[PATCH 7/8] percpu: add __percpu sparse annotations to hw_breakpoint

Tejun Heo
2010-01-25T15:19:56Z

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.

per_cpu(nr_task_bp_pinned, cpu) is replaced with
&per_cpu(nr_task_bp_pinned[0], cpu). This is the same to the compiler
but allows per_cpu() macro to correctly drop __percpu designation for
the returned pointer.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
---
include/linux/hw_breakpoint.h | 8 ++++----
kernel/hw_breakpoint.c | 14 +++++++-------
samples/hw_breakpoint/data_breakpoint.c | 6 +++---
3 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/include/linux/hw_breakpoint.h b/include/linux/hw_breakpoint.h
index 41235c9..f462d3d 100644
--- a/include/linux/hw_breakpoint.h
+++ b/include/linux/hw_breakpoint.h
@@ -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 reserve_bp_slot(struct perf_event *bp);
extern void release_bp_slot(struct perf_event *bp);
@@ -98,7 +98,7 @@ 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
@@ -107,7 +107,7 @@ 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) { }
diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c
index 50dbd59..11dae6d 100644
--- a/kernel/hw_breakpoint.c
+++ b/kernel/hw_breakpoint.c
@@ -74,7 +74,7 @@ static DEFINE_MUTEX(nr_bp_mutex);
static unsigned int max_task_bp_pinned(int cpu)
{
int i;
- unsigned int *tsk_pinned = per_cpu(nr_task_bp_pinned, cpu);
+ unsigned int *tsk_pinned = &per_cpu(nr_task_bp_pinned[0], cpu);

for (i = HBP_NUM -1; i >= 0; i--) {
if (tsk_pinned[i] > 0)
@@ -163,7 +163,7 @@ static void toggle_bp_task_slot(struct task_struct *tsk, int cpu, bool enable)

count = task_bp_pinned(tsk);

- tsk_pinned = per_cpu(nr_task_bp_pinned, cpu);
+ tsk_pinned = &per_cpu(nr_task_bp_pinned[0], cpu);
if (enable) {
tsk_pinned[count]++;
if (count > 0)
@@ -377,17 +377,17 @@ 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) {
@@ -415,7 +415,7 @@ 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);

@@ -423,7 +423,7 @@ 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;
diff --git a/samples/hw_breakpoint/data_breakpoint.c b/samples/hw_breakpoint/data_breakpoint.c
index c69cbe9..bd0f337 100644
--- a/samples/hw_breakpoint/data_breakpoint.c
+++ b/samples/hw_breakpoint/data_breakpoint.c
@@ -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;
}

--
1.6.4.2