ring-buffer: Move disabled check into preempt disable section

[safe/jmp/linux-2.6] / kernel / hw_breakpoint.c

diff --git a/kernel/hw_breakpoint.c b/kernel/hw_breakpoint.c
index c030ae6..967e661 100644 (file)
--- a/kernel/hw_breakpoint.c
+++ b/kernel/hw_breakpoint.c
@@ -243,38 +243,70 @@ static void toggle_bp_slot(struct perf_event *bp, bool enable)
  *       ((per_cpu(nr_bp_flexible, *) > 1) + max(per_cpu(nr_cpu_bp_pinned, *))
  *            + max(per_cpu(nr_task_bp_pinned, *))) < HBP_NUM
  */
-int reserve_bp_slot(struct perf_event *bp)
+static int __reserve_bp_slot(struct perf_event *bp)
 {
        struct bp_busy_slots slots = {0};
-       int ret = 0;
-
-       mutex_lock(&nr_bp_mutex);
 
        fetch_bp_busy_slots(&slots, bp);
 
        /* Flexible counters need to keep at least one slot */
-       if (slots.pinned + (!!slots.flexible) == HBP_NUM) {
-               ret = -ENOSPC;
-               goto end;
-       }
+       if (slots.pinned + (!!slots.flexible) == HBP_NUM)
+               return -ENOSPC;
 
        toggle_bp_slot(bp, true);
 
-end:
+       return 0;
+}
+
+int reserve_bp_slot(struct perf_event *bp)
+{
+       int ret;
+
+       mutex_lock(&nr_bp_mutex);
+
+       ret = __reserve_bp_slot(bp);
+
        mutex_unlock(&nr_bp_mutex);
 
        return ret;
 }
 
+static void __release_bp_slot(struct perf_event *bp)
+{
+       toggle_bp_slot(bp, false);
+}
+
 void release_bp_slot(struct perf_event *bp)
 {
        mutex_lock(&nr_bp_mutex);
 
-       toggle_bp_slot(bp, false);
+       __release_bp_slot(bp);
 
        mutex_unlock(&nr_bp_mutex);
 }
 
+/*
+ * Allow the kernel debugger to reserve breakpoint slots without
+ * taking a lock using the dbg_* variant of for the reserve and
+ * release breakpoint slots.
+ */
+int dbg_reserve_bp_slot(struct perf_event *bp)
+{
+       if (mutex_is_locked(&nr_bp_mutex))
+               return -1;
+
+       return __reserve_bp_slot(bp);
+}
+
+int dbg_release_bp_slot(struct perf_event *bp)
+{
+       if (mutex_is_locked(&nr_bp_mutex))
+               return -1;
+
+       __release_bp_slot(bp);
+
+       return 0;
+}
 
 int register_perf_hw_breakpoint(struct perf_event *bp)
 {
@@ -328,8 +360,8 @@ EXPORT_SYMBOL_GPL(register_user_hw_breakpoint);
 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 old_len = bp->attr.bp_len;
        int err = 0;
 
        perf_event_disable(bp);