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Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

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* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  rcu: rcu_read_lock_bh_held(): disabling irqs also disables bh
  generic-ipi: Fix deadlock in __smp_call_function_single
This commit is contained in:
Linus Torvalds 2010-10-05 13:07:43 -07:00
commit e1d9694cae
2 changed files with 15 additions and 4 deletions
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2
include/linux/rcupdate.h
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@ -454,7 +454,7 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
* Makes rcu_dereference_check() do the dirty work.
*/
#define rcu_dereference_bh(p) \
rcu_dereference_check(p, rcu_read_lock_bh_held())
rcu_dereference_check(p, rcu_read_lock_bh_held() || irqs_disabled())
/**
* rcu_dereference_sched - fetch RCU-protected pointer, checking for RCU-sched

17
kernel/smp.c
View file

@ -365,9 +365,10 @@ int smp_call_function_any(const struct cpumask *mask,
EXPORT_SYMBOL_GPL(smp_call_function_any);
/**
* __smp_call_function_single(): Run a function on another CPU
* __smp_call_function_single(): Run a function on a specific CPU
* @cpu: The CPU to run on.
* @data: Pre-allocated and setup data structure
* @wait: If true, wait until function has completed on specified CPU.
*
* Like smp_call_function_single(), but allow caller to pass in a
* pre-allocated data structure. Useful for embedding @data inside
@ -376,8 +377,10 @@ EXPORT_SYMBOL_GPL(smp_call_function_any);
void __smp_call_function_single(int cpu, struct call_single_data *data,
int wait)
{
csd_lock(data);
unsigned int this_cpu;
unsigned long flags;
this_cpu = get_cpu();
/*
* Can deadlock when called with interrupts disabled.
* We allow cpu's that are not yet online though, as no one else can
@ -387,7 +390,15 @@ void __smp_call_function_single(int cpu, struct call_single_data *data,
WARN_ON_ONCE(cpu_online(smp_processor_id()) && wait && irqs_disabled()
&& !oops_in_progress);
generic_exec_single(cpu, data, wait);
if (cpu == this_cpu) {
local_irq_save(flags);
data->func(data->info);
local_irq_restore(flags);
} else {
csd_lock(data);
generic_exec_single(cpu, data, wait);
}
put_cpu();
}
/**