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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0DA65C433EF for ; Sat, 9 Oct 2021 10:09:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E968060EE3 for ; Sat, 9 Oct 2021 10:09:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244995AbhJIKKz (ORCPT ); Sat, 9 Oct 2021 06:10:55 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:49668 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244857AbhJIKKD (ORCPT ); Sat, 9 Oct 2021 06:10:03 -0400 Date: Sat, 09 Oct 2021 10:07:40 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1633774061; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=60/+SY8E0h2m9+++lh0PA/3g3TptwzZEqR6jwApUM3M=; b=nAtQ2DoW+6hhPSDkzurd1Sit4P/vrwZs6ywVsFNUzItO8JE/dXN/LUF5DSmp4ePCL98K2I pLREDUDHQvFYuq15wbKE5DqnBuLM25QR2QnS0JDEZ8KZHWC3HQyVyeNOoa3ewAVxrTqPU8 crC0xGtkvLsI2Kx0pbEkMlIwj0R5uQrlLngWU5xUlvs0qyp5p3al2jIsPVApCG/3jy0pyx qX0IdB7+nkuhvSte0VkVBiPHLW5SVQuNT+t3NAn6Yt+H2JCZ/AJtshqtr3AGx7K2/E/owu XQK/iuN8WJEDjOxi1Pl49oFgAzvNSWhl60gqN3VdqX65Yi6Qb71F2LUYfE2k4w== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1633774061; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=60/+SY8E0h2m9+++lh0PA/3g3TptwzZEqR6jwApUM3M=; b=gIVZYXNVhv2zpuD/Je1SRRB5O9Juc2Mjl+48oHHmU9GOj/AdeN9zjtvPU0k2jIjyAMYvct mShjiSghrvXYLuDg== From: "tip-bot2 for Peter Zijlstra" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/core] sched,rcu: Rework try_invoke_on_locked_down_task() Cc: "Peter Zijlstra (Intel)" , "Paul E. McKenney" , Vasily Gorbik , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20210929152428.649944917@infradead.org> References: <20210929152428.649944917@infradead.org> MIME-Version: 1.0 Message-ID: <163377406051.25758.17414280353986792435.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the sched/core branch of tip: Commit-ID: 9b3c4ab3045e953670c7de9c1165fae5358a7237 Gitweb: https://git.kernel.org/tip/9b3c4ab3045e953670c7de9c1165fae5358a7237 Author: Peter Zijlstra AuthorDate: Tue, 21 Sep 2021 21:54:32 +02:00 Committer: Peter Zijlstra CommitterDate: Thu, 07 Oct 2021 13:51:15 +02:00 sched,rcu: Rework try_invoke_on_locked_down_task() Give try_invoke_on_locked_down_task() a saner name and have it return an int so that the caller might distinguish between different reasons of failure. Signed-off-by: Peter Zijlstra (Intel) Acked-by: Paul E. McKenney Acked-by: Vasily Gorbik Tested-by: Vasily Gorbik # on s390 Link: https://lkml.kernel.org/r/20210929152428.649944917@infradead.org --- include/linux/wait.h | 3 ++- kernel/rcu/tasks.h | 12 ++++++------ kernel/rcu/tree_stall.h | 8 ++++---- kernel/sched/core.c | 6 +++--- 4 files changed, 15 insertions(+), 14 deletions(-) diff --git a/include/linux/wait.h b/include/linux/wait.h index 93dab0e..2d0df57 100644 --- a/include/linux/wait.h +++ b/include/linux/wait.h @@ -1160,6 +1160,7 @@ int autoremove_wake_function(struct wait_queue_entry *wq_entry, unsigned mode, i (wait)->flags = 0; \ } while (0) -bool try_invoke_on_locked_down_task(struct task_struct *p, bool (*func)(struct task_struct *t, void *arg), void *arg); +typedef int (*task_call_f)(struct task_struct *p, void *arg); +extern int task_call_func(struct task_struct *p, task_call_f func, void *arg); #endif /* _LINUX_WAIT_H */ diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index 806160c..171bc84 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -928,7 +928,7 @@ reset_ipi: } /* Callback function for scheduler to check locked-down task. */ -static bool trc_inspect_reader(struct task_struct *t, void *arg) +static int trc_inspect_reader(struct task_struct *t, void *arg) { int cpu = task_cpu(t); bool in_qs = false; @@ -939,7 +939,7 @@ static bool trc_inspect_reader(struct task_struct *t, void *arg) // If no chance of heavyweight readers, do it the hard way. if (!ofl && !IS_ENABLED(CONFIG_TASKS_TRACE_RCU_READ_MB)) - return false; + return -EINVAL; // If heavyweight readers are enabled on the remote task, // we can inspect its state despite its currently running. @@ -947,7 +947,7 @@ static bool trc_inspect_reader(struct task_struct *t, void *arg) n_heavy_reader_attempts++; if (!ofl && // Check for "running" idle tasks on offline CPUs. !rcu_dynticks_zero_in_eqs(cpu, &t->trc_reader_nesting)) - return false; // No quiescent state, do it the hard way. + return -EINVAL; // No quiescent state, do it the hard way. n_heavy_reader_updates++; if (ofl) n_heavy_reader_ofl_updates++; @@ -962,7 +962,7 @@ static bool trc_inspect_reader(struct task_struct *t, void *arg) t->trc_reader_checked = true; if (in_qs) - return true; // Already in quiescent state, done!!! + return 0; // Already in quiescent state, done!!! // The task is in a read-side critical section, so set up its // state so that it will awaken the grace-period kthread upon exit @@ -970,7 +970,7 @@ static bool trc_inspect_reader(struct task_struct *t, void *arg) atomic_inc(&trc_n_readers_need_end); // One more to wait on. WARN_ON_ONCE(READ_ONCE(t->trc_reader_special.b.need_qs)); WRITE_ONCE(t->trc_reader_special.b.need_qs, true); - return true; + return 0; } /* Attempt to extract the state for the specified task. */ @@ -992,7 +992,7 @@ static void trc_wait_for_one_reader(struct task_struct *t, // Attempt to nail down the task for inspection. get_task_struct(t); - if (try_invoke_on_locked_down_task(t, trc_inspect_reader, NULL)) { + if (!task_call_func(t, trc_inspect_reader, NULL)) { put_task_struct(t); return; } diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index 677ee3d..5e2fa6f 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -240,16 +240,16 @@ struct rcu_stall_chk_rdr { * Report out the state of a not-running task that is stalling the * current RCU grace period. */ -static bool check_slow_task(struct task_struct *t, void *arg) +static int check_slow_task(struct task_struct *t, void *arg) { struct rcu_stall_chk_rdr *rscrp = arg; if (task_curr(t)) - return false; // It is running, so decline to inspect it. + return -EBUSY; // It is running, so decline to inspect it. rscrp->nesting = t->rcu_read_lock_nesting; rscrp->rs = t->rcu_read_unlock_special; rscrp->on_blkd_list = !list_empty(&t->rcu_node_entry); - return true; + return 0; } /* @@ -283,7 +283,7 @@ static int rcu_print_task_stall(struct rcu_node *rnp, unsigned long flags) raw_spin_unlock_irqrestore_rcu_node(rnp, flags); while (i) { t = ts[--i]; - if (!try_invoke_on_locked_down_task(t, check_slow_task, &rscr)) + if (task_call_func(t, check_slow_task, &rscr)) pr_cont(" P%d", t->pid); else pr_cont(" P%d/%d:%c%c%c%c", diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 8a9aeac..74db3c3 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4110,7 +4110,7 @@ out: } /** - * try_invoke_on_locked_down_task - Invoke a function on task in fixed state + * task_call_func - Invoke a function on task in fixed state * @p: Process for which the function is to be invoked, can be @current. * @func: Function to invoke. * @arg: Argument to function. @@ -4123,12 +4123,12 @@ out: * Returns: * Whatever @func returns */ -bool try_invoke_on_locked_down_task(struct task_struct *p, bool (*func)(struct task_struct *t, void *arg), void *arg) +int task_call_func(struct task_struct *p, task_call_f func, void *arg) { struct rq *rq = NULL; unsigned int state; struct rq_flags rf; - bool ret = false; + int ret; raw_spin_lock_irqsave(&p->pi_lock, rf.flags);