- if (icmp_xmit_lock())
+ cpu = _smp_processor_id();
+ if (!(icmp_socket = icmp_xmit_lock(cpu)))
return;
sk = icmp_socket->sk;
@@ -414,10 +423,10 @@
}
if (icmpv4_xrlim_allow(rt, icmp_param->data.icmph.type,
icmp_param->data.icmph.code))
- icmp_push_reply(icmp_param, &ipc, rt);
+ icmp_push_reply(icmp_param, &ipc, rt, icmp_socket);
ip_rt_put(rt);
out_unlock:
- icmp_xmit_unlock();
+ icmp_xmit_unlock(cpu);
out:;
}
@@ -435,8 +444,9 @@
void icmp_send(struct sk_buff *skb_in, int type, int code, u32 info)
{
+ struct socket *icmp_socket;
struct iphdr *iph;
- int room;
+ int room, cpu;
struct icmp_bxm icmp_param;
struct rtable *rt = (struct rtable *)skb_in->dst;
struct ipcm_cookie ipc;
@@ -507,7 +517,8 @@
}
}
- if (icmp_xmit_lock())
+ cpu = _smp_processor_id();
+ if (!(icmp_socket = icmp_xmit_lock(cpu)))
return;
/*
@@ -580,11 +591,11 @@
icmp_param.data_len = room;
icmp_param.head_len = sizeof(struct icmphdr);
- icmp_push_reply(&icmp_param, &ipc, rt);
+ icmp_push_reply(&icmp_param, &ipc, rt, icmp_socket);
ende:
ip_rt_put(rt);
out_unlock:
- icmp_xmit_unlock();
+ icmp_xmit_unlock(cpu);
out:;
}
@@ -1116,20 +1127,20 @@
continue;
err = sock_create_kern(PF_INET, SOCK_RAW, IPPROTO_ICMP,
- &per_cpu(__icmp_socket, i));
+ &__get_cpu_var_locked(__icmp_socket, i));
if (err < 0)
panic("Failed to create the ICMP control socket.\n");
- per_cpu(__icmp_socket, i)->sk->sk_allocation = GFP_ATOMIC;
+ __get_cpu_var_locked(__icmp_socket, i)->sk->sk_allocation = GFP_ATOMIC;
/* Enough space for 2 64K ICMP packets, including
* sk_buff struct overhead.
*/
- per_cpu(__icmp_socket, i)->sk->sk_sndbuf =
+ __get_cpu_var_locked(__icmp_socket, i)->sk->sk_sndbuf =
(2 * ((64 * 1024) + sizeof(struct sk_buff)));
- inet = inet_sk(per_cpu(__icmp_socket, i)->sk);
+ inet = inet_sk(__get_cpu_var_locked(__icmp_socket, i)->sk);
inet->uc_ttl = -1;
inet->pmtudisc = IP_PMTUDISC_DONT;
@@ -1137,7 +1148,7 @@
* see it, we do not wish this socket to see incoming
* packets.
*/
- per_cpu(__icmp_socket, i)->sk->sk_prot->unhash(per_cpu(__icmp_socket, i)->sk);
+ __get_cpu_var_locked(__icmp_socket, i)->sk->sk_prot->unhash(__get_cpu_var_locked(__icmp_socket, i)->sk);
}
}
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: linux-2.6.12-rc1-mm4-RT-V0.7.42-08
2005-04-03 5:59 ` linux-2.6.12-rc1-mm4-RT-V0.7.42-08 Peter Zijlstra
@ 2005-04-04 17:40 ` Ingo Molnar
2005-04-04 19:21 ` linux-2.6.12-rc1-mm4-RT-V0.7.42-08 Peter Zijlstra
0 siblings, 1 reply; 3+ messages in thread
From: Ingo Molnar @ 2005-04-04 17:40 UTC (permalink / raw)
To: Peter Zijlstra; +Cc: LKML
* Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> Hi Ingo,
>
> I need the following two patches to keep my system alive and avoid
> the BUGs in the log send to you earlier (private mail).
hm, the second patch does not apply (and the merge didnt look trivial) -
maybe it depends on some patch in -mm that is not yet upstream?
