Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933370Ab3CSR3n (ORCPT ); Tue, 19 Mar 2013 13:29:43 -0400 Received: from mail-ia0-f178.google.com ([209.85.210.178]:53863 "EHLO mail-ia0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933214Ab3CSR3l (ORCPT ); Tue, 19 Mar 2013 13:29:41 -0400 MIME-Version: 1.0 In-Reply-To: References: Date: Tue, 19 Mar 2013 10:29:40 -0700 X-Google-Sender-Auth: 8wbvvB4kLOjmByEjOCgtfytNx7c Message-ID: Subject: Re: [PATCH] usb: Make USB persist default configurable From: Julius Werner To: Alan Stern Cc: Vincent Palatin , Greg Kroah-Hartman , LKML , linux-usb@vger.kernel.org, Lan Tianyu , Sameer Nanda , Luigi Semenzato Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1568 Lines: 28 > Yes, okay, that's true. If a new USB device is plugged in while the > lid is shut, and then the lid is opened very briefly, it's possible > that the system could suspend again before the new device's "persist" > attribute is updated. Does that case really matter? The device isn't > likely to be in use at that point. It does matter if the device will be used after the next resume, because that one would use the persist code. If there was a driver problem it would fail, and if it was a USB stick that is swapped with a different one of the same model, you could get file system corruption. I agree with you that buggy drivers should get fixed (and we are trying to do that as well), but at the same time we want to be able to have a system that can keep its policies at all times. We get a lot of USB problems (especially around suspend/resume), and we don't want to need to worry every time about which code path we hit and whether one of those race conditions could have something to do with it. I'm convinced that having this in the kernel is the cleanest solution for us, and I just thought it might be useful to standardize a mechanism for that (I don't really see the maintenance burden in that config option either, as the persist mechanism itself does not look like it was going to go away anytime soon). -- 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/