From mboxrd@z Thu Jan 1 00:00:00 1970 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 1660EC3527D for ; Tue, 5 Apr 2022 13:24:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1387797AbiDENTG (ORCPT ); Tue, 5 Apr 2022 09:19:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43410 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344288AbiDEJTE (ORCPT ); Tue, 5 Apr 2022 05:19:04 -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 200BA23BDA; Tue, 5 Apr 2022 02:07:25 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id A3B7661571; Tue, 5 Apr 2022 09:07:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AB940C385A0; Tue, 5 Apr 2022 09:07:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649149644; bh=bSb3HqwUqzg12TWINhvRaliTGErk6UBUU6LHoXhpwQI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zFYWSKtL6hY8UpP6Erk1x3m7sB8hl2bzTzXuy8SVKI6oDX81UyO6iBi4gZ8ro+05/ s8bu7Lce6RD82TF8dma1bbJrO7Dnn6cQSehr7s/kkWn1vVOByTiAB+Yjf1jLSQKj9T vxZw7C50IJDH23jhByKJOcqD/lpAw/Pp7WH7816E= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Abhijeet Dharmapurikar , Valentin Schneider , "Peter Zijlstra (Intel)" , "Steven Rostedt (Google)" , Sasha Levin Subject: [PATCH 5.16 0788/1017] sched/tracing: Dont re-read p->state when emitting sched_switch event Date: Tue, 5 Apr 2022 09:28:21 +0200 Message-Id: <20220405070417.645056019@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070354.155796697@linuxfoundation.org> References: <20220405070354.155796697@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Valentin Schneider [ Upstream commit fa2c3254d7cfff5f7a916ab928a562d1165f17bb ] As of commit c6e7bd7afaeb ("sched/core: Optimize ttwu() spinning on p->on_cpu") the following sequence becomes possible: p->__state = TASK_INTERRUPTIBLE; __schedule() deactivate_task(p); ttwu() READ !p->on_rq p->__state=TASK_WAKING trace_sched_switch() __trace_sched_switch_state() task_state_index() return 0; TASK_WAKING isn't in TASK_REPORT, so the task appears as TASK_RUNNING in the trace event. Prevent this by pushing the value read from __schedule() down the trace event. Reported-by: Abhijeet Dharmapurikar Signed-off-by: Valentin Schneider Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Steven Rostedt (Google) Link: https://lore.kernel.org/r/20220120162520.570782-2-valentin.schneider@arm.com Signed-off-by: Sasha Levin --- include/linux/sched.h | 11 ++++++++--- include/trace/events/sched.h | 11 +++++++---- kernel/sched/core.c | 4 ++-- kernel/trace/fgraph.c | 4 +++- kernel/trace/ftrace.c | 4 +++- kernel/trace/trace_events.c | 8 ++++++-- kernel/trace/trace_osnoise.c | 4 +++- kernel/trace/trace_sched_switch.c | 1 + kernel/trace/trace_sched_wakeup.c | 1 + 9 files changed, 34 insertions(+), 14 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index ee5ed8821963..084de9b70a77 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1612,10 +1612,10 @@ static inline pid_t task_pgrp_nr(struct task_struct *tsk) #define TASK_REPORT_IDLE (TASK_REPORT + 1) #define TASK_REPORT_MAX (TASK_REPORT_IDLE << 1) -static inline unsigned int task_state_index(struct task_struct *tsk) +static inline unsigned int __task_state_index(unsigned int tsk_state, + unsigned int tsk_exit_state) { - unsigned int tsk_state = READ_ONCE(tsk->__state); - unsigned int state = (tsk_state | tsk->exit_state) & TASK_REPORT; + unsigned int state = (tsk_state | tsk_exit_state) & TASK_REPORT; BUILD_BUG_ON_NOT_POWER_OF_2(TASK_REPORT_MAX); @@ -1625,6 +1625,11 @@ static inline unsigned int task_state_index(struct task_struct *tsk) return fls(state); } +static inline unsigned int task_state_index(struct task_struct *tsk) +{ + return __task_state_index(READ_ONCE(tsk->__state), tsk->exit_state); +} + static inline char task_index_to_char(unsigned int state) { static const char state_char[] = "RSDTtXZPI"; diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h index 94640482cfe7..65e786756321 100644 --- a/include/trace/events/sched.h +++ b/include/trace/events/sched.h @@ -187,7 +187,9 @@ DEFINE_EVENT(sched_wakeup_template, sched_wakeup_new, TP_ARGS(p)); #ifdef CREATE_TRACE_POINTS -static inline long __trace_sched_switch_state(bool preempt, struct task_struct *p) +static inline long __trace_sched_switch_state(bool preempt, + unsigned int prev_state, + struct task_struct *p) { unsigned int state; @@ -208,7 +210,7 @@ static inline long __trace_sched_switch_state(bool preempt, struct task_struct * * it for left shift operation to get the correct task->state * mapping. */ - state = task_state_index(p); + state = __task_state_index(prev_state, p->exit_state); return state ? (1 << (state - 1)) : state; } @@ -220,10 +222,11 @@ static inline long __trace_sched_switch_state(bool preempt, struct task_struct * TRACE_EVENT(sched_switch, TP_PROTO(bool