From patchwork Tue Jun 15 13:35:13 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 12321665 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DAA05C49EAB for ; Tue, 15 Jun 2021 13:40:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C046C61474 for ; Tue, 15 Jun 2021 13:40:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231854AbhFONmR (ORCPT ); Tue, 15 Jun 2021 09:42:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57094 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231540AbhFONly (ORCPT ); Tue, 15 Jun 2021 09:41:54 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9D0E8C0613A3; Tue, 15 Jun 2021 06:39:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=nK9oYryAhBF0mkiA41xiL6v1OSc3YceHNrs1K8YxY9E=; b=Xq4JVrkj676LAOM7cPpq6Lf5wA nuUoDANT46FNkT3CtVRD+2r+B/xjtu5YqCvwEtp+/n+P6wP8kU4YydxwSu0y3AZfvMEaoHYTEoUVG PaVEF+fWJtsG+wOP3+XIpT3N0ksJXG01Jc5F0wDMqPLSGBS/J97hchCpCHhu1dBWtSgCaDkLwJYCv uGviFR2/+ojWaqQ/S5C9uPodZYHNPYpeNiJxGLH/U80ap85ulAcvzCj7eo2ZP0dYrss+NZIAgBQhB jMs+VoXa6Pmua3zVzFHu7WWC109hfwffUs+mH/VnGO86LH4gN38e7hOvpyTVNS/YJXCo/Sriipl3k UVfnqU/Q==; Received: from [2001:4bb8:19b:fdce:9045:1e63:20f0:ca9] (helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1lt9Gg-006pCz-3W; Tue, 15 Jun 2021 13:38:23 +0000 From: Christoph Hellwig To: Greg Kroah-Hartman , Jason Gunthorpe , Alex Williamson , Kirti Wankhede Cc: David Airlie , Tony Krowiak , Christian Borntraeger , Cornelia Huck , Jonathan Corbet , Daniel Vetter , dri-devel@lists.freedesktop.org, Vasily Gorbik , Heiko Carstens , intel-gfx@lists.freedesktop.org, Jani Nikula , Jason Herne , Joonas Lahtinen , kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-s390@vger.kernel.org, Halil Pasic , "Rafael J. Wysocki" , Rodrigo Vivi Subject: [PATCH 04/10] driver core: Don't return EPROBE_DEFER to userspace during sysfs bind Date: Tue, 15 Jun 2021 15:35:13 +0200 Message-Id: <20210615133519.754763-5-hch@lst.de> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210615133519.754763-1-hch@lst.de> References: <20210615133519.754763-1-hch@lst.de> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org EPROBE_DEFER is an internal kernel error code and it should not be leaked to userspace via the bind_store() sysfs. Userspace doesn't have this constant and cannot understand it. Further, it doesn't really make sense to have userspace trigger a deferred probe via bind_store(), which could eventually succeed, while simultaneously returning an error back. Resolve this by splitting driver_probe_device so that the version used by the sysfs binding that turns EPROBE_DEFER into -EAGAIN, while the one used for internally binding keeps the error code, and calls driver_deferred_probe_add where needed. This also allows to nicely split out the defer_all_probes / probe_count checks so that they actually allow for full device_{block,unblock}_probing protection while not bothering the sysfs bind case. Signed-off-by: Christoph Hellwig Reviewed-by: Greg Kroah-Hartman Reviewed-by: Cornelia Huck --- drivers/base/dd.c | 78 +++++++++++++++++++++++++---------------------- 1 file changed, 42 insertions(+), 36 deletions(-) diff --git a/drivers/base/dd.c b/drivers/base/dd.c index 25341f52198c..7d54bae52a8d 100644 --- a/drivers/base/dd.c +++ b/drivers/base/dd.c @@ -491,15 +491,6 @@ EXPORT_SYMBOL_GPL(device_bind_driver); static atomic_t probe_count = ATOMIC_INIT(0); static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue); -static void driver_deferred_probe_add_trigger(struct device *dev, - int local_trigger_count) -{ - driver_deferred_probe_add(dev); - /* Did a trigger occur while probing? Need to re-trigger if yes */ - if (local_trigger_count != atomic_read(&deferred_trigger_count)) - driver_deferred_probe_trigger(); -} - static ssize_t state_synced_show(struct device *dev, struct device_attribute *attr, char *buf) { @@ -547,10 +538,9 @@ static int call_driver_probe(struct device *dev, struct device_driver *drv) static int really_probe(struct device *dev, struct