From patchwork Fri Dec 7 09:31:33 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 10717741 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id EA12314E2 for ; Fri, 7 Dec 2018 09:31:43 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D79B72E6F7 for ; Fri, 7 Dec 2018 09:31:43 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id CB4202E72B; Fri, 7 Dec 2018 09:31:43 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 23BDD2E6F7 for ; Fri, 7 Dec 2018 09:31:43 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 0D1CC6E6F0; Fri, 7 Dec 2018 09:31:42 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mail-ed1-x544.google.com (mail-ed1-x544.google.com [IPv6:2a00:1450:4864:20::544]) by gabe.freedesktop.org (Postfix) with ESMTPS id CD9E16E6F0 for ; Fri, 7 Dec 2018 09:31:40 +0000 (UTC) Received: by mail-ed1-x544.google.com with SMTP id x30so3168286edx.2 for ; Fri, 07 Dec 2018 01:31:40 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=9r6QEonb0QVaWDJ+CdgD2wf4pog1OYVrSpjAnPjQmiA=; b=endA7jeyJgLj1cleMEgCHcpAw/JSwI+cuOEvEysMFue0Q7j4ZTTgP1GuYf3hBLO82A iKYXI+1j/t7CyeRqpMPFa1Kaxaun0Xo2qGGUTUJDKTB8/rDeYHrad7gE4PfszNTzZjdC 4DnY2/OYbLVmcrQBlJ6U+1lnZq75dUzVVrXvXybYA5f/6IIhc9tEvaTg3TK1oA1XmB5T dMTof2rO/7NdrI/PiOshJ5DO+HSpwyBL2S7VuBfjUuKLQMQPS7GkKrWyZeowu9y/Lori eHuBYi4Ac2IH1z9rotjlVe49onIissjA+MgH7To5wg5mU64H/acE4UJxrT5kJiYnCD7B SF8w== X-Gm-Message-State: AA+aEWZdiDgy5T2KymJUJQziVGI5YlitSHczdD8iUEb0vl6eP7W9AiQ0 xjE8HBjnggXDPJNTQibP7SOdkJ3kaX4= X-Google-Smtp-Source: AFSGD/X0F/4vJKow9apdZZk/N6b74szvfHQtDnVI2MkEpXwHEwZQHNmRYI7FIDzA063PHRfQmtARCQ== X-Received: by 2002:a50:cf41:: with SMTP id d1mr1592258edk.242.1544175099118; Fri, 07 Dec 2018 01:31:39 -0800 (PST) Received: from phenom.ffwll.local ([2a02:168:569e:0:3106:d637:d723:e855]) by smtp.gmail.com with ESMTPSA id t26sm915948eda.22.2018.12.07.01.31.37 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 07 Dec 2018 01:31:38 -0800 (PST) From: Daniel Vetter To: Intel Graphics Development Date: Fri, 7 Dec 2018 10:31:33 +0100 Message-Id: <20181207093133.15648-1-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.20.0.rc1 MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH] drivers/base: use a worker for sysfs unbind X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Daniel Vetter , Daniel Vetter Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Virus-Scanned: ClamAV using ClamSMTP Drivers might want to remove some sysfs files, which needs the same locks and ends up angering lockdep. Relevant snippet of the stack trace: kernfs_remove_by_name_ns+0x3b/0x80 bus_remove_driver+0x92/0xa0 acpi_video_unregister+0x24/0x40 i915_driver_unload+0x42/0x130 [i915] i915_pci_remove+0x19/0x30 [i915] pci_device_remove+0x36/0xb0 device_release_driver_internal+0x185/0x250 unbind_store+0xaf/0x180 kernfs_fop_write+0x104/0x190 I've stumbled over this because some new patches by Ram connect the snd-hda-intel unload (where we do use sysfs unbind) with the locking chains in the i915 unload code (but without creating a new loop), which upset our CI. But the bug is already there and can be easily reproduced by unbind i915 directly. No idea whether this is the correct place to fix this, should at least get CI happy again. Cc: Ramalingam C Signed-off-by: Daniel Vetter --- drivers/base/bus.c | 33 +++++++++++++++++++++++++++------ 1 file changed, 27 insertions(+), 6 deletions(-) diff --git a/drivers/base/bus.c b/drivers/base/bus.c index 8bfd27ec73d6..864412df86a9 100644 --- a/drivers/base/bus.c +++ b/drivers/base/bus.c @@ -174,22 +174,43 @@ static const struct kset_uevent_ops bus_uevent_ops = { static struct kset *bus_kset; +struct unbind_work { + struct work_struct work; + struct device *dev; +}; + +void unbind_work_fn(struct work_struct *work) +{ + struct unbind_work *unbind_work = + container_of(work, struct unbind_work, work); + + device_release_driver(unbind_work->dev); + put_device(unbind_work->dev); +} + /* Manually detach a device from its associated driver. */ static ssize_t unbind_store(struct device_driver *drv, const char *buf, size_t count) { struct bus_type *bus = bus_get(drv->bus); + struct unbind_work *unbind_work; struct device *dev; int err = -ENODEV; dev = bus_find_device_by_name(bus, NULL, buf); if (dev && dev->driver == drv) { - if (dev->parent && dev->bus->need_parent_lock) - device_lock(dev->parent); - device_release_driver(dev); - if (dev->parent && dev->bus->need_parent_lock) - device_unlock(dev->parent); - err = count; + unbind_work = kmalloc(sizeof(*unbind_work), GFP_KERNEL); + if (unbind_work) { + unbind_work->dev = dev; + get_device(dev); + INIT_WORK(&unbind_work->work, unbind_work_fn); + + schedule_work(&unbind_work->work); + + err = count; + } else { + err = -ENOMEM; + } } put_device(dev); bus_put(bus);