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([2001:fb1:db:5c33:7066:708a:3018:7aec]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-cabc7b2aa4bsm2033582a12.10.2026.07.12.21.57.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 12 Jul 2026 21:57:53 -0700 (PDT) Message-ID: <79f36674-5a35-4aaf-b5b1-bc6189c222ad@gmail.com> Date: Mon, 13 Jul 2026 11:57:46 +0700 Precedence: bulk X-Mailing-List: linux-kernel-mentees@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] tracing: Use seq_buf for string concatenation To: Steven Rostedt Cc: mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, linux-kernel-mentees@lists.linux.dev, shuah@kernel.org, skhan@linuxfoundation.org, me@brighamcampbell.com, jkoolstra@xs4all.nl References: <20260622094623.18469-1-woradorn.laon@gmail.com> <20260629143947.2216574e@robin> Content-Language: en-US From: Woradorn Laodhanadhaworn In-Reply-To: <20260629143947.2216574e@robin> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 30/6/2569 BE 01:39, Steven Rostedt wrote: > On Mon, 22 Jun 2026 16:46:23 +0700 > Woradorn Laodhanadhaworn wrote: > >> >> #include >> #include >> @@ -4500,14 +4501,20 @@ static void __add_event_to_tracers(struct trace_event_call *call) >> extern struct trace_event_call *__start_ftrace_events[]; >> extern struct trace_event_call *__stop_ftrace_events[]; >> >> -static char bootup_event_buf[COMMAND_LINE_SIZE] __initdata; > > Keep the above string and just assign it. > >> +static struct seq_buf bootup_event_buf __initdata = { >> + .buffer = (char[COMMAND_LINE_SIZE]) {}, >> + .size = COMMAND_LINE_SIZE, >> +}; > > static struct seq_buf bootup_event_seq __initdata = { > .buffer = bootup_event_buf; > .size = sizeof(bootup_event_buf); > }; > >> >> static __init int setup_trace_event(char *str) >> { >> - if (bootup_event_buf[0] != '\0') >> - strlcat(bootup_event_buf, ",", COMMAND_LINE_SIZE); >> + if (seq_buf_used(&bootup_event_buf) > 0) >> + seq_buf_puts(&bootup_event_buf, ","); >> + >> + seq_buf_puts(&bootup_event_buf, str); >> >> - strlcat(bootup_event_buf, str, COMMAND_LINE_SIZE); >> + if (seq_buf_has_overflowed(&bootup_event_buf)) >> + return -ENOMEM; >> >> trace_set_ring_buffer_expanded(NULL); >> disable_tracing_selftest("running event tracing"); >> @@ -4766,7 +4773,7 @@ static __init int event_trace_enable(void) >> */ >> __trace_early_add_events(tr); >> >> - early_enable_events(tr, bootup_event_buf, false); >> + early_enable_events(tr, (char *)seq_buf_str(&bootup_event_buf), false); > > The above then would be: > > seq_buf_str(&bootup_event_seq); > early_enable_events(tr, bootup_event_buf, false); > > Don't typecast a const char* to non const. > >> >> trace_printk_start_comm(); >> >> @@ -4794,7 +4801,7 @@ static __init int event_trace_enable_again(void) >> if (!tr) >> return -ENODEV; >> >> - early_enable_events(tr, bootup_event_buf, true); >> + early_enable_events(tr, (char *)seq_buf_str(&bootup_event_buf), true); > > Same here. > > -- Steve > >> >> return 0; >> } > Thank you, Steven, for your review. I've sent v4: https://lore.kernel.org/all/20260713045249.69942-1-woradorn.laon@gmail.com Thanks, Woradorn