device_driver *drv) { - int local_trigger_count = atomic_read(&deferred_trigger_count); bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) && !drv->suppress_bind_attrs; - int ret = -EPROBE_DEFER, probe_ret = 0; + int ret, probe_ret = 0; if (defer_all_probes) { /* @@ -559,17 +549,13 @@ static int really_probe(struct device *dev, struct device_driver *drv) * wait_for_device_probe() right after that to avoid any races. */ dev_dbg(dev, "Driver %s force probe deferral\n", drv->name); - driver_deferred_probe_add(dev); - return ret; + return -EPROBE_DEFER; } ret = device_links_check_suppliers(dev); - if (ret == -EPROBE_DEFER) - driver_deferred_probe_add_trigger(dev, local_trigger_count); if (ret) return ret; - atomic_inc(&probe_count); pr_debug("bus: '%s': %s: probing driver %s with device %s\n", drv->bus->name, __func__, drv->name, dev_name(dev)); if (!list_empty(&dev->devres_head)) { @@ -681,11 +667,7 @@ static int really_probe(struct device *dev, struct device_driver *drv) dev->pm_domain->dismiss(dev); pm_runtime_reinit(dev); dev_pm_set_driver_flags(dev, 0); - if (probe_ret == -EPROBE_DEFER) - driver_deferred_probe_add_trigger(dev, local_trigger_count); done: - atomic_dec(&probe_count); - wake_up_all(&probe_waitqueue); return ret; } @@ -739,21 +721,7 @@ void wait_for_device_probe(void) } EXPORT_SYMBOL_GPL(wait_for_device_probe); -/** - * driver_probe_device - attempt to bind device & driver together - * @drv: driver to bind a device to - * @dev: device to try to bind to the driver - * - * This function returns -ENODEV if the device is not registered, -EBUSY if it - * already has a driver, 0 if the device is bound successfully and a positive - * (inverted) error code for failures from the ->probe method. - * - * This function must be called with @dev lock held. When called for a - * USB interface, @dev->parent lock must be held as well. - * - * If the device has a parent, runtime-resume the parent before driver probing. - */ -static int driver_probe_device(struct device_driver *drv, struct device *dev) +static int __driver_probe_device(struct device_driver *drv, struct device *dev) { int ret = 0; @@ -784,6 +752,42 @@ static int driver_probe_device(struct device_driver *drv, struct device *dev) return ret; } +/** + * driver_probe_device - attempt to bind device & driver together + * @drv: driver to bind a device to + * @dev: device to try to bind to the driver + * + * This function returns -ENODEV if the device is not registered, -EBUSY if it + * already has a driver, 0 if the device is bound successfully and a positive + * (inverted) error code for failures from the ->probe method. + * + * This function must be called with @dev lock held. When called for a + * USB interface, @dev->parent lock must be held as well. + * + * If the device has a parent, runtime-resume the parent before driver probing. + */ +static int driver_probe_device(struct device_driver *drv, struct device *dev) +{ + int trigger_count = atomic_read(&deferred_trigger_count); + int ret; + + atomic_inc(&probe_count); + ret = __driver_probe_device(drv, dev); + if (ret == -EPROBE_DEFER || ret == EPROBE_DEFER) { + driver_deferred_probe_add(dev); + + /* + * Did a trigger occur while probing? Need to re-trigger if yes + */ + if (trigger_count != atomic_read(&deferred_trigger_count) && + !defer_all_probes) + driver_deferred_probe_trigger(); + } + atomic_dec(&probe_count); + wake_up_all(&probe_waitqueue); + return ret; +} + static inline bool cmdline_requested_async_probing(const char *drv_name) { return parse_option_str(async_probe_drv_names, drv_name); @@ -1051,12 +1055,14 @@ int device_driver_attach(struct device_driver *drv, struct device *dev) int ret; __device_driver_lock(dev, dev->parent); - ret = driver_probe_device(drv, dev); + ret = __driver_probe_device(drv, dev); __device_driver_unlock(dev, dev->parent); /* also return probe errors as normal negative errnos */ if (ret > 0) ret = -ret; + if (ret == -EPROBE_DEFER) + return -EAGAIN; return ret; }