The enable/disable logic in toggle_bp_slot() is not symmetrical
and imho very confusing. "old_count" in toggle_bp_task_slot() is
actually new_count because this bp was already removed from the
list.
Change toggle_bp_slot() to always call list_add/list_del after
toggle_bp_task_slot(). This way old_idx is task_bp_pinned() and
this entry should be decremented, new_idx is +/-weight and we
need to increment this element. The code/logic looks obvious.
Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20130620155011.GA6330@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
static void toggle_bp_task_slot(struct perf_event *bp, int cpu, bool enable,
enum bp_type_idx type, int weight)
{
static void toggle_bp_task_slot(struct perf_event *bp, int cpu, bool enable,
enum bp_type_idx type, int weight)
{
- unsigned int *tsk_pinned;
- int old_count = 0;
- int old_idx = 0;
- int idx = 0;
-
- old_count = task_bp_pinned(cpu, bp, type);
- old_idx = old_count - 1;
- idx = old_idx + weight;
-
- /* tsk_pinned[n] is the number of tasks having n breakpoints */
- tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu);
- if (enable) {
- tsk_pinned[idx]++;
- if (old_count > 0)
- tsk_pinned[old_idx]--;
- } else {
- tsk_pinned[idx]--;
- if (old_count > 0)
- tsk_pinned[old_idx]++;
- }
+ /* tsk_pinned[n-1] is the number of tasks having n>0 breakpoints */
+ unsigned int *tsk_pinned = per_cpu(nr_task_bp_pinned[type], cpu);
+ int old_idx, new_idx;
+
+ old_idx = task_bp_pinned(cpu, bp, type) - 1;
+ if (enable)
+ new_idx = old_idx + weight;
+ else
+ new_idx = old_idx - weight;
+
+ if (old_idx >= 0)
+ tsk_pinned[old_idx]--;
+ if (new_idx >= 0)
+ tsk_pinned[new_idx]++;
}
/* Pinned counter task profiling */
}
/* Pinned counter task profiling */
-
- if (!enable)
- list_del(&bp->hw.bp_list);
-
if (cpu >= 0) {
toggle_bp_task_slot(bp, cpu, enable, type, weight);
} else {
if (cpu >= 0) {
toggle_bp_task_slot(bp, cpu, enable, type, weight);
} else {
if (enable)
list_add_tail(&bp->hw.bp_list, &bp_task_head);
if (enable)
list_add_tail(&bp->hw.bp_list, &bp_task_head);
+ else
+ list_del(&bp->hw.bp_list);