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[108.212.132.20]) by smtp.gmail.com with ESMTPSA id 00721157ae682-79cb7816752sm25431267b3.13.2026.03.29.11.43.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 29 Mar 2026 11:43:10 -0700 (PDT) From: Wesley Atwell To: Steven Rostedt , Masami Hiramatsu Cc: Mark Rutland , Mathieu Desnoyers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Wesley Atwell Subject: [PATCH v6] tracing: Preserve repeated boot-time tracing parameters Date: Sun, 29 Mar 2026 12:42:54 -0600 Message-ID: <20260329184254.1813273-1-atwellwea@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260328201842.1782806-1-atwellwea@gmail.com> References: <20260328201842.1782806-1-atwellwea@gmail.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Some tracing boot parameters already accept delimited value lists, but their __setup() handlers keep only the last instance seen at boot. Make repeated instances append to the same boot-time buffer in the format each parser already consumes. Use a shared trace_append_boot_param() helper for the ftrace filters, trace_options, and kprobe_event boot parameters. trace_trigger= still tokenizes a temporary parse buffer in place, but now copies each parsed event/trigger pair into boot-time storage so repeated instances do not overwrite earlier ones. This also lets Bootconfig array values work naturally when they expand to repeated param=value entries. Before this change, only the last instance from each repeated parameter survived boot. Signed-off-by: Wesley Atwell --- Changes since v5: https://lore.kernel.org/all/20260328201842.1782806-1-atwellwea@gmail.com/ - add the separator accounting comment in trace_append_boot_param() - keep the existing trace_trigger= temporary buffer and copy each parsed event/trigger pair into boot-time storage instead of tracking a running offset inside that buffer kernel/trace/ftrace.c | 12 ++++++++---- kernel/trace/trace.c | 30 +++++++++++++++++++++++++++++- kernel/trace/trace.h | 2 ++ kernel/trace/trace_events.c | 24 +++++++++++++++++++++--- kernel/trace/trace_kprobe.c | 3 ++- 5 files changed, 62 insertions(+), 9 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 413310912609..8bd3dd1d549c 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -6841,7 +6841,8 @@ bool ftrace_filter_param __initdata; static int __init set_ftrace_notrace(char *str) { ftrace_filter_param = true; - strscpy(ftrace_notrace_buf, str, FTRACE_FILTER_SIZE); + trace_append_boot_param(ftrace_notrace_buf, str, ',', + FTRACE_FILTER_SIZE); return 1; } __setup("ftrace_notrace=", set_ftrace_notrace); @@ -6849,7 +6850,8 @@ __setup("ftrace_notrace=", set_ftrace_notrace); static int __init set_ftrace_filter(char *str) { ftrace_filter_param = true; - strscpy(ftrace_filter_buf, str, FTRACE_FILTER_SIZE); + trace_append_boot_param(ftrace_filter_buf, str, ',', + FTRACE_FILTER_SIZE); return 1; } __setup("ftrace_filter=", set_ftrace_filter); @@ -6861,14 +6863,16 @@ static int ftrace_graph_set_hash(struct ftrace_hash *hash, char *buffer); static int __init set_graph_function(char *str) { - strscpy(ftrace_graph_buf, str, FTRACE_FILTER_SIZE); + trace_append_boot_param(ftrace_graph_buf, str, ',', + FTRACE_FILTER_SIZE); return 1; } __setup("ftrace_graph_filter=", set_graph_function); static int __init set_graph_notrace_function(char *str) { - strscpy(ftrace_graph_notrace_buf, str, FTRACE_FILTER_SIZE); + trace_append_boot_param(ftrace_graph_notrace_buf, str, ',', + FTRACE_FILTER_SIZE); return 1; } __setup("ftrace_graph_notrace=", set_graph_notrace_function); diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index a626211ceb9a..2fbfcb506b24 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -228,6 +228,33 @@ static int boot_instance_index; static char boot_snapshot_info[COMMAND_LINE_SIZE] __initdata; static int boot_snapshot_index; +/* + * Repeated boot parameters, including Bootconfig array expansions, need + * to stay in the delimiter form that the existing parser consumes. + */ +void __init trace_append_boot_param(char *buf, const char *str, char sep, + int size) +{ + int len, needed, str_len; + + if (!