diff mbox series

[v4,11/39] dyndbg: don't close trace instance when in use

Message ID 20240210235009.2405808-12-ukaszb@chromium.org
State New
Headers
Series dyndbg: add support for writing debug logs to trace |

Commit Message

Łukasz Bartosik Feb. 10, 2024, 11:49 p.m. UTC 
  Don't allow trace instance to be closed when it
is still being used by at least one callsite.

Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
---
 lib/dynamic_debug.c | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)
diff mbox series

Patch

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index d0d1057911e8..6668f265f2c3 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -81,6 +81,7 @@  struct flag_settings {
 struct dd_private_tracebuf {
 	const char *name;
 	struct trace_array *arr;
+	int use_cnt;
 };
 
 /*
@@ -279,6 +280,7 @@  static int handle_trace_open_cmd(const char *arg)
 		goto end;
 	}
 
+	buf->use_cnt = 0;
 	set_bit(idx, trc_tbl.bmap);
 	v3pr_info("opened trace instance idx=%d, name=%s\n", idx, arg);
 end:
@@ -301,6 +303,14 @@  static int handle_trace_close_cmd(const char *arg)
 
 	buf = &trc_tbl.buf[idx];
 
+	WARN_ON(buf->use_cnt < 0);
+	if (buf->use_cnt) {
+		pr_err("trace instance is being used name=%s, use_cnt=%d\n",
+		       buf->name, buf->use_cnt);
+		ret = -EBUSY;
+		goto end;
+	}
+
 	trace_array_put(buf->arr);
 	/*
 	 * don't destroy trace instance but let user do it manually
@@ -321,6 +331,22 @@  static int handle_trace_close_cmd(const char *arg)
 	return ret;
 }
 
+static
+void update_tr_dst(const struct _ddebug *desc, const struct dd_ctrl *nctrl)
+{
+	int odst = get_trace_dst(desc);
+	int ndst = nctrl->trace_dst;
+
+	if (odst == ndst)
+		return;
+
+	if (odst)
+		trc_tbl.buf[odst].use_cnt--;
+
+	if (ndst)
+		trc_tbl.buf[ndst].use_cnt++;
+}
+
 static int ddebug_parse_cmd(char *words[], int nwords)
 {
 	if (nwords != 1)
@@ -447,6 +473,7 @@  static int ddebug_change(const struct ddebug_query *query,
 				  dt->mod_name, dp->function,
 				  ddebug_describe_flags(get_flags(dp), &fbuf),
 				  ddebug_describe_flags(nctrl.flags, &nbuf));
+			update_tr_dst(dp, &nctrl);
 			set_ctrl(dp, &nctrl);
 		}
 	}
@@ -1628,6 +1655,14 @@  int ddebug_dyndbg_module_param_cb(char *param, char *val, const char *module)
 
 static void ddebug_table_free(struct ddebug_table *dt)
 {
+	int dst, i;
+
+	for (i = 0; i < dt->num_ddebugs; i++) {
+		dst = get_trace_dst(&dt->ddebugs[i]);
+		if (dst)
+			trc_tbl.buf[dst].use_cnt--;
+	}
+
 	list_del_init(&dt->link);
 	kfree(dt);
 }