From nobody Sun Feb 8 01:30:36 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 21A17C001DF for ; Sat, 29 Jul 2023 18:34:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229830AbjG2Se2 (ORCPT ); Sat, 29 Jul 2023 14:34:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43094 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229610AbjG2SeY (ORCPT ); Sat, 29 Jul 2023 14:34:24 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 606EF30FC for ; Sat, 29 Jul 2023 11:34:23 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id D6D40608C3 for ; Sat, 29 Jul 2023 18:34:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 39C4FC433C8; Sat, 29 Jul 2023 18:34:22 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.96) (envelope-from ) id 1qPolh-0035IS-0l; Sat, 29 Jul 2023 14:34:21 -0400 Message-ID: <20230729183421.051522156@goodmis.org> User-Agent: quilt/0.66 Date: Sat, 29 Jul 2023 14:33:34 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Andrew Morton , , Zheng Yejian Subject: [for-linus][PATCH 1/7] ring-buffer: Fix wrong stat of cpu_buffer->read References: <20230729183333.357029101@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Zheng Yejian When pages are removed in rb_remove_pages(), 'cpu_buffer->read' is set to 0 in order to make sure any read iterators reset themselves. However, this will mess 'entries' stating, see following steps: # cd /sys/kernel/tracing/ # 1. Enlarge ring buffer prepare for later reducing: # echo 20 > per_cpu/cpu0/buffer_size_kb # 2. Write a log into ring buffer of cpu0: # taskset -c 0 echo "hello1" > trace_marker # 3. Read the log: # cat per_cpu/cpu0/trace_pipe <...>-332 [000] ..... 62.406844: tracing_mark_write: hello1 # 4. Stop reading and see the stats, now 0 entries, and 1 event readed: # cat per_cpu/cpu0/stats entries: 0 [...] read events: 1 # 5. Reduce the ring buffer # echo 7 > per_cpu/cpu0/buffer_size_kb # 6. Now entries became unexpected 1 because actually no entries!!! # cat per_cpu/cpu0/stats entries: 1 [...] read events: 0 To fix it, introduce 'page_removed' field to count total removed pages since last reset, then use it to let read iterators reset themselves instead of changing the 'read' pointer. Link: https://lore.kernel.org/linux-trace-kernel/20230724054040.3489499-1-z= hengyejian1@huawei.com Cc: Cc: Fixes: 83f40318dab0 ("ring-buffer: Make removal of ring buffer pages atomic= ") Signed-off-by: Zheng Yejian Signed-off-by: Steven Rostedt (Google) --- kernel/trace/ring_buffer.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index de061dd47313..46b4a3c7c3bf 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -523,6 +523,8 @@ struct ring_buffer_per_cpu { rb_time_t before_stamp; u64 event_stamp[MAX_NEST]; u64 read_stamp; + /* pages removed since last reset */ + unsigned long pages_removed; /* ring buffer pages to update, > 0 to add, < 0 to remove */ long nr_pages_to_update; struct list_head new_pages; /* new pages to add */ @@ -559,6 +561,7 @@ struct ring_buffer_iter { struct buffer_page *head_page; struct buffer_page *cache_reader_page; unsigned long cache_read; + unsigned long cache_pages_removed; u64 read_stamp; u64 page_stamp; struct ring_buffer_event *event; @@ -1957,6 +1960,8 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffe= r, unsigned long nr_pages) to_remove =3D rb_list_head(to_remove)->next; head_bit |=3D (unsigned long)to_remove & RB_PAGE_HEAD; } + /* Read iterators need to reset themselves when some pages removed */ + cpu_buffer->pages_removed +=3D nr_removed; =20 next_page =3D rb_list_head(to_remove)->next; =20 @@ -1978,12 +1983,6 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buff= er, unsigned long nr_pages) cpu_buffer->head_page =3D list_entry(next_page, struct buffer_page, list); =20 - /* - * change read pointer to make sure any read iterators reset - * themselves - */ - cpu_buffer->read =3D 0; - /* pages are removed, resume tracing and then free the pages */ atomic_dec(&cpu_buffer->record_disabled); raw_spin_unlock_irq(&cpu_buffer->reader_lock); @@ -4395,6 +4394,7 @@ static void