Ingo
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: linux-2.6.12-rc1-mm4-RT-V0.7.42-08
2005-04-04 17:40 ` linux-2.6.12-rc1-mm4-RT-V0.7.42-08 Ingo Molnar
@ 2005-04-04 19:21 ` Peter Zijlstra
0 siblings, 0 replies; 3+ messages in thread
From: Peter Zijlstra @ 2005-04-04 19:21 UTC (permalink / raw)
To: LKML
[-- Attachment #1: Type: text/plain, Size: 1144 bytes --]
On Mon, 2005-04-04 at 19:40 +0200, Ingo Molnar wrote:
> * Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
>
> > Hi Ingo,
> >
> > I need the following two patches to keep my system alive and avoid
> > the BUGs in the log send to you earlier (private mail).
>
> hm, the second patch does not apply (and the merge didnt look trivial) -
> maybe it depends on some patch in -mm that is not yet upstream?
>
I messed it up; apparently I type :wa to often and forgot to keep a
decent base file (yes I'm a vim user). I also seem to have gotten the
patch base dir wrong.
The two patches again; now hopefully with correct patch level and proper
base. They apply to my tree in order 2.6.12-rc1-icmp{,-rt}.patch.
Not ran nor compile tested on vanilla; just made then apply cleanly.
Could you please comment on the patches since I'm learning this stuff as
I go; and validation of my ideas would be most welcome. For instance;
was I right to convert the per cpu var __icmp_socket to a _LOCKED?
I think so since without the extra lock one could have race conditions
within the spin_trylock arguments double dereference.
Kind regards,
Peter Zijlstra
[-- Attachment #2: 2.6.12-rc1-icmp.patch --]
[-- Type: text/x-patch, Size: 881 bytes --]
Since there is no lock held yet we are still preemptable; and since
icmp_socket is a per cpu variable switching cpus gives weird results.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
--- linux-2.6.12-rc1-RT-V0.7.42-08/net/ipv4/icmp_base.c 2005-04-04 20:26:23.000000000 +0200
+++ linux-2.6.12-rc1-RT-V0.7.42-08/net/ipv4/icmp.c 2005-04-04 20:26:38.000000000 +0200
@@ -376,8 +376,8 @@
static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
{
- struct sock *sk = icmp_socket->sk;
- struct inet_sock *inet = inet_sk(sk);
+ struct sock *sk;
+ struct inet_sock *inet;
struct ipcm_cookie ipc;
struct rtable *rt = (struct rtable *)skb->dst;
u32 daddr;
@@ -388,6 +388,9 @@
if (icmp_xmit_lock())
return;
+ sk = icmp_socket->sk;
+ inet = inet_sk(sk);
+
icmp_param->data.icmph.checksum = 0;
icmp_out_count(icmp_param->data.icmph.type);
[-- Attachment #3: 2.6.12-rc1-icmp-rt.patch --]
[-- Type: text/x-patch, Size: 4348 bytes --]
Since on PREEMPT_RT spinlocks allow preemption, it's possible to
change cpu at (almost) any point in time. Make sure we stick to
the per cpu variable we started with.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
--- linux-2.6.12-rc1-RT-V0.7.42-08/net/ipv4/icmp_p1.c 2005-04-04 20:26:38.000000000 +0200
+++ linux-2.6.12-rc1-RT-V0.7.42-08/net/ipv4/icmp.c 2005-04-04 20:27:54.000000000 +0200
@@ -228,26 +228,32 @@
*
* On SMP we have one ICMP socket per-cpu.
*/
-static DEFINE_PER_CPU(struct socket *, __icmp_socket) = NULL;
-#define icmp_socket __get_cpu_var(__icmp_socket)
+static DEFINE_PER_CPU_LOCKED(struct socket *, __icmp_socket) = NULL;
-static __inline__ int icmp_xmit_lock(void)
+static __inline__ struct socket * icmp_xmit_lock(int cpu)
{
+ struct socket *icmp_socket;
+
local_bh_disable();
+ icmp_socket = get_cpu_var_locked(__icmp_socket, cpu);
if (unlikely(!spin_trylock(&icmp_socket->sk->sk_lock.slock))) {
/* This can happen if the output path signals a
* dst_link_failure() for an outgoing ICMP packet.
