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Subject[tip:core/ipi] generic-ipi: eliminate spurious pointless WARN_ON()s
Commit-ID:  6a09dfa870ba0ed21b1124539968a36b42660661
Gitweb: http://git.kernel.org/tip/6a09dfa870ba0ed21b1124539968a36b42660661
Author: Jan Beulich <jbeulich@novell.com>
AuthorDate: Thu, 12 Mar 2009 13:21:50 +0000
Commit: Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 13 Mar 2009 02:14:41 +0100
generic-ipi: eliminate spurious pointless WARN_ON()s

Namely during early boot, the panic() or BUG() paths may end up in
smp_call_function_*() with just a single online CPU. In that situation
the warnings generated are not only meaningless, but also result in
relevant output being cluttered.

Therefore, defer the WARN_ON() checks until after the (unaffected from
the problem that is being attempted to be detected here) cases have
been handled.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
LKML-Reference: <49B91A7E.76E4.0078.0@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
kernel/smp.c | 12 ++++++------
1 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/kernel/smp.c b/kernel/smp.c
index 7ad2262..37b90a9 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -284,9 +284,6 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
*/
this_cpu = get_cpu();

- /* Can deadlock when called with interrupts disabled */
- WARN_ON(irqs_disabled());
-
if (cpu == this_cpu) {
local_irq_save(flags);
func(info);
@@ -295,6 +292,9 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
if ((unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) {
struct call_single_data *data = &d;

+ /* Can deadlock when called with interrupts disabled */
+ WARN_ON(irqs_disabled());
+
if (!wait)
data = &__get_cpu_var(csd_data);

@@ -364,9 +364,6 @@ void smp_call_function_many(const struct cpumask *mask,
unsigned long flags;
int cpu, next_cpu, this_cpu = smp_processor_id();

- /* Can deadlock when called with interrupts disabled */
- WARN_ON(irqs_disabled());
-
/* So, what's a CPU they want? Ignoring this one. */
cpu = cpumask_first_and(mask, cpu_online_mask);
if (cpu == this_cpu)
@@ -387,6 +384,9 @@ void smp_call_function_many(const struct cpumask *mask,
return;
}

+ /* Can deadlock when called with interrupts disabled */
+ WARN_ON(irqs_disabled());
+
data = &__get_cpu_var(cfd_data);
csd_lock(&data->csd);


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