linux-kernel - [PATCH 19/20] function_graph: Use for_each_set_bit() in __ftrace_return_to

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Message-ID: <20240525023744.231570357@goodmis.org>
Date: Fri, 24 May 2024 22:37:11 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: linux-kernel@...r.kernel.org,
 linux-trace-kernel@...r.kernel.org
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
 Mark Rutland <mark.rutland@....com>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Alexei Starovoitov <alexei.starovoitov@...il.com>,
 Florent Revest <revest@...omium.org>,
 Martin KaFai Lau <martin.lau@...ux.dev>,
 bpf <bpf@...r.kernel.org>,
 Sven Schnelle <svens@...ux.ibm.com>,
 Alexei Starovoitov <ast@...nel.org>,
 Jiri Olsa <jolsa@...nel.org>,
 Arnaldo Carvalho de Melo <acme@...nel.org>,
 Daniel Borkmann <daniel@...earbox.net>,
 Alan Maguire <alan.maguire@...cle.com>,
 Peter Zijlstra <peterz@...radead.org>,
 Thomas Gleixner <tglx@...utronix.de>,
 Guo Ren <guoren@...nel.org>
Subject: [PATCH 19/20] function_graph: Use for_each_set_bit() in
 __ftrace_return_to_handler()

From: "Steven Rostedt (Google)" <rostedt@...dmis.org>

Instead of iterating through the entire fgraph_array[] and seeing if one
of the bitmap bits are set to know to call the array's retfunc() function,
use for_each_set_bit() on the bitmap itself. This will only iterate for
the number of set bits.

Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
 kernel/trace/fgraph.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 4d503b3e45ad..5e8e13ffcfb6 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -827,11 +827,10 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
 #endif
 
 	bitmap = get_bitmap_bits(current, offset);
-	for (i = 0; i < FGRAPH_ARRAY_SIZE; i++) {
+
+	for_each_set_bit(i, &bitmap, sizeof(bitmap) * BITS_PER_BYTE) {
 		struct fgraph_ops *gops = fgraph_array[i];
 
-		if (!(bitmap & BIT(i)))
-			continue;
 		if (gops == &fgraph_stub)
 			continue;
 
-- 
2.43.0