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: Tejun 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: Frederic Weisbecker <fweisbec@gmail.com>

1 files changed, 5 insertions, 5 deletions

diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c
index 967e66143e11..6542eacb3fa5 100644
--- a/kernel/hw_breakpoint.c
+++ b/kernel/hw_breakpoint.c
@@ -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;