[PATCH] blkparse: don't let ->cur_depth go below zero

This can happen if we miss traces, so check for it.

diff --git a/blkparse.c b/blkparse.c
index 8a9f6d70a2925c476ee0311358a051122425ec4e..7da67a609a7891e3118db33e0ae91509e8954b54 100644 (file)
--- a/blkparse.c
+++ b/blkparse.c
@@ -1250,7 +1250,12 @@ static void dump_trace_fs(struct blk_io_trace *t, struct per_dev_info *pdi,
                        log_generic(pci, t, "S");
                        break;
                case __BLK_TA_REQUEUE:
-                       pdi->cur_depth[w]--;
+                       /*
+                        * can happen if we miss traces, don't let it go
+                        * below zero
+                        */
+                       if (pdi->cur_depth[w])
+                               pdi->cur_depth[w]--;
                        account_requeue(t, pci, w);
                        log_queue(pci, t, "R");
                        break;
@@ -1262,7 +1267,8 @@ static void dump_trace_fs(struct blk_io_trace *t, struct per_dev_info *pdi,
                        log_issue(pdi, pci, t, "D");
                        break;
                case __BLK_TA_COMPLETE:
-                       pdi->cur_depth[w]--;
+                       if (pdi->cur_depth[w])
+                               pdi->cur_depth[w]--;
                        account_c(t, pci, w, t->bytes);
                        log_complete(pdi, pci, t, "C");
                        break;