*str) + return; + + len = strlen(buf); + str_len = strlen(str); + needed = len + str_len + 1; + /* For continuation, account for the separator. */ + if (len) + needed++; + if (needed > size) + return; + + if (len) + buf[len++] = sep; + + strscpy(buf + len, str, size - len); +} + static int __init set_cmdline_ftrace(char *str) { strscpy(bootup_tracer_buf, str, MAX_TRACER_SIZE); @@ -329,7 +356,8 @@ static char trace_boot_options_buf[MAX_TRACER_SIZE] __initdata; static int __init set_trace_boot_options(char *str) { - strscpy(trace_boot_options_buf, str, MAX_TRACER_SIZE); + trace_append_boot_param(trace_boot_options_buf, str, ',', + MAX_TRACER_SIZE); return 1; } __setup("trace_options=", set_trace_boot_options); diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index b8f3804586a0..237a0417de1c 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -863,6 +863,8 @@ extern int DYN_FTRACE_TEST_NAME(void); extern int DYN_FTRACE_TEST_NAME2(void); extern void trace_set_ring_buffer_expanded(struct trace_array *tr); +void __init trace_append_boot_param(char *buf, const char *str, + char sep, int size); extern bool tracing_selftest_disabled; #ifdef CONFIG_FTRACE_STARTUP_TEST diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 249d1cba72c0..1c4a4a46169e 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include #include @@ -3674,7 +3675,7 @@ trace_create_new_event(struct trace_event_call *call, #define MAX_BOOT_TRIGGERS 32 static struct boot_triggers { - const char *event; + char *event; char *trigger; } bootup_triggers[MAX_BOOT_TRIGGERS]; @@ -3683,6 +3684,7 @@ static int nr_boot_triggers; static __init int setup_trace_triggers(char *str) { + char *event; char *trigger; char *buf; int i; @@ -3692,14 +3694,30 @@ static __init int setup_trace_triggers(char *str) disable_tracing_selftest("running event triggers"); buf = bootup_trigger_buf; - for (i = 0; i < MAX_BOOT_TRIGGERS; i++) { + for (i = nr_boot_triggers; i < MAX_BOOT_TRIGGERS; i++) { trigger = strsep(&buf, ","); if (!trigger) break; - bootup_triggers[i].event = strsep(&trigger, "."); + event = strsep(&trigger, "."); bootup_triggers[i].trigger = trigger; if (!bootup_triggers[i].trigger) break; + + /* + * Keep each parsed trigger outside the temporary setup + * buffer so repeated trace_trigger= entries do not + * overwrite earlier ones. + */ + bootup_triggers[i].event = + memblock_alloc_or_panic(strlen(event) + 1, + SMP_CACHE_BYTES); + strscpy(bootup_triggers[i].event, event, + strlen(event) + 1); + bootup_triggers[i].trigger = + memblock_alloc_or_panic(strlen(trigger) + 1, + SMP_CACHE_BYTES); + strscpy(bootup_triggers[i].trigger, trigger, + strlen(trigger) + 1); } nr_boot_triggers = i; diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index a5dbb72528e0..e9f1c55aea64 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -31,7 +31,8 @@ static char kprobe_boot_events_buf[COMMAND_LINE_SIZE] __initdata; static int __init set_kprobe_boot_events(char *str) { - strscpy(kprobe_boot_events_buf, str, COMMAND_LINE_SIZE); + trace_append_boot_param(kprobe_boot_events_buf, str, ';', + COMMAND_LINE_SIZE); disable_tracing_selftest("running kprobe events"); return 1; -- 2.43.0