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[108.212.132.20]) by smtp.gmail.com with ESMTPSA id 586e51a60fabf-41c57bdf2b0sm8966606fac.7.2026.03.24.15.13.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Mar 2026 15:13:41 -0700 (PDT) From: Wesley Atwell To: linux-trace-kernel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, rostedt@goodmis.org, mhiramat@kernel.org, mark.rutland@arm.com, mathieu.desnoyers@efficios.com, tom.zanussi@linux.intel.com, Wesley Atwell Subject: [PATCH v4 1/2] tracing: Preserve repeated boot-time tracing parameters Date: Tue, 24 Mar 2026 16:13:25 -0600 Message-ID: <20260324221326.1395799-2-atwellwea@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260324221326.1395799-1-atwellwea@gmail.com> References: <20260324221326.1395799-1-atwellwea@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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=3D tokenizes its backing storage in place, so keep a running offset and only parse the newly appended chunk into bootup_triggers[]. This also lets Bootconfig array values work naturally when they expand to repeated param=3Dvalue entries. Signed-off-by: Wesley Atwell --- kernel/trace/ftrace.c | 12 ++++++++---- kernel/trace/trace.c | 31 ++++++++++++++++++++++++++++++- kernel/trace/trace.h | 2 ++ kernel/trace/trace_events.c | 26 +++++++++++++++++++++++--- kernel/trace/trace_kprobe.c | 3 ++- 5 files changed, 65 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 =3D 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=3D", set_ftrace_notrace); @@ -6849,7 +6850,8 @@ __setup("ftrace_notrace=3D", set_ftrace_notrace); static int __init set_ftrace_filter(char *str) { ftrace_filter_param =3D 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=3D", set_ftrace_filter); @@ -6861,14 +6863,16 @@ static int ftrace_graph_set_hash(struct ftrace_hash= *hash, char *buffer); =20 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=3D", set_graph_function); =20 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=3D", set_graph_notrace_function); diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index a626211ceb9a..1b1f6f9035c6 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -228,6 +228,34 @@ static int boot_instance_index; static char boot_snapshot_info[COMMAND_LINE_SIZE] __initdata; static int boot_snapshot_index; =20 +/* + * 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, + size_t size) +{ + size_t len, str_len; + + if (!buf[0]) { + strscpy(buf, str, size); + return; + } + + str_len =3D strlen(str); + if (!str_len) + return; + + len =3D strlen(buf); + if (len >=3D size - 1) + return; + if (str_len >=3D size - len - 1) + return; + + buf[len] =3D sep; + strscpy(buf + len + 1, str, size - len - 1); +} + static int __init set_cmdline_ftrace(char *str) { strscpy(bootup_tracer_buf, str, MAX_TRACER_SIZE); @@ -329,7 +357,8 @@ static char trace_boot_options_buf[MAX_TRACER_SIZE] __i= nitdata; =20 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=3D", set_trace_boot_options); diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index b8f3804586a0..64ce179d12dd 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); =20 extern void trace_set_ring_buffer_expanded(struct trace_array *tr); +void __init trace_append_boot_param(char *buf, const char *str, + char sep, size_t size); extern bool tracing_selftest_disabled; =20 #ifdef CONFIG_FTRACE_STARTUP_TEST diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 249d1cba72c0..5f72be33f2d1 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -3679,20 +3679,40 @@ static struct boot_triggers { } bootup_triggers[MAX_BOOT_TRIGGERS]; =20 static char bootup_trigger_buf[COMMAND_LINE_SIZE]; +static size_t bootup_trigger_buf_len; static int nr_boot_triggers; =20 static __init int setup_trace_triggers(char *str) { char *trigger; char *buf; + size_t start, str_len; int i; =20 - strscpy(bootup_trigger_buf, str, COMMAND_LINE_SIZE); + if (bootup_trigger_buf_len >=3D COMMAND_LINE_SIZE) + return 1; + + start =3D bootup_trigger_buf_len; + if (start && !*str) + return 1; + + str_len =3D strlen(str); + if (start && str_len >=3D COMMAND_LINE_SIZE - start) + return 1; + + /* + * trace_trigger=3D parsing tokenizes the backing storage in place. + * Copy each repeated parameter into fresh space and only parse that + * newly copied chunk here. + */ + trace_append_boot_param(bootup_trigger_buf + start, str, '\0', + COMMAND_LINE_SIZE - start); + bootup_trigger_buf_len +=3D strlen(bootup_trigger_buf + start) + 1; trace_set_ring_buffer_expanded(NULL); disable_tracing_selftest("running event triggers"); =20 - buf =3D bootup_trigger_buf; - for (i =3D 0; i < MAX_BOOT_TRIGGERS; i++) { + buf =3D bootup_trigger_buf + start; + for (i =3D nr_boot_triggers; i < MAX_BOOT_TRIGGERS; i++) { trigger =3D strsep(&buf, ","); if (!trigger) break; 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] __i= nitdata; 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[108.212.132.20]) by smtp.gmail.com with ESMTPSA id 586e51a60fabf-41c57bdf2b0sm8966606fac.7.2026.03.24.15.13.