From: Yichun Zhang (agentzh) <yichun@openresty.com>
Date: Wed, 15 May 2024 18:48:06 +0000 (-0700)
Subject: PR31740: use of @hist_log or @hist_linear would lead to bad results in stat ops like... 
X-Git-Url: https://sourceware.org/git/?a=commitdiff_plain;h=289609c9b75587d295c74cb59b9b6038ce9c396e;p=systemtap.git

PR31740: use of @hist_log or @hist_linear would lead to bad results in stat ops like @variance()

The fields bit_shift and stat_ops of pmap were never initialized
properly in such cases.
---

diff --git a/runtime/pmap-gen.c b/runtime/pmap-gen.c
index b1c910036..a1dbf6e03 100644
--- a/runtime/pmap-gen.c
+++ b/runtime/pmap-gen.c
@@ -207,10 +207,6 @@ KEYSYM(_stp_pmap_new) (int first_arg, ...)
 	case HIST_NONE:
 		pmap = _stp_pmap_new_hstat (max_entries, wrap,
 		                            sizeof(struct KEYSYM(map_node)));
-		if (pmap) {
-			pmap->bit_shift = bit_shift;
-			pmap->stat_ops = stat_ops;
-		}
 		break;
 	case HIST_LOG:
 		pmap = _stp_pmap_new_hstat_log (max_entries, wrap,
@@ -226,6 +222,10 @@ KEYSYM(_stp_pmap_new) (int first_arg, ...)
 		pmap = NULL;
 	}
 
+        if (pmap) {
+		pmap->bit_shift = bit_shift;
+		pmap->stat_ops = stat_ops;
+        }
 
 	return pmap;
 }
diff --git a/testsuite/systemtap.maps/PR31740.exp b/testsuite/systemtap.maps/PR31740.exp
new file mode 100644
index 000000000..e840e7ee3
--- /dev/null
+++ b/testsuite/systemtap.maps/PR31740.exp
@@ -0,0 +1,41 @@
+set test "PR31740"
+set testpath "$srcdir/$subdir"
+set work_dir [pwd]
+
+if {! [installtest_p]} { untested $test; return }
+
+# --- TEST 1 ---
+
+set subtest1 "TEST 1: PR31740: hist_log"
+foreach runtime [get_runtime_list] {
+    if {$runtime eq ""} {
+        set runtime "kernel"
+    }
+    set test_name "$test: $subtest1 ($runtime)"
+    set cmd "stap --runtime=$runtime '$srcdir/$subdir/${test}_1.stp'"
+    set exit_code [run_cmd_2way $cmd out stderr]
+    set exp_out "variance = 1\n"
+    is "${test_name}: stdout" $out $exp_out
+    is "${test_name}: exit code" $exit_code 0
+    if {$stderr ne ""} {
+        send_log "stderr:\n$stderr"
+    }
+}
+
+# --- TEST 2 ---
+
+set subtest2 "TEST 2: PR31740: hist_linear"
+foreach runtime [get_runtime_list] {
+    if {$runtime eq ""} {
+        set runtime "kernel"
+    }
+    set test_name "$test: $subtest2 ($runtime)"
+    set cmd "stap --runtime=$runtime '$srcdir/$subdir/${test}_2.stp'"
+    set exit_code [run_cmd_2way $cmd out stderr]
+    set exp_out "variance = 1\n"
+    is "${test_name}: stdout" $out $exp_out
+    is "${test_name}: exit code" $exit_code 0
+    if {$stderr ne ""} {
+        send_log "stderr:\n$stderr"
+    }
+}
diff --git a/testsuite/systemtap.maps/PR31740_1.stp b/testsuite/systemtap.maps/PR31740_1.stp
new file mode 100644
index 000000000..33951fc60
--- /dev/null
+++ b/testsuite/systemtap.maps/PR31740_1.stp
@@ -0,0 +1,12 @@
+global stats;
+
+probe oneshot {
+    stats["k"] <<< 1;
+    stats["k"] <<< 2;
+    stats["k"] <<< 3;
+    printf("variance = %d\n", @variance(stats["k"], 7));
+}
+
+probe never {
+    print(@hist_log(stats["k"]));
+}
diff --git a/testsuite/systemtap.maps/PR31740_2.stp b/testsuite/systemtap.maps/PR31740_2.stp
new file mode 100644
index 000000000..5469b163f
--- /dev/null
+++ b/testsuite/systemtap.maps/PR31740_2.stp
@@ -0,0 +1,12 @@
+global stats;
+
+probe oneshot {
+    stats["k"] <<< 1;
+    stats["k"] <<< 2;
+    stats["k"] <<< 3;
+    printf("variance = %d\n", @variance(stats["k"], 7));
+}
+
+probe never {
+    print(@hist_linear(stats["k"], 0, 4, 1));
+}