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Commit 44ee6358 authored by Tejun Heo's avatar Tejun Heo Committed by Frederic Weisbecker
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percpu: Add __percpu sparse annotations to hw_breakpoint 



Add __percpu sparse annotations to hw_breakpoint.

These annotations are to make sparse consider percpu variables to be
in a different address space and warn if accessed without going
through percpu accessors.  This patch doesn't affect normal builds.

In kernel/hw_breakpoint.c, per_cpu(nr_task_bp_pinned, cpu)'s will
trigger spurious noderef related warnings from sparse.  Changing it to
&per_cpu(nr_task_bp_pinned[0], cpu) will work around the problem but
deemed to ugly by the maintainer.  Leave it alone until better
solution can be found.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
LKML-Reference: <4B7B4B7A.9050902@kernel.org>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
parent 018cbffe

include/linux/hw_breakpoint.h

+4 −4
Original line number Diff line number Diff line
@@ -66,14 +66,14 @@ register_wide_hw_breakpoint_cpu(struct perf_event_attr *attr, 
				perf_overflow_handler_t	triggered,

				int cpu);



extern struct perf_event **

extern struct perf_event * __percpu *

register_wide_hw_breakpoint(struct perf_event_attr *attr,

			    perf_overflow_handler_t triggered);



extern int register_perf_hw_breakpoint(struct perf_event *bp);

extern int __register_perf_hw_breakpoint(struct perf_event *bp);

extern void unregister_hw_breakpoint(struct perf_event *bp);

extern void unregister_wide_hw_breakpoint(struct perf_event **cpu_events);

extern void unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events);



extern int dbg_reserve_bp_slot(struct perf_event *bp);

extern int dbg_release_bp_slot(struct perf_event *bp);
@@ -100,7 +100,7 @@ static inline struct perf_event * 
register_wide_hw_breakpoint_cpu(struct perf_event_attr *attr,

				perf_overflow_handler_t	 triggered,

				int cpu)		{ return NULL; }

static inline struct perf_event **

static inline struct perf_event * __percpu *

register_wide_hw_breakpoint(struct perf_event_attr *attr,

			    perf_overflow_handler_t triggered)	{ return NULL; }

static inline int
@@ -109,7 +109,7 @@ static inline int 
__register_perf_hw_breakpoint(struct perf_event *bp) 	{ return -ENOSYS; }

static inline void unregister_hw_breakpoint(struct perf_event *bp)	{ }

static inline void

unregister_wide_hw_breakpoint(struct perf_event **cpu_events)		{ }

unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events)	{ }

static inline int

reserve_bp_slot(struct perf_event *bp)			{return -ENOSYS; }

static inline void release_bp_slot(struct perf_event *bp) 		{ }

kernel/hw_breakpoint.c

+5 −5
Original line number Diff line number Diff line
@@ -413,17 +413,17 @@ EXPORT_SYMBOL_GPL(unregister_hw_breakpoint); 
 *

 * @return a set of per_cpu pointers to perf events

 */

struct perf_event **

struct perf_event * __percpu *

register_wide_hw_breakpoint(struct perf_event_attr *attr,

			    perf_overflow_handler_t triggered)

{

	struct perf_event **cpu_events, **pevent, *bp;

	struct perf_event * __percpu *cpu_events, **pevent, *bp;

	long err;

	int cpu;



	cpu_events = alloc_percpu(typeof(*cpu_events));

	if (!cpu_events)

		return ERR_PTR(-ENOMEM);

		return (void __percpu __force *)ERR_PTR(-ENOMEM);



	get_online_cpus();

	for_each_online_cpu(cpu) {
@@ -451,7 +451,7 @@ fail: 
	put_online_cpus();



	free_percpu(cpu_events);

	return ERR_PTR(err);

	return (void __percpu __force *)ERR_PTR(err);

}

EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint);
@@ -459,7 +459,7 @@ EXPORT_SYMBOL_GPL(register_wide_hw_breakpoint); 
 * unregister_wide_hw_breakpoint - unregister a wide breakpoint in the kernel

 * @cpu_events: the per cpu set of events to unregister

 */

void unregister_wide_hw_breakpoint(struct perf_event **cpu_events)

void unregister_wide_hw_breakpoint(struct perf_event * __percpu *cpu_events)

{

	int cpu;

	struct perf_event **pevent;

samples/hw_breakpoint/data_breakpoint.c

+3 −3
Original line number Diff line number Diff line
@@ -34,7 +34,7 @@ 
#include <linux/perf_event.h>

#include <linux/hw_breakpoint.h>



struct perf_event **sample_hbp;

struct perf_event * __percpu *sample_hbp;



static char ksym_name[KSYM_NAME_LEN] = "pid_max";

module_param_string(ksym, ksym_name, KSYM_NAME_LEN, S_IRUGO);
@@ -61,8 +61,8 @@ static int __init hw_break_module_init(void) 
	attr.bp_type = HW_BREAKPOINT_W | HW_BREAKPOINT_R;



	sample_hbp = register_wide_hw_breakpoint(&attr, sample_hbp_handler);

	if (IS_ERR(sample_hbp)) {

		ret = PTR_ERR(sample_hbp);

	if (IS_ERR((void __force *)sample_hbp)) {

		ret = PTR_ERR((void __force *)sample_hbp);

		goto fail;

	}