Commit-ID: b29f39c7c3e75a741a7da88244ec707f293ec04c
Gitweb: http://git.kernel.org/tip/b29f39c7c3e75a741a7da88244ec707f293ec04c
Author: Chuansheng Liu <chuansheng....@intel.com>
AuthorDate: Wed, 6 Feb 2013 23:18:21 +0800
Committer: Ingo Molnar <mi...@kernel.org>
CommitDate: Wed, 6 Feb 2013 12:00:30 +0100
smp: Give WARN()ing if in_interrupt() when calling
smp_call_function_many()/single()
Currently the functions smp_call_function_many()/single() will
give a WARN()ing only in the case of irqs_disabled(), but that
check is not enough to guarantee execution of the SMP
cross-calls.
In many other cases such as softirq handling/interrupt handling,
the two APIs still can not be called, just as the
smp_call_function_many() comments say:
* You must not call this function with disabled interrupts or from a
* hardware interrupt handler or from a bottom half handler. Preemption
* must be disabled when calling this function.
There is a real case for softirq DEADLOCK case:
CPUA CPUB
spin_lock(&spinlock)
Any irq coming, call the irq handler
irq_exit()
spin_lock_irq(&spinlock)
<== Blocking here due to
CPUB hold it
__do_softirq()
run_timer_softirq()
timer_cb()
call smp_call_function_many()
send IPI interrupt to CPUA
wait_csd()
Then both CPUA and CPUB will be deadlocked here.
So we should give a warning in the in_interrupt() case as well.
Signed-off-by: liu chuansheng <chuansheng....@intel.com>
Cc: jun.zh...@intel.com
Cc: pet...@infradead.org
Cc: jbeul...@suse.com
Cc: paul...@linux.vnet.ibm.com
Cc: min...@mina86.org
Cc: srivatsa.b...@linux.vnet.ibm.com
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijls...@chello.nl>
Link: http://lkml.kernel.org/r/1360163901.24670.13.camel@cliu38-desktop-build
Signed-off-by: Ingo Molnar <mi...@kernel.org>
---
kernel/smp.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/kernel/smp.c b/kernel/smp.c
index 29dd40a..fec45aa 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -12,6 +12,7 @@
#include <linux/gfp.h>
#include <linux/smp.h>
#include <linux/cpu.h>
+#include <linux/hardirq.h>
#include "smpboot.h"
@@ -318,7 +319,7 @@ 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()
+ WARN_ON_ONCE(cpu_online(this_cpu) && (irqs_disabled() || in_interrupt())
&& !oops_in_progress);
if (cpu == this_cpu) {
@@ -416,8 +417,9 @@ 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()
- && !oops_in_progress);
+ WARN_ON_ONCE(cpu_online(smp_processor_id()) && wait
+ && (irqs_disabled() || in_interrupt())
+ && !oops_in_progress);
if (cpu == this_cpu) {
local_irq_save(flags);
--
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