rb_iter_reset(struct ring_buffer_iter *it= er) =20 iter->cache_reader_page =3D iter->head_page; iter->cache_read =3D cpu_buffer->read; + iter->cache_pages_removed =3D cpu_buffer->pages_removed; =20 if (iter->head) { iter->read_stamp =3D cpu_buffer->read_stamp; @@ -4849,12 +4849,13 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) buffer =3D cpu_buffer->buffer; =20 /* - * Check if someone performed a consuming read to - * the buffer. A consuming read invalidates the iterator - * and we need to reset the iterator in this case. + * Check if someone performed a consuming read to the buffer + * or removed some pages from the buffer. In these cases, + * iterator was invalidated and we need to reset it. */ if (unlikely(iter->cache_read !=3D cpu_buffer->read || - iter->cache_reader_page !=3D cpu_buffer->reader_page)) + iter->cache_reader_page !=3D cpu_buffer->reader_page || + iter->cache_pages_removed !=3D cpu_buffer->pages_removed)) rb_iter_reset(iter); =20 again: @@ -5298,6 +5299,7 @@ rb_reset_cpu(struct ring_buffer_per_cpu *cpu_buffer) cpu_buffer->last_overrun =3D 0; =20 rb_head_page_activate(cpu_buffer); + cpu_buffer->pages_removed =3D 0; } =20 /* Must have disabled the cpu buffer then done a synchronize_rcu */ --=20 2.40.1 From nobody Sun Feb 8 01:30:36 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 75243C001E0 for ; Sat, 29 Jul 2023 18:34:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229846AbjG2Se3 (ORCPT ); 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charset="utf-8" From: Gaosheng Cui Fix kernel-doc warnings: kernel/trace/ring_buffer.c:954: warning: Function parameter or member 'cpu' not described in 'ring_buffer_wake_waiters' kernel/trace/ring_buffer.c:3383: warning: Excess function parameter 'event' description in 'ring_buffer_unlock_commit' kernel/trace/ring_buffer.c:5359: warning: Excess function parameter 'cpu' description in 'ring_buffer_reset_online_cpus' Link: https://lkml.kernel.org/r/20230724140827.1023266-2-cuigaosheng1@huawe= i.com Cc: Signed-off-by: Gaosheng Cui Signed-off-by: Steven Rostedt (Google) --- kernel/trace/ring_buffer.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 46b4a3c7c3bf..52dea5dd5362 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -950,6 +950,7 @@ static void rb_wake_up_waiters(struct irq_work *work) /** * ring_buffer_wake_waiters - wake up any waiters on this ring buffer * @buffer: The ring buffer to wake waiters on + * @cpu: The CPU buffer to wake waiters on * * In the case of a file that represents a ring buffer is closing, * it is prudent to wake up any waiters that are on this. @@ -3375,7 +3376,6 @@ void ring_buffer_nest_end(struct trace_buffer *buffer) /** * ring_buffer_unlock_commit - commit a reserved * @buffer: The buffer to commit to - * @event: The event pointer to commit. * * This commits the data to the ring buffer, and releases any locks held. * @@ -5358,7 +5358,6 @@ EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); /** * ring_buffer_reset_online_cpus - reset a ring buffer per CPU buffer * @buffer: The ring buffer to reset a per cpu buffer of - * @cpu: The CPU buffer to be reset */ void ring_buffer_reset_online_cpus(struct trace_buffer *buffer) { --=20 2.40.1 From nobody Sun Feb 8 01:30:36 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 41D66C41513 for ; Sat, 29 Jul 2023 18:34:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229852AbjG2Seb (ORCPT ); Sat, 29 Jul 2023 14:34:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43112 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229729AbjG2SeZ (ORCPT ); Sat, 29 Jul 2023 14:34:25 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A83CC3582 for ; 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charset="utf-8" From: Gaosheng Cui Fix kernel-doc warning: kernel/trace/trace_events_synth.c:1257: warning: Function parameter or member 'mod' not described in 'synth_event_gen_cmd_array_start' Link: https://lkml.kernel.org/r/20230724140827.1023266-3-cuigaosheng1@huawe= i.com Cc: Signed-off-by: Gaosheng Cui Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events_synth.