From nobody Thu Apr 2 19:55:01 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 EE306C32771 for ; Wed, 21 Sep 2022 13:23:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230345AbiIUNXf (ORCPT ); Wed, 21 Sep 2022 09:23:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43594 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230107AbiIUNXW (ORCPT ); Wed, 21 Sep 2022 09:23:22 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8C17293535 for ; Wed, 21 Sep 2022 06:23:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1663766600; h=from:from: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=8doRy3Tl9duFaqpT4x4KIGruvUlzYzIUxZbJ5Ad4nHc=; b=QoKTnbCfkdPaqn63B67ugMXS8goJAhCLvvjVXKDP8fKM/wpTnU+Rje1tskAPPoMAAYiDPM a3AzOQKzfqct3+K+F4Q0gxz+IhaA+Ib/VjU8a2mm6y/YWL62oySPaBplD7q18NPb0wg94U /DIYfKhzdq9KqBAnvRqrDeSkYR0YwjQ= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-479-nOCfVYZRN2SReAZKKgUxyQ-1; Wed, 21 Sep 2022 09:23:16 -0400 X-MC-Unique: nOCfVYZRN2SReAZKKgUxyQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id D265487B2A4; Wed, 21 Sep 2022 13:23:15 +0000 (UTC) Received: from llong.com (dhcp-17-215.bos.redhat.com [10.18.17.215]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9AD3839D7C; Wed, 21 Sep 2022 13:23:15 +0000 (UTC) From: Waiman Long To: Peter Zijlstra , Ingo Molnar , Will Deacon , Boqun Feng , Steven Rostedt Cc: linux-kernel@vger.kernel.org, Waiman Long Subject: [PATCH 2/2] tracing: Use proper do_arch_spin_lock() API Date: Wed, 21 Sep 2022 09:21:52 -0400 Message-Id: <20220921132152.1622616-3-longman@redhat.com> In-Reply-To: <20220921132152.1622616-1-longman@redhat.com> References: <20220921132152.1622616-1-longman@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" It was found that some tracing functions acquire a arch_spinlock_t with preemption and irqs enabled. That can be problematic in case preemption happens after acquiring the lock. Use the proper do_arch_spin_lock() API with preemption disabled to make sure that this won't happen unless it is obvious that either preemption or irqs has been disabled . Signed-off-by: Waiman Long --- kernel/trace/trace.c | 52 ++++++++++++++++++++------------------------ 1 file changed, 24 insertions(+), 28 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index d3005279165d..cbb8520842ad 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1193,12 +1193,12 @@ void *tracing_cond_snapshot_data(struct trace_array= *tr) { void *cond_data =3D NULL; =20 - arch_spin_lock(&tr->max_lock); + do_arch_spin_lock(&tr->max_lock); =20 if (tr->cond_snapshot) cond_data =3D tr->cond_snapshot->cond_data; =20 - arch_spin_unlock(&tr->max_lock); + do_arch_spin_unlock(&tr->max_lock); =20 return cond_data; } @@ -1334,9 +1334,9 @@ int tracing_snapshot_cond_enable(struct trace_array *= tr, void *cond_data, goto fail_unlock; } =20 - arch_spin_lock(&tr->max_lock); + do_arch_spin_lock(&tr->max_lock); tr->cond_snapshot =3D cond_snapshot; - arch_spin_unlock(&tr->max_lock); + do_arch_spin_unlock(&tr->max_lock); =20 mutex_unlock(&trace_types_lock); =20 @@ -1363,7 +1363,7 @@ int tracing_snapshot_cond_disable(struct trace_array = *tr) { int ret =3D 0; =20 - arch_spin_lock(&tr->max_lock); + do_arch_spin_lock(&tr->max_lock); =20 if (!tr->cond_snapshot) ret =3D -EINVAL; @@ -1372,7 +1372,7 @@ int tracing_snapshot_cond_disable(struct trace_array = *tr) tr->cond_snapshot =3D NULL; } =20 - arch_spin_unlock(&tr->max_lock); + do_arch_spin_unlock(&tr->max_lock); =20 return ret; } @@ -1819,7 +1819,7 @@ update_max_tr(struct trace_array *tr, struct task_str= uct *tsk, int cpu, return; } =20 - arch_spin_lock(&tr->max_lock); + do_arch_spin_lock(&tr->max_lock); =20 /* Inherit the recordable setting from array_buffer */ if (ring_buffer_record_is_set_on(tr->array_buffer.buffer)) @@ -1836,7 +1836,7 @@ update_max_tr(struct trace_array *tr, struct task_str= uct *tsk, int cpu, __update_max_tr(tr, tsk, cpu); =20 out_unlock: - arch_spin_unlock(&tr->max_lock); + do_arch_spin_unlock(&tr->max_lock); } =20 /** @@ -1862,7 +1862,7 @@ update_max_tr_single(struct trace_array *tr, struct t= ask_struct *tsk, int cpu) return; } =20 - arch_spin_lock(&tr->max_lock); + do_arch_spin_lock(&tr->max_lock); =20 ret =3D ring_buffer_swap_cpu(tr->max_buffer.buffer, tr->array_buffer.buff= er, cpu); =20 @@ -1880,7 +1880,7 @@ update_max_tr_single(struct trace_array *tr, struct t= ask_struct *tsk, int cpu) WARN_ON_ONCE(ret && ret !