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Mar 2026 15:13:42 -0700 (PDT) From: Wesley Atwell To: linux-trace-kernel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, rostedt@goodmis.org, mhiramat@kernel.org, mark.rutland@arm.com, mathieu.desnoyers@efficios.com, tom.zanussi@linux.intel.com, Wesley Atwell Subject: [PATCH v4 2/2] tracing: Drain deferred trigger frees if kthread creation fails Date: Tue, 24 Mar 2026 16:13:26 -0600 Message-ID: <20260324221326.1395799-3-atwellwea@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260324221326.1395799-1-atwellwea@gmail.com> References: <20260324221326.1395799-1-atwellwea@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Boot-time trigger registration can fail before the trigger-data cleanup kthread exists. Deferring those frees until late init is fine, but the post-boot fallback must still drain the deferred list if kthread creation never succeeds. Otherwise, boot-deferred nodes can accumulate on trigger_data_free_list, later frees fall back to synchronously freeing only the current object, and the older queued entries are leaked forever. Keep the deferred boot-time behavior, but when kthread creation fails, drain the whole queued list synchronously. Do the same in the late-init drain path so queued entries are not stranded there either. Fixes: 61d445af0a7c ("tracing: Add bulk garbage collection of freeing event= _trigger_data") Signed-off-by: Wesley Atwell --- kernel/trace/trace_events_trigger.c | 79 ++++++++++++++++++++++++----- 1 file changed, 66 insertions(+), 13 deletions(-) diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_event= s_trigger.c index d5230b759a2d..655db2e82513 100644 --- a/kernel/trace/trace_events_trigger.c +++ b/kernel/trace/trace_events_trigger.c @@ -22,6 +22,39 @@ static struct task_struct *trigger_kthread; static struct llist_head trigger_data_free_list; static DEFINE_MUTEX(trigger_data_kthread_mutex); =20 +static int trigger_kthread_fn(void *ignore); + +static void trigger_create_kthread_locked(void) +{ + lockdep_assert_held(&trigger_data_kthread_mutex); + + if (!trigger_kthread) { + struct task_struct *kthread; + + kthread =3D kthread_create(trigger_kthread_fn, NULL, + "trigger_data_free"); + if (!IS_ERR(kthread)) + WRITE_ONCE(trigger_kthread, kthread); + } +} + +static void trigger_data_free_queued_locked(void) +{ + struct event_trigger_data *data, *tmp; + struct llist_node *llnodes; + + lockdep_assert_held(&trigger_data_kthread_mutex); + + llnodes =3D llist_del_all(&trigger_data_free_list); + if (!llnodes) + return; + + tracepoint_synchronize_unregister(); + + llist_for_each_entry_safe(data, tmp, llnodes, llist) + kfree(data); +} + /* Bulk garbage collection of event_trigger_data elements */ static int trigger_kthread_fn(void *ignore) { @@ -56,30 +89,50 @@ void trigger_data_free(struct event_trigger_data *data) if (data->cmd_ops->set_filter) data->cmd_ops->set_filter(NULL, data, NULL); =20 + /* + * Boot-time trigger registration can fail before kthread creation + * works. Keep the deferred-free semantics during boot and let late + * init start the kthread to drain the list. + */ + if (system_state =3D=3D SYSTEM_BOOTING && !trigger_kthread) { + llist_add(&data->llist, &trigger_data_free_list); + return; + } + if (unlikely(!trigger_kthread)) { guard(mutex)(&trigger_data_kthread_mutex); + + trigger_create_kthread_locked(); /* Check again after taking mutex */ if (!trigger_kthread) { - struct task_struct *kthread; - - kthread =3D kthread_create(trigger_kthread_fn, NULL, - "trigger_data_free"); - if (!IS_ERR(kthread)) - WRITE_ONCE(trigger_kthread, kthread); + llist_add(&data->llist, &trigger_data_free_list); + /* Drain the queued frees synchronously if creation failed. */ + trigger_data_free_queued_locked(); + return; } } =20 - if (!trigger_kthread) { - /* Do it the slow way */ - tracepoint_synchronize_unregister(); - kfree(data); - return; - } - llist_add(&data->llist, &trigger_data_free_list); wake_up_process(trigger_kthread); } =20 +static int __init trigger_data_free_init(void) +{ + guard(mutex)(&trigger_data_kthread_mutex); + + if (llist_empty(&trigger_data_free_list)) + return 0; + + trigger_create_kthread_locked(); + if (trigger_kthread) + wake_up_process(trigger_kthread); + else + trigger_data_free_queued_locked(); + + return 0; +} +late_initcall(trigger_data_free_init); + static inline void data_ops_trigger(struct event_trigger_data *data, struct trace_buffer *buffer, void *rec, struct ring_buffer_event *event) --=20 2.43.0