linux-kernel - [PATCH v2 06/15] dyndbg: use __get_str_strip

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Message-ID: <20231130234048.157509-7-lb@semihalf.com>
Date:   Fri,  1 Dec 2023 00:40:39 +0100
From:   Łukasz Bartosik <lb@...ihalf.com>
To:     Jason Baron <jbaron@...mai.com>, Jim Cromie <jim.cromie@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>,
        Douglas Anderson <dianders@...omium.org>
Cc:     Guenter Roeck <groeck@...gle.com>,
        Yaniv Tzoreff <yanivt@...gle.com>,
        Benson Leung <bleung@...gle.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Vincent Whitchurch <vincent.whitchurch@...s.com>,
        Pekka Paalanen <ppaalanen@...il.com>,
        Sean Paul <seanpaul@...omium.org>,
        Daniel Vetter <daniel@...ll.ch>, linux-kernel@...r.kernel.org,
        upstream@...ihalf.com
Subject: [PATCH v2 06/15] dyndbg: use __get_str_strip_nl in prdbg and devdbg

From: Jim Cromie <jim.cromie@...il.com>

Recently added dyndbg events: prdbg, devdbg have code to strip the
trailing newline, if it's there.  Instead of removing the newline
in TP_fast_assign use __get_str_strip_nl macro in TP_printk. Advantage
of such an approach is that the removal is done on the read side (slow
path). The change removes also passing of debug message length to prdbg
and devdbg events.

This use is slightly premature/overkill, since some pr_debugs do not
have the expected trailing newline.  While those lacks are arguably
bugs, this doesn't fix them.

Signed-off-by: Jim Cromie <jim.cromie@...il.com>
Signed-off-by: Łukasz Bartosik <lb@...ihalf.com>
---
 include/trace/events/dyndbg.h | 27 +++++++++------------------
 lib/dynamic_debug.c           |  7 +++----
 2 files changed, 12 insertions(+), 22 deletions(-)

diff --git a/include/trace/events/dyndbg.h b/include/trace/events/dyndbg.h
index 647c30206a7d..ffd21480cd9d 100644
--- a/include/trace/events/dyndbg.h
+++ b/include/trace/events/dyndbg.h
@@ -15,46 +15,37 @@
 DECLARE_EVENT_CLASS(dyndbg_template,
 
 	TP_PROTO(const struct _ddebug *desc, const struct device *dev,
-		 const char *msg, size_t len),
+		 const char *msg),
 
-	TP_ARGS(desc, dev, msg, len),
+	TP_ARGS(desc, dev, msg),
 
 	TP_STRUCT__entry(
-		__dynamic_array(char, s, len+1)
+		__string(s, msg)
 	    ),
 
 	TP_fast_assign(
-		/*
-		 * Each trace entry is printed in a new line.
-		 * If the msg finishes with '\n', cut it off
-		 * to avoid blank lines in the trace.
-		 */
-		if (len > 0 && (msg[len-1] == '\n'))
-			len -= 1;
-
-		memcpy(__get_str(s), msg, len);
-		__get_str(s)[len] = 0;
+		__assign_str(s, msg);
 	    ),
 
-	TP_printk("%s", __get_str(s))
+	TP_printk("%s", __get_str_strip_nl(s))
 );
 
 /* captures pr_debug() callsites */
 DEFINE_EVENT(dyndbg_template, prdbg,
 
 	TP_PROTO(const struct _ddebug *desc, const struct device *dev,
-		 const char *msg, size_t len),
+		 const char *msg),
 
-	TP_ARGS(desc, dev, msg, len)
+	TP_ARGS(desc, dev, msg)
 );
 
 /* captures dev_dbg() callsites */
 DEFINE_EVENT(dyndbg_template, devdbg,
 
 	TP_PROTO(const struct _ddebug *desc, const struct device *dev,
-		 const char *msg, size_t len),
+		 const char *msg),
 
-	TP_ARGS(desc, dev, msg, len)
+	TP_ARGS(desc, dev, msg)
 );
 
 #endif /* _TRACE_DYNDBG_H */
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index fcc7c5631b53..9682277f3909 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -886,7 +886,6 @@ static void ddebug_trace(struct _ddebug *desc, const struct device *dev,
 {
 	struct ddebug_trace_buf *buf;
 	int bufidx;
-	int len;
 
 	preempt_disable_notrace();
 
@@ -900,12 +899,12 @@ static void ddebug_trace(struct _ddebug *desc, const struct device *dev,
 
 	buf = this_cpu_ptr(ddebug_trace_bufs.bufs) + bufidx;
 
-	len = vscnprintf(buf->buf, sizeof(buf->buf), fmt, args);
+	vscnprintf(buf->buf, sizeof(buf->buf), fmt, args);
 
 	if (!dev)
-		trace_prdbg(desc, NULL, buf->buf, len);
+		trace_prdbg(desc, NULL, buf->buf);
 	else
-		trace_devdbg(desc, dev, buf->buf, len);
+		trace_devdbg(desc, dev, buf->buf);
 
 out:
 	/* As above. */
-- 
2.43.0.rc2.451.g8631bc7472-goog