linux-kernel - [PATCH v5 07/33] dyndbg: let query-modname override actual module name

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Date:   Fri,  5 Aug 2022 15:53:29 -0600
From:   Jim Cromie <jim.cromie@...il.com>
To:     linux-kernel@...r.kernel.org, jbaron@...mai.com,
        gregkh@...uxfoundation.org, dri-devel@...ts.freedesktop.org,
        amd-gfx@...ts.freedesktop.org, intel-gvt-dev@...ts.freedesktop.org,
        intel-gfx@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org, linux-arm-msm@...r.kernel.org
Cc:     daniel.vetter@...ll.ch, seanpaul@...omium.org, robdclark@...il.com,
        Jim Cromie <jim.cromie@...il.com>
Subject: [PATCH v5 07/33] dyndbg: let query-modname override actual module name

dyndbg's control-parser: ddebug_parse_query(), requires that search
terms: module, func, file, lineno, are used only once in a query; a
thing cannot be named both foo and bar.

The cited commit added an overriding module modname, taken from the
module loader, which is authoritative.  So it set query.module 1st,
which disallowed its use in the query-string.

But now, its useful to allow a module-load to enable classes across a
whole (or part of) a subsystem at once.

  # enable (dynamic-debug in) drm only
  modprobe drm dyndbg="class DRM_UT_CORE +p"

  # get drm_helper too
  modprobe drm dyndbg="class DRM_UT_CORE module drm* +p"

  # get everything that knows DRM_UT_CORE
  modprobe drm dyndbg="class DRM_UT_CORE module * +p"

  # also for boot-args:
  drm.dyndbg="class DRM_UT_CORE module * +p"

So convert the override into a default, by filling it only when/after
the query-string omitted the module.

NB: the query class FOO handling is forthcoming.

Fixes: 8e59b5cfb9a6 dynamic_debug: add modname arg to exec_query callchain
Signed-off-by: Jim Cromie <jim.cromie@...il.com>
Acked-by: Jason Baron <jbaron@...mai.com>
---
 lib/dynamic_debug.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index e5cbe603000c..5a849716220a 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -385,10 +385,6 @@ static int ddebug_parse_query(char *words[], int nwords,
 		return -EINVAL;
 	}
 
-	if (modname)
-		/* support $modname.dyndbg=<multiple queries> */
-		query->module = modname;
-
 	for (i = 0; i < nwords; i += 2) {
 		char *keyword = words[i];
 		char *arg = words[i+1];
@@ -429,6 +425,13 @@ static int ddebug_parse_query(char *words[], int nwords,
 		if (rc)
 			return rc;
 	}
+	if (!query->module && modname)
+		/*
+		 * support $modname.dyndbg=<multiple queries>, when
+		 * not given in the query itself
+		 */
+		query->module = modname;
+
 	vpr_info_dq(query, "parsed");
 	return 0;
 }
-- 
2.37.1