From mboxrd@z Thu Jan 1 00:00:00 1970 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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 4925AC282C8 for ; Mon, 28 Jan 2019 16:31:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 23D6D20663 for ; Mon, 28 Jan 2019 16:31:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390550AbfA1QbU (ORCPT ); Mon, 28 Jan 2019 11:31:20 -0500 Received: from mga09.intel.com ([134.134.136.24]:36976 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729376AbfA1QbQ (ORCPT ); Mon, 28 Jan 2019 11:31:16 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 28 Jan 2019 08:31:12 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.56,534,1539673200"; d="scan'208";a="133802915" Received: from ahduyck-desk1.jf.intel.com ([10.7.198.76]) by orsmga001.jf.intel.com with ESMTP; 28 Jan 2019 08:31:11 -0800 Message-ID: <8a28b7eafc81f693fa1a580c70a1f9465818eb86.camel@linux.intel.com> Subject: Re: [RFC PATCH v2] async: Add cmdline option to specify drivers to be async probed From: Alexander Duyck To: Feng Tang , Greg Kroah-Hartman , "Rafael J . Wysocki" , Arjan van de Ven , linux-kernel@vger.kernel.org Date: Mon, 28 Jan 2019 08:31:11 -0800 In-Reply-To: <1548638416-96859-1-git-send-email-feng.tang@intel.com> References: <1548638416-96859-1-git-send-email-feng.tang@intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 (3.28.5-2.fc28) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2019-01-28 at 09:20 +0800, Feng Tang wrote: > Asynchronous driver probing can help much on kernel fastboot, and > this option can provide a flexible way to optimize and quickly verify > async driver probe. > > Also it will help in below cases: > * Some driver actually covers several families of HWs, some of which > could use async probing while others don't. So we can't simply > turn on the PROBE_PREFER_ASYNCHRONOUS flag in driver, but use this > cmdline option, like igb driver async patch discussed at > https://www.spinics.net/lists/netdev/msg545986.html > > * For SOC (System on Chip) with multiple spi or i2c controllers, most > of the slave spi/i2c devices will be assigned with fixed controller > number, while async probing may make those controllers get different > index for each boot, which prevents those controller drivers to be > async probed. For platforms not using these spi/i2c slave devices, > they can use this cmdline option to benefit from the async probing. > > Suggested-by: Alexander Duyck > Signed-off-by: Feng Tang > --- > drivers/base/dd.c | 23 +++++++++++++++++++++++ > 1 file changed, 23 insertions(+) > > diff --git a/drivers/base/dd.c b/drivers/base/dd.c > index 8ac10af..cfa704a 100644 > --- a/drivers/base/dd.c > +++ b/drivers/base/dd.c > @@ -57,6 +57,10 @@ static atomic_t deferred_trigger_count = ATOMIC_INIT(0); > static struct dentry *deferred_devices; > static bool initcalls_done; > > +/* Save the async probe drivers' name from kernel cmdline */ > +#define ASYNC_DRV_NAMES_MAX_LEN 256 > +static char async_probe_drv_names[ASYNC_DRV_NAMES_MAX_LEN]; > + > /* > * In some cases, like suspend to RAM or hibernation, It might be reasonable > * to prohibit probing of devices as it could be unsafe. > @@ -674,8 +678,27 @@ int driver_probe_device(struct device_driver *drv, struct device *dev) > return ret; > } > > +static inline bool cmdline_requested_async_probing(const char *drv_name) > +{ > + return parse_option_str(async_probe_drv_names, drv_name); > +} > + > +/* The format is like driver_async_probe=drv_name1,drv_name2,drv_name3 */ > +static int __init save_async_options(char *buf) > +{ > + if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN) > + printk(KERN_WARNING "Too long list for async_probe_drv_names!"); > + > + strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN); > + return 0; > +} > +__setup("driver_async_probe=", save_async_options); > + > bool driver_allows_async_probing(struct device_driver *drv) > { > + if (cmdline_requested_async_probing(drv->name)) > + return true; > + This piece still should be moved. Ideally it should be down in the "default" case area we use to determine if the module parameter async_probe was used or not. Where you currently have this will overrride the driver behavior if it absolutely cannot use an asynchronous probe. > switch (drv->probe_type) { > case PROBE_PREFER_ASYNCHRONOUS: > return true;