From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8E27E7462 for ; Fri, 18 Apr 2025 16:38:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744994312; cv=none; b=ltyxeX+tFgdGoZdm0aWH4/mWIvvKxI1bgqbmOUiBfPDTZKKNhbWWU6ErFfgfSt59Uk0WUSuToQiKV9CUFDZPhtss7n5gwHg9LLwevW3RmQuIEnpfe04TKjzeHHL4oBx3FToxlqbZAxZMQ49TfmC1mpXv4ybFjBB63NThVOHiXHg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744994312; c=relaxed/simple; bh=q2jCv4fj42tMGcSPxWIaka9P/+dS4gyig+acpdMrlSc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GkOEsXhbX+6fcYoeaZh98Kn4eGht9vWPVF+5oiNH/L3rz0jlmGojUVTOZXICZMwrFexMrKgOLrpGOtdb5IIwITgAmGeThboihH9/08FhojEHEHmjLfmQFPW5hagQH1r5oARrZghCwQQNVUXd+XEzkpwz+r1qaFLPg5DIWsRgz3U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=UA82JnEk; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="UA82JnEk" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1744994309; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5wkWQXgWjr4tyJneJ8rrzbQKv/kR8kzwxaaf7vr4i4g=; b=UA82JnEk3/KE92aZGMkjibpEJTBIUh1KHEMvZ05uIZgDtPBC5hd1XZQNVgKcMeVXwQv0Dp wXlBzYEELue0AOh3km6YcnNDXZVudpptJxM5ynNYKsJZ2aEkfPGq4u1n9iIh2vG998387d JPvd4RPyWD2o6tIQqvamk3T1fCLNqxk= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-168-Src3OM0DOsG-FLZxIrKiPg-1; Fri, 18 Apr 2025 12:38:24 -0400 X-MC-Unique: Src3OM0DOsG-FLZxIrKiPg-1 X-Mimecast-MFC-AGG-ID: Src3OM0DOsG-FLZxIrKiPg_1744994303 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (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 mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 11D891956086; Fri, 18 Apr 2025 16:38:23 +0000 (UTC) Received: from localhost (unknown [10.72.116.50]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 05D8119560A3; Fri, 18 Apr 2025 16:38:21 +0000 (UTC) From: Ming Lei To: Jens Axboe , linux-block@vger.kernel.org Cc: Nilay Shroff , Shinichiro Kawasaki , =?UTF-8?q?Thomas=20Hellstr=C3=B6m?= , Christoph Hellwig , Ming Lei Subject: [PATCH V2 15/20] block: fail to show/store elevator sysfs attribute if elevator is dying Date: Sat, 19 Apr 2025 00:36:56 +0800 Message-ID: <20250418163708.442085-16-ming.lei@redhat.com> In-Reply-To: <20250418163708.442085-1-ming.lei@redhat.com> References: <20250418163708.442085-1-ming.lei@redhat.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Prepare for moving elv_register[unregister]_queue out of elevator_lock & queue freezing, so we may have to call elv_unregister_queue() after elevator ->exit() is called, then there is small window for user to run into ->show()/store(), and user-after-free can be caused. Fail to show/store elevator sysfs attribute if elevator is dying by adding one new flag of ELEVATOR_FLAG_DYNG, which is protected by elevator ->sysfs_lock. Signed-off-by: Ming Lei --- block/blk-mq-sched.c | 1 + block/elevator.c | 10 ++++++++-- block/elevator.h | 1 + 3 files changed, 10 insertions(+), 2 deletions(-) diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c index 336a15ffecfa..55a0fd105147 100644 --- a/block/blk-mq-sched.c +++ b/block/blk-mq-sched.c @@ -551,5 +551,6 @@ void blk_mq_exit_sched(struct request_queue *q, struct elevator_queue *e) if (e->type->ops.exit_sched) e->type->ops.exit_sched(e); blk_mq_sched_tags_teardown(q, flags); + set_bit(ELEVATOR_FLAG_DYING, &q->elevator->flags); q->elevator = NULL; } diff --git a/block/elevator.c b/block/elevator.c index 568457e01d28..16171ea92f80 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -422,7 +422,10 @@ elv_attr_show(struct kobject *kobj, struct attribute *attr, char *page) e = container_of(kobj, struct elevator_queue, kobj); mutex_lock(&e->sysfs_lock); - error = e->type ? entry->show(e, page) : -ENOENT; + if (test_bit(ELEVATOR_FLAG_DYING, &e->flags)) + error = -ENODEV; + else + error = e->type ? entry->show(e, page) : -ENOENT; mutex_unlock(&e->sysfs_lock); return error; } @@ -440,7 +443,10 @@ elv_attr_store(struct kobject *kobj, struct attribute *attr, e = container_of(kobj, struct elevator_queue, kobj); mutex_lock(&e->sysfs_lock); - error = e->type ? entry->store(e, page, length) : -ENOENT; + if (test_bit(ELEVATOR_FLAG_DYING, &e->flags)) + error = -ENODEV; + else + error = e->type ? entry->store(e, page, length) : -ENOENT; mutex_unlock(&e->sysfs_lock); return error; } diff --git a/block/elevator.h b/block/elevator.h index e74e27dd6586..16d8888fa2b2 100644 --- a/block/elevator.h +++ b/block/elevator.h @@ -121,6 +121,7 @@ struct elevator_queue }; #define ELEVATOR_FLAG_REGISTERED 0 +#define ELEVATOR_FLAG_DYING 1 /* Holding context data for changing elevator */ struct elv_change_ctx { -- 2.47.0