From patchwork Mon Jun 12 09:07:29 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Zijlstra X-Patchwork-Id: 13276156 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 464BAC7EE25 for ; Mon, 12 Jun 2023 09:57:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234987AbjFLJ5T (ORCPT ); Mon, 12 Jun 2023 05:57:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33802 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232392AbjFLJyV (ORCPT ); Mon, 12 Jun 2023 05:54:21 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E2D994C09; Mon, 12 Jun 2023 02:38:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-ID:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=vDHS8Plr2cencdpiH/auo6E776oNoOhgYdcpKlgKc4Q=; b=XfspiS8Usbqb2dpT01GShTpXYF 0wwyX4AcSTYBMwe4XCE0JXv0GEXukM5Z+wJrQ5ydemtoQKvufj+e0HtUrkEv50Xk/7NS5f+kXoBH9 NRHSIXz+gP5a9fY839hRRMg3XMU8GiI1b3Pt7sMPV4OqaS+t6EGwmATXLiqnN97MCbKsORuHO2Pr8 vz3ITtR3OFV8f2JSdzAkJYccKWoz7g4QT5P8RYF55XvZaHjj/8iBTBPAQu9E+hOhqdBtj1hgmbPlJ c78PyIoTct3THwyJGFh1bmBuUYmoopUkjAyRnngrF2sMB5pJoA+wZWUNb+w3pp3J3RKYPSrqc3iKz xqluhn6g==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1q8e0g-008kPA-1f; Mon, 12 Jun 2023 09:38:51 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 04CC13031B9; Mon, 12 Jun 2023 11:38:49 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id 53B9E30A77B56; Mon, 12 Jun 2023 11:38:48 +0200 (CEST) Message-ID: <20230612093538.640502622@infradead.org> User-Agent: quilt/0.66 Date: Mon, 12 Jun 2023 11:07:29 +0200 From: Peter Zijlstra To: torvalds@linux-foundation.org, keescook@chromium.org, gregkh@linuxfoundation.org, pbonzini@redhat.com Cc: masahiroy@kernel.org, nathan@kernel.org, ndesaulniers@google.com, nicolas@fjasle.eu, catalin.marinas@arm.com, will@kernel.org, vkoul@kernel.org, trix@redhat.com, ojeda@kernel.org, peterz@infradead.org, mingo@redhat.com, longman@redhat.com, boqun.feng@gmail.com, dennis@kernel.org, tj@kernel.org, cl@linux.com, acme@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, namhyung@kernel.org, irogers@google.com, adrian.hunter@intel.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, paulmck@kernel.org, frederic@kernel.org, quic_neeraju@quicinc.com, joel@joelfernandes.org, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, rientjes@google.com, vbabka@suse.cz, roman.gushchin@linux.dev, 42.hyeyoo@gmail.com, apw@canonical.com, joe@perches.com, dwaipayanray1@gmail.com, lukas.bulwahn@gmail.com, john.johansen@canonical.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, dmaengine@vger.kernel.org, llvm@lists.linux.dev, linux-perf-users@vger.kernel.org, rcu@vger.kernel.org, linux-security-module@vger.kernel.org, tglx@linutronix.de, ravi.bangoria@amd.com, error27@gmail.com, luc.vanoostenryck@gmail.com Subject: [PATCH v3 16/57] sched: Simplify sched_{set,get}affinity() References: <20230612090713.652690195@infradead.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org Use guards to reduce gotos and simplify control flow. Signed-off-by: Peter Zijlstra (Intel) --- kernel/sched/core.c | 53 +++++++++++++--------------------------------------- 1 file changed, 14 insertions(+), 39 deletions(-) --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8258,39 +8258,24 @@ long sched_setaffinity(pid_t pid, const { struct affinity_context ac; struct cpumask *user_mask; - struct task_struct *p; int retval; - rcu_read_lock(); - - p = find_process_by_pid(pid); - if (!p) { - rcu_read_unlock(); + CLASS(find_get_task, p)(pid); + if (!p) return -ESRCH; - } - /* Prevent p going away */ - get_task_struct(p); - rcu_read_unlock(); - - if (p->flags & PF_NO_SETAFFINITY) { - retval = -EINVAL; - goto out_put_task; - } + if (p->flags & PF_NO_SETAFFINITY) + return -EINVAL; if (!check_same_owner(p)) { - rcu_read_lock(); - if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) { - rcu_read_unlock(); - retval = -EPERM; - goto out_put_task; - } - rcu_read_unlock(); + guard(rcu)(); + if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) + return -EPERM; } retval = security_task_setscheduler(p); if (retval) - goto out_put_task; + return retval; /* * With non-SMP configs, user_cpus_ptr/user_mask isn't used and @@ -8300,8 +8285,7 @@ long sched_setaffinity(pid_t pid, const if (user_mask) { cpumask_copy(user_mask, in_mask); } else if (IS_ENABLED(CONFIG_SMP)) { - retval = -ENOMEM; - goto out_put_task; + return -ENOMEM; } ac = (struct affinity_context){ @@ -8313,8 +8297,6 @@ long sched_setaffinity(pid_t pid, const retval = __sched_setaffinity(p, &ac); kfree(ac.user_mask); -out_put_task: - put_task_struct(p); return retval; } @@ -8356,28 +8338,21 @@ SYSCALL_DEFINE3(sched_setaffinity, pid_t long sched_getaffinity(pid_t pid, struct cpumask *mask) { struct task_struct *p; - unsigned long flags; int retval; - rcu_read_lock(); - - retval = -ESRCH; + guard(rcu)(); p = find_process_by_pid(pid); if (!p) - goto out_unlock; + return -ESRCH; retval = security_task_getscheduler(p); if (retval) - goto out_unlock; + return retval; - raw_spin_lock_irqsave(&p->pi_lock, flags); + guard(raw_spinlock_irqsave)(&p->pi_lock); cpumask_and(mask, &p->cpus_mask, cpu_active_mask); - raw_spin_unlock_irqrestore(&p->pi_lock, flags); -out_unlock: - rcu_read_unlock(); - - return retval; + return 0; } /**