*/
+ put_cpu_var_locked(__icmp_socket, cpu);
local_bh_enable();
- return 1;
+ return NULL;
}
- return 0;
+
+ return icmp_socket;
}
-static void icmp_xmit_unlock(void)
+static void icmp_xmit_unlock(int cpu)
{
+ struct socket *icmp_socket = __get_cpu_var_locked(__icmp_socket, cpu);
spin_unlock_bh(&icmp_socket->sk->sk_lock.slock);
+ put_cpu_var_locked(__icmp_socket, cpu);
}
/*
@@ -344,7 +350,8 @@
}
static void icmp_push_reply(struct icmp_bxm *icmp_param,
- struct ipcm_cookie *ipc, struct rtable *rt)
+ struct ipcm_cookie *ipc, struct rtable *rt,
+ struct socket *icmp_socket)
{
struct sk_buff *skb;
@@ -376,16 +383,19 @@
static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
{
+ struct socket *icmp_socket;
struct sock *sk;
struct inet_sock *inet;
struct ipcm_cookie ipc;
struct rtable *rt = (struct rtable *)skb->dst;
u32 daddr;
+ int cpu;
if (ip_options_echo(&icmp_param->replyopts, skb))
goto out;
- if (icmp_xmit_lock())
+ cpu = _smp_processor_id();
+ if (!(icmp_socket = icmp_xmit_lock(cpu)))
return;
sk = icmp_socket->sk;
@@ -413,10 +423,10 @@
}
if (icmpv4_xrlim_allow(rt, icmp_param->data.icmph.type,
icmp_param->data.icmph.code))
- icmp_push_reply(icmp_param, &ipc, rt);
+ icmp_push_reply(icmp_param, &ipc, rt, icmp_socket);
ip_rt_put(rt);
out_unlock:
- icmp_xmit_unlock();
+ icmp_xmit_unlock(cpu);
out:;
}
@@ -434,8 +444,9 @@
void icmp_send(struct sk_buff *skb_in, int type, int code, u32 info)
{
+ struct socket *icmp_socket;
struct iphdr *iph;
- int room;
+ int room, cpu;
struct icmp_bxm icmp_param;
struct rtable *rt = (struct rtable *)skb_in->dst;
struct ipcm_cookie ipc;
@@ -506,7 +517,8 @@
}
}
- if (icmp_xmit_lock())
+ cpu = _smp_processor_id();
+ if (!(icmp_socket = icmp_xmit_lock(cpu)))
return;
/*
@@ -579,11 +591,11 @@
icmp_param.data_len = room;
icmp_param.head_len = sizeof(struct icmphdr);
- icmp_push_reply(&icmp_param, &ipc, rt);
+ icmp_push_reply(&icmp_param, &ipc, rt, icmp_socket);
ende:
ip_rt_put(rt);
out_unlock:
- icmp_xmit_unlock();
+ icmp_xmit_unlock(cpu);
out:;
}
@@ -1115,20 +1127,20 @@
continue;
err = sock_create_kern(PF_INET, SOCK_RAW, IPPROTO_ICMP,
- &per_cpu(__icmp_socket, i));
+ &__get_cpu_var_locked(__icmp_socket, i));
if (err < 0)
panic("Failed to create the ICMP control socket.\n");
- per_cpu(__icmp_socket, i)->sk->sk_allocation = GFP_ATOMIC;
+ __get_cpu_var_locked(__icmp_socket, i)->sk->sk_allocation = GFP_ATOMIC;
/* Enough space for 2 64K ICMP packets, including
* sk_buff struct overhead.
*/
- per_cpu(__icmp_socket, i)->sk->sk_sndbuf =
+ __get_cpu_var_locked(__icmp_socket, i)->sk->sk_sndbuf =
(2 * ((64 * 1024) + sizeof(struct sk_buff)));
- inet = inet_sk(per_cpu(__icmp_socket, i)->sk);
+ inet = inet_sk(__get_cpu_var_locked(__icmp_socket, i)->sk);
inet->uc_ttl = -1;
inet->pmtudisc = IP_PMTUDISC_DONT;
@@ -1136,7 +1148,7 @@
* see it, we do not wish this socket to see incoming
* packets.
*/
- per_cpu(__icmp_socket, i)->sk->sk_prot->unhash(per_cpu(__icmp_socket, i)->sk);
+ __get_cpu_var_locked(__icmp_socket, i)->sk->sk_prot->unhash(__get_cpu_var_locked(__icmp_socket, i)->sk);
}
}
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2005-04-04 19:23 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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[not found] <1112433149.13131.8.camel@twins>
2005-04-03 5:59 ` linux-2.6.12-rc1-mm4-RT-V0.7.42-08 Peter Zijlstra
2005-04-04 17:40 ` linux-2.6.12-rc1-mm4-RT-V0.7.42-08 Ingo Molnar
2005-04-04 19:21 ` linux-2.6.12-rc1-mm4-RT-V0.7.42-08 Peter Zijlstra
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