=3D -EAGAIN && ret !=3D -EBUSY); =20 __update_max_tr(tr, tsk, cpu); - arch_spin_unlock(&tr->max_lock); + do_arch_spin_unlock(&tr->max_lock); } #endif /* CONFIG_TRACER_MAX_TRACE */ =20 @@ -2413,7 +2413,7 @@ static int trace_save_cmdline(struct task_struct *tsk) * nor do we want to disable interrupts, * so if we miss here, then better luck next time. */ - if (!arch_spin_trylock(&trace_cmdline_lock)) + if (!do_arch_spin_trylock(&trace_cmdline_lock)) return 0; =20 idx =3D savedcmd->map_pid_to_cmdline[tpid]; @@ -2427,7 +2427,7 @@ static int trace_save_cmdline(struct task_struct *tsk) savedcmd->map_cmdline_to_pid[idx] =3D tsk->pid; set_cmdline(idx, tsk->comm); =20 - arch_spin_unlock(&trace_cmdline_lock); + do_arch_spin_unlock(&trace_cmdline_lock); =20 return 1; } @@ -2461,13 +2461,11 @@ static void __trace_find_cmdline(int pid, char comm= []) =20 void trace_find_cmdline(int pid, char comm[]) { - preempt_disable(); - arch_spin_lock(&trace_cmdline_lock); + do_arch_spin_lock(&trace_cmdline_lock); =20 __trace_find_cmdline(pid, comm); =20 - arch_spin_unlock(&trace_cmdline_lock); - preempt_enable(); + do_arch_spin_unlock(&trace_cmdline_lock); } =20 static int *trace_find_tgid_ptr(int pid) @@ -5829,8 +5827,7 @@ static void *saved_cmdlines_start(struct seq_file *m,= loff_t *pos) void *v; loff_t l =3D 0; =20 - preempt_disable(); - arch_spin_lock(&trace_cmdline_lock); + do_arch_spin_lock(&trace_cmdline_lock); =20 v =3D &savedcmd->map_cmdline_to_pid[0]; while (l <=3D *pos) { @@ -5844,8 +5841,7 @@ static void *saved_cmdlines_start(struct seq_file *m,= loff_t *pos) =20 static void saved_cmdlines_stop(struct seq_file *m, void *v) { - arch_spin_unlock(&trace_cmdline_lock); - preempt_enable(); + do_arch_spin_unlock(&trace_cmdline_lock); } =20 static int saved_cmdlines_show(struct seq_file *m, void *v) @@ -5890,9 +5886,9 @@ tracing_saved_cmdlines_size_read(struct file *filp, c= har __user *ubuf, char buf[64]; int r; =20 - arch_spin_lock(&trace_cmdline_lock); + do_arch_spin_lock(&trace_cmdline_lock); r =3D scnprintf(buf, sizeof(buf), "%u\n", savedcmd->cmdline_num); - arch_spin_unlock(&trace_cmdline_lock); + do_arch_spin_unlock(&trace_cmdline_lock); =20 return simple_read_from_buffer(ubuf, cnt, ppos, buf, r); } @@ -5917,10 +5913,10 @@ static int tracing_resize_saved_cmdlines(unsigned i= nt val) return -ENOMEM; } =20 - arch_spin_lock(&trace_cmdline_lock); + do_arch_spin_lock(&trace_cmdline_lock); savedcmd_temp =3D savedcmd; savedcmd =3D s; - arch_spin_unlock(&trace_cmdline_lock); + do_arch_spin_unlock(&trace_cmdline_lock); free_saved_cmdlines_buffer(savedcmd_temp); =20 return 0; @@ -6373,10 +6369,10 @@ int tracing_set_tracer(struct trace_array *tr, cons= t char *buf) =20 #ifdef CONFIG_TRACER_SNAPSHOT if (t->use_max_tr) { - arch_spin_lock(&tr->max_lock); + do_arch_spin_lock(&tr->max_lock); if (tr->cond_snapshot) ret =3D -EBUSY; - arch_spin_unlock(&tr->max_lock); + do_arch_spin_unlock(&tr->max_lock); if (ret) goto out; } @@ -7436,10 +7432,10 @@ tracing_snapshot_write(struct file *filp, const cha= r __user *ubuf, size_t cnt, goto out; } =20 - arch_spin_lock(&tr->max_lock); + do_arch_spin_lock(&tr->max_lock); if (tr->cond_snapshot) ret =3D -EBUSY; - arch_spin_unlock(&tr->max_lock); + do_arch_spin_unlock(&tr->max_lock); if (ret) goto out; =20 --=20 2.31.1