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_= synth.c index d6a70aff2410..dd398afc8e25 100644 --- a/kernel/trace/trace_events_synth.c +++ b/kernel/trace/trace_events_synth.c @@ -1230,6 +1230,7 @@ EXPORT_SYMBOL_GPL(__synth_event_gen_cmd_start); * synth_event_gen_cmd_array_start - Start synthetic event command from an= array * @cmd: A pointer to the dynevent_cmd struct representing the new event * @name: The name of the synthetic event + * @mod: The module creating the event, NULL if not created from a module * @fields: An array of type/name field descriptions * @n_fields: The number of field descriptions contained in the fields arr= ay * --=20 2.40.1 From nobody Sun Feb 8 01:30:36 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 538DBC001DC for ; Sat, 29 Jul 2023 18:34:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229868AbjG2See (ORCPT ); Sat, 29 Jul 2023 14:34:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43114 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229764AbjG2SeZ (ORCPT ); Sat, 29 Jul 2023 14:34:25 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EA4703585 for ; Sat, 29 Jul 2023 11:34:23 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 74BBD60A0A for ; Sat, 29 Jul 2023 18:34:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E2959C433C7; Sat, 29 Jul 2023 18:34:22 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.96) (envelope-from ) id 1qPolh-0035K7-2l; Sat, 29 Jul 2023 14:34:21 -0400 Message-ID: <20230729183421.670475369@goodmis.org> User-Agent: quilt/0.66 Date: Sat, 29 Jul 2023 14:33:37 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Andrew Morton , Gaosheng Cui Subject: [for-linus][PATCH 4/7] tracing: Fix kernel-doc warnings in trace_events_trigger.c References: <20230729183333.357029101@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Gaosheng Cui Fix kernel-doc warnings: kernel/trace/trace_events_trigger.c:59: warning: Function parameter or member 'buffer' not described in 'event_triggers_call' kernel/trace/trace_events_trigger.c:59: warning: Function parameter or member 'event' not described in 'event_triggers_call' Link: https://lkml.kernel.org/r/20230724140827.1023266-4-cuigaosheng1@huawe= i.com Cc: Signed-off-by: Gaosheng Cui Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events_trigger.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_event= s_trigger.c index e535959939d3..46439e3bcec4 100644 --- a/kernel/trace/trace_events_trigger.c +++ b/kernel/trace/trace_events_trigger.c @@ -31,7 +31,9 @@ void trigger_data_free(struct event_trigger_data *data) /** * event_triggers_call - Call triggers associated with a trace event * @file: The trace_event_file associated with the event + * @buffer: The ring buffer that the event is being written to * @rec: The trace entry for the event, NULL for unconditional invocation + * @event: The event meta data in the ring buffer * * For each trigger associated with an event, invoke the trigger * function registered with the associated trigger command. If rec is --=20 2.40.1 From nobody Sun Feb 8 01:30:36 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3232CC001DF for ; Sat, 29 Jul 2023 18:34:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229817AbjG2Sek (ORCPT ); Sat, 29 Jul 2023 14:34:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43120 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229818AbjG2SeZ (ORCPT ); Sat, 29 Jul 2023 14:34:25 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E257B3588 for ; Sat, 29 Jul 2023 11:34:24 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 9921560AD7 for ; Sat, 29 Jul 2023 18:34:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 06B4DC433C8; Sat, 29 Jul 2023 18:34:23 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.96) (envelope-from ) id 1qPoli-0035Kg-0D; Sat, 29 Jul 2023 14:34:22 -0400 Message-ID: <20230729183421.877315009@goodmis.org> User-Agent: quilt/0.66 Date: Sat, 29 Jul 2023 14:33:38 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Andrew Morton , Gaosheng Cui Subject: [for-linus][PATCH 5/7] tracing: Fix kernel-doc warnings in trace_seq.c References: <20230729183333.357029101@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Gaosheng Cui Fix kernel-doc warning: kernel/trace/trace_seq.c:142: warning: Function parameter or member 'args' not described in 'trace_seq_vprintf' Link: https://lkml.kernel.org/r/20230724140827.1023266-5-cuigaosheng1@huawe= i.com Cc: Signed-off-by: Gaosheng Cui Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_seq.