perf/hwbp: Simplify the perf-hwbp code, fix documentation

[pandora-kernel.git] / kernel / events / hw_breakpoint.c

diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
index b7971d6..eeb84bb 100644 (file)
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -147,7 +147,7 @@ fetch_bp_busy_slots(struct bp_busy_slots *slots, struct perf_event *bp,
                return;
        }
 
-       for_each_online_cpu(cpu) {
+       for_each_possible_cpu(cpu) {
                unsigned int nr;
 
                nr = per_cpu(nr_cpu_bp_pinned[type], cpu);
@@ -233,7 +233,7 @@ toggle_bp_slot(struct perf_event *bp, bool enable, enum bp_type_idx type,
        if (cpu >= 0) {
                toggle_bp_task_slot(bp, cpu, enable, type, weight);
        } else {
-               for_each_online_cpu(cpu)
+               for_each_possible_cpu(cpu)
                        toggle_bp_task_slot(bp, cpu, enable, type, weight);
        }
 
@@ -443,42 +443,35 @@ EXPORT_SYMBOL_GPL(register_user_hw_breakpoint);
  * modify_user_hw_breakpoint - modify a user-space hardware breakpoint
  * @bp: the breakpoint structure to modify
  * @attr: new breakpoint attributes
- * @triggered: callback to trigger when we hit the breakpoint
- * @tsk: pointer to 'task_struct' of the process to which the address belongs
  */
 int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr)
 {
-       u64 old_addr = bp->attr.bp_addr;
-       u64 old_len = bp->attr.bp_len;
-       int old_type = bp->attr.bp_type;
-       int err = 0;
-
-       perf_event_disable(bp);
+       /*
+        * modify_user_hw_breakpoint can be invoked with IRQs disabled and hence it
+        * will not be possible to raise IPIs that invoke __perf_event_disable.
+        * So call the function directly after making sure we are targeting the
+        * current task.
+        */
+       if (irqs_disabled() && bp->ctx && bp->ctx->task == current)
+               __perf_event_disable(bp);
+       else
+               perf_event_disable(bp);
 
        bp->attr.bp_addr = attr->bp_addr;
        bp->attr.bp_type = attr->bp_type;
        bp->attr.bp_len = attr->bp_len;
+       bp->attr.disabled = 1;
 
-       if (attr->disabled)
-               goto end;
-
-       err = validate_hw_breakpoint(bp);
-       if (!err)
-               perf_event_enable(bp);
+       if (!attr->disabled) {
+               int err = validate_hw_breakpoint(bp);
 
-       if (err) {
-               bp->attr.bp_addr = old_addr;
-               bp->attr.bp_type = old_type;
-               bp->attr.bp_len = old_len;
-               if (!bp->attr.disabled)
-                       perf_event_enable(bp);
+               if (err)
+                       return err;
 
-               return err;
+               perf_event_enable(bp);
+               bp->attr.disabled = 0;
        }
 
-end:
-       bp->attr.disabled = attr->disabled;
-
        return 0;
 }
 EXPORT_SYMBOL_GPL(modify_user_hw_breakpoint);