[PATCH 1/2] hw_breakpoint: Simplify *register_wide_hw_breakpoint()

From: Oleg Nesterov
Date: Sun Jun 02 2013 - 15:55:10 EST


1. register_wide_hw_breakpoint() can use unregister_ if failure,
no need to duplicate the code.

2. "struct perf_event **pevent" adds the unnecesary lever of
indirection and complication, use per_cpu(*cpu_events, cpu).

Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
---
kernel/events/hw_breakpoint.c | 34 +++++++++++-----------------------
1 files changed, 11 insertions(+), 23 deletions(-)

diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
index 74d739b..17d8093 100644
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -497,8 +497,8 @@ register_wide_hw_breakpoint(struct perf_event_attr *attr,
perf_overflow_handler_t triggered,
void *context)
{
- struct perf_event * __percpu *cpu_events, **pevent, *bp;
- long err;
+ struct perf_event * __percpu *cpu_events, *bp;
+ long err = 0;
int cpu;

cpu_events = alloc_percpu(typeof(*cpu_events));
@@ -507,31 +507,21 @@ register_wide_hw_breakpoint(struct perf_event_attr *attr,

get_online_cpus();
for_each_online_cpu(cpu) {
- pevent = per_cpu_ptr(cpu_events, cpu);
bp = perf_event_create_kernel_counter(attr, cpu, NULL,
triggered, context);
-
- *pevent = bp;
-
if (IS_ERR(bp)) {
err = PTR_ERR(bp);
- goto fail;
+ break;
}
- }
- put_online_cpus();
-
- return cpu_events;

-fail:
- for_each_online_cpu(cpu) {
- pevent = per_cpu_ptr(cpu_events, cpu);
- if (IS_ERR(*pevent))
- break;
- unregister_hw_breakpoint(*pevent);
+ per_cpu(*cpu_events, cpu) = bp;
}
put_online_cpus();

- free_percpu(cpu_events);
+ if (likely(!err))
+ return cpu_events;
+
+ unregister_wide_hw_breakpoint(cpu_events);
return (void __percpu __force *)ERR_PTR(err);
}
EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint);
@@ -543,12 +533,10 @@ EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint);
void unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events)
{
int cpu;
- struct perf_event **pevent;

- for_each_possible_cpu(cpu) {
- pevent = per_cpu_ptr(cpu_events, cpu);
- unregister_hw_breakpoint(*pevent);
- }
+ for_each_possible_cpu(cpu)
+ unregister_hw_breakpoint(per_cpu(*cpu_events, cpu));
+
free_percpu(cpu_events);
}
EXPORT_SYMBOL_GPL(unregister_wide_hw_breakpoint);
--
1.5.5.1


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/