Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753576Ab3IJRMi (ORCPT ); Tue, 10 Sep 2013 13:12:38 -0400 Received: from mail-bk0-f48.google.com ([209.85.214.48]:44033 "EHLO mail-bk0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752428Ab3IJRMg (ORCPT ); Tue, 10 Sep 2013 13:12:36 -0400 MIME-Version: 1.0 X-Originating-IP: [89.2.206.189] In-Reply-To: References: <1378831050-22262-1-git-send-email-teg@jklm.no> From: Tom Gundersen Date: Tue, 10 Sep 2013 19:12:12 +0200 Message-ID: Subject: Re: [PATCH] usb: ohci/uhci - add soft dependencies on ehci_hcd To: Alan Stern Cc: linux-usb@vger.kernel.org, LKML , "linux-modules@vger.kernel.org" , Greg Kroah-Hartman Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3430 Lines: 85 Hi Alan, On Tue, Sep 10, 2013 at 7:02 PM, Alan Stern wrote: > On Tue, 10 Sep 2013, Tom Gundersen wrote: > >> Support for specifying soft dependencies in the modules themselves was >> introduced in commit 7cb14ba. >> >> In Arch we have always been shipping a module.d(5) fragment ordering ohci/uhci >> after ehci. If this ordering is really necessary, it would be great to move it >> to the kernel and getting the correct fragment generated by depmod. > > The ordering is more of a recommendation than a necessity. Systems > should work oksy if the modules are loaded in the wrong order. > > The only issue if the drivers are loaded in the wrong order is that > full- and low-speed devices will end up being detected and enumerated > twice, with a disconnection in between. This can result in > disconcerting messages appearing in the system log. > > In theory, it is possible for a problem to arise. For example, suppose > a full-speed flash drive is plugged in when the system starts up. > When uhci-hcd or ohci-hcd gets loaded, the drive will be detected and > it may even be mounted. Then when ehci-hcd loads, the drive will get > disconnected and reconnected. Any open file references to the original > mount will be orphaned. Thanks for the explanation. Sounds to me that a softdep is indeed appropriate: // The softdep command allows you to specify soft, or optional, module dependencies. modulename can be used without these optional modules installed, but usually with some features missing. For example, a driver for a storage HBA might require another module be loaded in order to use management features. pre-deps and post-deps modules are lists of names and/or aliases of other modules that modprobe will attempt to install (or remove) in order before and after the main module given in the modulename argument. // >> Signed-off-by: Tom Gundersen >> Cc: Alan Stern >> Cc: Greg Kroah-Hartman >> --- >> drivers/usb/host/ohci-hcd.c | 1 + >> drivers/usb/host/uhci-hcd.c | 1 + >> 2 files changed, 2 insertions(+) >> >> diff --git a/drivers/usb/host/ohci-hcd.c b/drivers/usb/host/ohci-hcd.c >> index 8f6b695..783b50a 100644 >> --- a/drivers/usb/host/ohci-hcd.c >> +++ b/drivers/usb/host/ohci-hcd.c >> @@ -1171,6 +1171,7 @@ EXPORT_SYMBOL_GPL(ohci_init_driver); >> MODULE_AUTHOR (DRIVER_AUTHOR); >> MODULE_DESCRIPTION(DRIVER_DESC); >> MODULE_LICENSE ("GPL"); >> +MODULE_SOFTDEP("pre: ehci_hcd"); >> >> #if defined(CONFIG_ARCH_SA1100) && defined(CONFIG_SA1111) >> #include "ohci-sa1111.c" >> diff --git a/drivers/usb/host/uhci-hcd.c b/drivers/usb/host/uhci-hcd.c >> index 4a86b63..c2babf3 100644 >> --- a/drivers/usb/host/uhci-hcd.c >> +++ b/drivers/usb/host/uhci-hcd.c >> @@ -937,3 +937,4 @@ module_exit(uhci_hcd_cleanup); >> MODULE_AUTHOR(DRIVER_AUTHOR); >> MODULE_DESCRIPTION(DRIVER_DESC); >> MODULE_LICENSE("GPL"); >> +MODULE_SOFTDEP("pre: ehci_hcd"); > > Where is MODULE_SOFTDEP defined? It isn't mentioned in any .h files in > my kernel tree. https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/include/linux/module.h#n104 Cheers, Tom -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/