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c index e5e299260d0c..bac06ee3b98b 100644 --- a/kernel/trace/trace_seq.c +++ b/kernel/trace/trace_seq.c @@ -131,6 +131,7 @@ EXPORT_SYMBOL_GPL(trace_seq_bitmask); * trace_seq_vprintf - sequence printing of trace information * @s: trace sequence descriptor * @fmt: printf format string + * @args: Arguments for the format string * * The tracer may use either sequence operations or its own * copy to user routines. To simplify formatting of a trace --=20 2.40.1 From nobody Sun Feb 8 01:30:36 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8AA88C04FDF for ; Sat, 29 Jul 2023 18:34:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229873AbjG2Seg (ORCPT ); Sat, 29 Jul 2023 14:34:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43116 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229798AbjG2SeZ (ORCPT ); Sat, 29 Jul 2023 14:34:25 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C49ED30FA for ; Sat, 29 Jul 2023 11:34:24 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id B8D7E60AF3 for ; Sat, 29 Jul 2023 18:34:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 31AD5C433CB; Sat, 29 Jul 2023 18:34:23 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.96) (envelope-from ) id 1qPoli-0035LE-0s; Sat, 29 Jul 2023 14:34:22 -0400 Message-ID: <20230729183422.087580772@goodmis.org> User-Agent: quilt/0.66 Date: Sat, 29 Jul 2023 14:33:39 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Andrew Morton , YueHaibing Subject: [for-linus][PATCH 6/7] ftrace: Remove unused extern declarations References: <20230729183333.357029101@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: YueHaibing commit 6a9c981b1e96 ("ftrace: Remove unused function ftrace_arch_read_dyn_i= nfo()") left ftrace_arch_read_dyn_info() extern declaration. And commit 1d74f2a0f64b ("ftrace: remove ftrace_ip_converted()") leave ftrace_ip_converted() declaration. Link: https://lore.kernel.org/linux-trace-kernel/20230725134808.9716-1-yueh= aibing@huawei.com Cc: Cc: Signed-off-by: YueHaibing Signed-off-by: Steven Rostedt (Google) --- include/linux/ftrace.h | 4 ---- 1 file changed, 4 deletions(-) diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index ce156c7704ee..aad9cf8876b5 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -684,7 +684,6 @@ void __init ftrace_set_early_filter(struct ftrace_ops *ops, char *buf, int enable); =20 /* defined in arch */ -extern int ftrace_ip_converted(unsigned long ip); extern int ftrace_dyn_arch_init(void); extern void ftrace_replace_code(int enable); extern int ftrace_update_ftrace_func(ftrace_func_t func); @@ -859,9 +858,6 @@ static inline int ftrace_modify_call(struct dyn_ftrace = *rec, unsigned long old_a } #endif =20 -/* May be defined in arch */ -extern int ftrace_arch_read_dyn_info(char *buf, int size); - extern int skip_trace(unsigned long ip); extern void ftrace_module_init(struct module *mod); extern void ftrace_module_enable(struct module *mod); --=20 2.40.1 From nobody Sun Feb 8 01:30:36 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BD8BEC001DC for ; Sat, 29 Jul 2023 18:34:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229883AbjG2Sem (ORCPT ); Sat, 29 Jul 2023 14:34:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43118 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229819AbjG2SeZ (ORCPT ); Sat, 29 Jul 2023 14:34:25 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CC9DA30FC for ; Sat, 29 Jul 2023 11:34:24 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id DDADF60909 for ; Sat, 29 Jul 