Currently, in function smp_call_function_many/single, it will give WARN just in
case
of irqs_disabled(), but it is not enough.
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 said:
* 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 DEADLOCK here.
So we should give WARN in case of in_interrupt(), not only irqd_disabled().
Signed-off-by: liu chuansheng <chuansheng....@intel.com>
---
kernel/smp.c | 8 +++++---
1 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/kernel/smp.c b/kernel/smp.c
index 69f38bd..a2f0b2c 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"
@@ -323,7 +324,7 @@ 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) {
@@ -421,8 +422,9 @@ 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);
--
1.7.0.4
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