preempt, + unsigned int prev_state, struct task_struct *prev, struct task_struct *next), - TP_ARGS(preempt, prev, next), + TP_ARGS(preempt, prev_state, prev, next), TP_STRUCT__entry( __array( char, prev_comm, TASK_COMM_LEN ) @@ -239,7 +242,7 @@ TRACE_EVENT(sched_switch, memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN); __entry->prev_pid = prev->pid; __entry->prev_prio = prev->prio; - __entry->prev_state = __trace_sched_switch_state(preempt, prev); + __entry->prev_state = __trace_sched_switch_state(preempt, prev_state, prev); memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN); __entry->next_pid = next->pid; __entry->next_prio = next->prio; diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 0e4b8214af31..527ee363db3f 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4821,7 +4821,7 @@ static struct rq *finish_task_switch(struct task_struct *prev) { struct rq *rq = this_rq(); struct mm_struct *mm = rq->prev_mm; - long prev_state; + unsigned int prev_state; /* * The previous task will have left us with a preempt_count of 2 @@ -6257,7 +6257,7 @@ static void __sched notrace __schedule(unsigned int sched_mode) migrate_disable_switch(rq, prev); psi_sched_switch(prev, next, !task_on_rq_queued(prev)); - trace_sched_switch(sched_mode & SM_MASK_PREEMPT, prev, next); + trace_sched_switch(sched_mode & SM_MASK_PREEMPT, prev_state, prev, next); /* Also unlocks the rq: */ rq = context_switch(rq, prev, next, &rf); diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c index 22061d38fc00..19028e072cdb 100644 --- a/kernel/trace/fgraph.c +++ b/kernel/trace/fgraph.c @@ -415,7 +415,9 @@ static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list) static void ftrace_graph_probe_sched_switch(void *ignore, bool preempt, - struct task_struct *prev, struct task_struct *next) + unsigned int prev_state, + struct task_struct *prev, + struct task_struct *next) { unsigned long long timestamp; int index; diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index be5f6b32a012..bbfa4606cba6 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -7317,7 +7317,9 @@ ftrace_func_t ftrace_ops_get_func(struct ftrace_ops *ops) static void ftrace_filter_pid_sched_switch_probe(void *data, bool preempt, - struct task_struct *prev, struct task_struct *next) + unsigned int prev_state, + struct task_struct *prev, + struct task_struct *next) { struct trace_array *tr = data; struct trace_pid_list *pid_list; diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 92be9cb1d7d4..c097d89ca946 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -759,7 +759,9 @@ void trace_event_follow_fork(struct trace_array *tr, bool enable) static void event_filter_pid_sched_switch_probe_pre(void *data, bool preempt, - struct task_struct *prev, struct task_struct *next) + unsigned int prev_state, + struct task_struct *prev, + struct task_struct *next) { struct trace_array *tr = data; struct trace_pid_list *no_pid_list; @@ -783,7 +785,9 @@ event_filter_pid_sched_switch_probe_pre(void *data, bool preempt, static void event_filter_pid_sched_switch_probe_post(void *data, bool preempt, - struct task_struct *prev, struct task_struct *next) + unsigned int prev_state, + struct task_struct *prev, + struct task_struct *next) { struct trace_array *tr = data; struct trace_pid_list *no_pid_list; diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c index b6da7bd2383d..b3b8060e8bdd 100644 --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -1168,7 +1168,9 @@ thread_exit(struct osnoise_variables *osn_var, struct task_struct *t) * used to record the beginning and to report the end of a thread noise window. */ static void -trace_sched_switch_callback(void *data, bool preempt, struct task_struct *p, +trace_sched_switch_callback(void *data, bool preempt, + unsigned int prev_state, + struct task_struct *p, struct task_struct *n) { struct osnoise_variables *osn_var = this_cpu_osn_var(); diff --git a/kernel/trace/trace_sched_switch.c b/kernel/trace/trace_sched_switch.c index e304196d7c28..993b0ed10d8c 100644 --- a/kernel/trace/trace_sched_switch.c +++ b/kernel/trace/trace_sched_switch.c @@ -22,6 +22,7 @@ static DEFINE_MUTEX(sched_register_mutex); static void probe_sched_switch(void *ignore, bool preempt, + unsigned int prev_state, struct task_struct *prev, struct task_struct *next) { int flags; diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c index 2402de520eca..46429f9a96fa 100644 --- a/kernel/trace/trace_sched_wakeup.c +++ b/kernel/trace/trace_sched_wakeup.c @@ -426,6 +426,7 @@ tracing_sched_wakeup_trace(struct trace_array *tr, static void notrace probe_wakeup_sched_switch(void *ignore, bool preempt, + unsigned int prev_state, struct task_struct *prev, struct task_struct *next) { struct trace_array_cpu *data; -- 2.34.1