linux-kernel - [PATCH v6 2/4] fprobe: Support comma-separated filters in register

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Message-ID: <20260205135842.20517-3-seokwoo.chung130@gmail.com>
Date: Thu,  5 Feb 2026 08:58:40 -0500
From: "Seokwoo Chung (Ryan)" <seokwoo.chung130@...il.com>
To: mhiramat@...nel.org
Cc: rostedt@...dmis.org,
	corbet@....net,
	shuah@...nel.org,
	mathieu.desnoyers@...icios.com,
	linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org,
	linux-kselftest@...r.kernel.org,
	"Seokwoo Chung (Ryan)" <seokwoo.chung130@...il.com>
Subject: [PATCH v6 2/4] fprobe: Support comma-separated filters in register_fprobe()

register_fprobe() passes its filter and notfilter strings directly to
glob_match(), which only understands shell-style globs (*, ?, [...]).
Comma-separated symbol lists such as "vfs_read,vfs_open" never match
any symbol because no kernel symbol contains a comma.

Add glob_match_comma_list() that splits the filter on commas and
checks each entry individually with glob_match().  The existing
single-pattern fast path is preserved (no commas means the loop
executes exactly once).

This is required by the comma-separated fprobe list syntax introduced
in the preceding patch; without it, enabling a list-mode fprobe event
fails with "Could not enable event".

Signed-off-by: Seokwoo Chung (Ryan) <seokwoo.chung130@...il.com>
---
 kernel/trace/fprobe.c | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index 1188eefef07c..2acd24b80d04 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -672,12 +672,38 @@ struct filter_match_data {
 	struct module **mods;
 };
 
+/*
+ * Check if @name matches any comma-separated glob pattern in @list.
+ * If @list contains no commas, this is equivalent to glob_match().
+ */
+static bool glob_match_comma_list(const char *list, const char *name)
+{
+	const char *cur = list;
+
+	while (*cur) {
+		const char *sep = strchr(cur, ',');
+		int len = sep ? sep - cur : strlen(cur);
+		char pat[KSYM_NAME_LEN];
+
+		if (len > 0 && len < KSYM_NAME_LEN) {
+			memcpy(pat, cur, len);
+			pat[len] = '\0';
+			if (glob_match(pat, name))
+				return true;
+		}
+		if (!sep)
+			break;
+		cur = sep + 1;
+	}
+	return false;
+}
+
 static int filter_match_callback(void *data, const char *name, unsigned long addr)
 {
 	struct filter_match_data *match = data;
 
-	if (!glob_match(match->filter, name) ||
-	    (match->notfilter && glob_match(match->notfilter, name)))
+	if (!glob_match_comma_list(match->filter, name) ||
+	    (match->notfilter && glob_match_comma_list(match->notfilter, name)))
 		return 0;
 
 	if (!ftrace_location(addr))
-- 
2.43.0