2023 18:34:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 58B3FC433D9; Sat, 29 Jul 2023 18:34:23 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.96) (envelope-from ) id 1qPoli-0035Lo-1X; Sat, 29 Jul 2023 14:34:22 -0400 Message-ID: <20230729183422.299073875@goodmis.org> User-Agent: quilt/0.66 Date: Sat, 29 Jul 2023 14:33:40 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Andrew Morton , Zheng Yejian Subject: [for-linus][PATCH 7/7] tracing: Fix warning in trace_buffered_event_disable() References: <20230729183333.357029101@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Zheng Yejian Warning happened in trace_buffered_event_disable() at WARN_ON_ONCE(!trace_buffered_event_ref) Call Trace: ? __warn+0xa5/0x1b0 ? trace_buffered_event_disable+0x189/0x1b0 __ftrace_event_enable_disable+0x19e/0x3e0 free_probe_data+0x3b/0xa0 unregister_ftrace_function_probe_func+0x6b8/0x800 event_enable_func+0x2f0/0x3d0 ftrace_process_regex.isra.0+0x12d/0x1b0 ftrace_filter_write+0xe6/0x140 vfs_write+0x1c9/0x6f0 [...] The cause of the warning is in __ftrace_event_enable_disable(), trace_buffered_event_enable() was called once while trace_buffered_event_disable() was called twice. Reproduction script show as below, for analysis, see the comments: ``` #!/bin/bash cd /sys/kernel/tracing/ # 1. Register a 'disable_event' command, then: # 1) SOFT_DISABLED_BIT was set; # 2) trace_buffered_event_enable() was called first time; echo 'cmdline_proc_show:disable_event:initcall:initcall_finish' > \ set_ftrace_filter # 2. Enable the event registered, then: # 1) SOFT_DISABLED_BIT was cleared; # 2) trace_buffered_event_disable() was called first time; echo 1 > events/initcall/initcall_finish/enable # 3. Try to call into cmdline_proc_show(), then SOFT_DISABLED_BIT was # set again!!! cat /proc/cmdline # 4. Unregister the 'disable_event' command, then: # 1) SOFT_DISABLED_BIT was cleared again; # 2) trace_buffered_event_disable() was called second time!!! echo '!cmdline_proc_show:disable_event:initcall:initcall_finish' > \ set_ftrace_filter ``` To fix it, IIUC, we can change to call trace_buffered_event_enable() at fist time soft-mode enabled, and call trace_buffered_event_disable() at last time soft-mode disabled. Link: https://lore.kernel.org/linux-trace-kernel/20230726095804.920457-1-zh= engyejian1@huawei.com Cc: Fixes: 0fc1b09ff1ff ("tracing: Use temp buffer when filtering events") Signed-off-by: Zheng Yejian Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events.c | 14 ++++---------- 1 file changed, 4 insertions(+), 10 deletions(-) diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 5d6ae4eae510..578f1f7d49a6 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -611,7 +611,6 @@ static int __ftrace_event_enable_disable(struct trace_e= vent_file *file, { struct trace_event_call *call =3D file->event_call; struct trace_array *tr =3D file->tr; - unsigned long file_flags =3D file->flags; int ret =3D 0; int disable; =20 @@ -635,6 +634,8 @@ static int __ftrace_event_enable_disable(struct trace_e= vent_file *file, break; disable =3D file->flags & EVENT_FILE_FL_SOFT_DISABLED; clear_bit(EVENT_FILE_FL_SOFT_MODE_BIT, &file->flags); + /* Disable use of trace_buffered_event */ + trace_buffered_event_disable(); } else disable =3D !(file->flags & EVENT_FILE_FL_SOFT_MODE); =20 @@ -673,6 +674,8 @@ static int __ftrace_event_enable_disable(struct trace_e= vent_file *file, if (atomic_inc_return(&file->sm_ref) > 1) break; set_bit(EVENT_FILE_FL_SOFT_MODE_BIT, &file->flags); + /* Enable use of trace_buffered_event */ + trace_buffered_event_enable(); } =20 if (!(file->flags & EVENT_FILE_FL_ENABLED)) { @@ -712,15 +715,6 @@ static int __ftrace_event_enable_disable(struct trace_= event_file *file, break; } =20 - /* Enable or disable use of trace_buffered_event */ - if ((file_flags & EVENT_FILE_FL_SOFT_DISABLED) !=3D - (file->flags & EVENT_FILE_FL_SOFT_DISABLED)) { - if (file->flags & EVENT_FILE_FL_SOFT_DISABLED) - trace_buffered_event_enable(); - else - trace_buffered_event_disable(); - } - return ret; } =20 --=20 2.40.1