[tip:core/locking] Revert "smp: Give WARN()ing if in_interrupt() when calling smp_call_function_many()/single()"

From: tip-bot for Ingo Molnar
Date: Mon Feb 11 2013 - 07:20:51 EST


Commit-ID: 56624143151fdb84c32a43463864e6c12a5ebcfc
Gitweb: http://git.kernel.org/tip/56624143151fdb84c32a43463864e6c12a5ebcfc
Author: Ingo Molnar <mingo@xxxxxxxxxx>
AuthorDate: Mon, 11 Feb 2013 10:03:29 +0100
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 11 Feb 2013 10:03:29 +0100

Revert "smp: Give WARN()ing if in_interrupt() when calling smp_call_function_many()/single()"

This reverts commit b29f39c7c3e75a741a7da88244ec707f293ec04c.

Fengguang Wu reported that the commit triggers a bogus warning
on the current networking tree:

[ 229.339945] Call Trace:
[ 229.341176] [<ffffffff810353b4>] warn_slowpath_common+0x83/0x9c
[ 229.343091] [<ffffffff817089d6>] ? flow_cache_new_hashrnd+0x98/0x98
[ 229.345105] [<ffffffff810353e7>] warn_slowpath_null+0x1a/0x1c
[ 229.346978] [<ffffffff81090793>] smp_call_function_single+0xbd/0x1c7
[ 229.349017] [<ffffffff81090afe>] smp_call_function_many+0x121/0x23e
[ 229.350996] [<ffffffff817089d6>] ? flow_cache_new_hashrnd+0x98/0x98
[ 229.353005] [<ffffffff81090e09>] smp_call_function+0x37/0x40
[ 229.354860] [<ffffffff8170907e>] flow_cache_flush+0x72/0xa0
[ 229.356735] [<ffffffff81759e33>] xfrm_dev_event+0x14/0x20
[ 229.358545] [<ffffffff817ff8b0>] notifier_call_chain+0x65/0x95
[ 229.360469] [<ffffffff8105ce16>] __raw_notifier_call_chain+0xe/0x10
[ 229.362453] [<ffffffff8105ce2c>] raw_notifier_call_chain+0x14/0x16
[ 229.364453] [<ffffffff816f63d6>] call_netdevice_notifiers+0x4a/0x4f
[ 229.366434] [<ffffffff816fa2ab>] __dev_notify_flags+0x37/0x5b
[ 229.368342] [<ffffffff816fa318>] dev_change_flags+0x49/0x54
[ 229.370184] [<ffffffff8174574a>] devinet_ioctl+0x24f/0x542
[ 229.372036] [<ffffffff81746975>] inet_ioctl+0x97/0xb1
[ 229.373774] [<ffffffff816e5042>] sock_do_ioctl.constprop.42+0x18/0x37
[ 229.375791] [<ffffffff816e5480>] sock_ioctl+0x1fd/0x20a
[ 229.377648] [<ffffffff810bb9cd>] ? trace_buffer_lock_reserve+0x41/0x56
[ 229.379701] [<ffffffff8112b7c6>] vfs_ioctl+0x26/0x39
[ 229.381459] [<ffffffff8112c0d2>] do_vfs_ioctl+0x41b/0x45e
[ 229.383269] [<ffffffff8100bc3a>] ? ftrace_raw_event_sys_enter+0x10b/0x11a
[ 229.385404] [<ffffffff817fc118>] ? retint_swapgs+0x13/0x1b
[ 229.387227] [<ffffffff8112c15a>] sys_ioctl+0x45/0x73
[ 229.388975] [<ffffffff818034be>] tracesys+0xd0/0xd5

The intention of the warning is to warn about IPIs generated from
hardirq contexts. But in_interrupt() will also warn from
softirq-disabled contexts.

The warning should probably use in_irq() - but that primitive
is not avaiable on non-genirq platform. So this change needs
more work - revert it until it's ready.

Reported-by: Fengguang Wu <fengguang.wu@xxxxxxxxx>
Cc: liu chuansheng <chuansheng.liu@xxxxxxxxx>
Cc: jun.zhang@xxxxxxxxx
Cc: peterz@xxxxxxxxxxxxx
Cc: jbeulich@xxxxxxxx
Cc: paulmck@xxxxxxxxxxxxxxxxxx
Cc: mina86@xxxxxxxxxx
Cc: srivatsa.bhat@xxxxxxxxxxxxxxxxxx
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1360163901.24670.13.camel@cliu38-desktop-build
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/smp.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/kernel/smp.c b/kernel/smp.c
index a2f0b2c..69f38bd 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -12,7 +12,6 @@
#include <linux/gfp.h>
#include <linux/smp.h>
#include <linux/cpu.h>
-#include <linux/hardirq.h>

#include "smpboot.h"

@@ -324,7 +323,7 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
* send smp call function interrupt to this cpu and as such deadlocks
* can't happen.
*/
- WARN_ON_ONCE(cpu_online(this_cpu) && (irqs_disabled() || in_interrupt())
+ WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
&& !oops_in_progress);

if (cpu == this_cpu) {
@@ -422,9 +421,8 @@ void __smp_call_function_single(int cpu, struct call_single_data *data,
* send smp call function interrupt to this cpu and as such deadlocks
* can't happen.
*/
- WARN_ON_ONCE(cpu_online(smp_processor_id()) && wait
- && (irqs_disabled() || in_interrupt())
- && !oops_in_progress);
+ WARN_ON_ONCE(cpu_online(smp_processor_id()) && wait && irqs_disabled()
+ && !oops_in_progress);

if (cpu == this_cpu) {
local_irq_save(flags);
--
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