Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965220AbVKGV45 (ORCPT ); Mon, 7 Nov 2005 16:56:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965223AbVKGV44 (ORCPT ); Mon, 7 Nov 2005 16:56:56 -0500 Received: from smtp.osdl.org ([65.172.181.4]:65443 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S965230AbVKGV4y (ORCPT ); Mon, 7 Nov 2005 16:56:54 -0500 Date: Mon, 7 Nov 2005 13:54:35 -0800 (PST) From: Linus Torvalds To: Greg KH cc: linas , linux-sparse@vger.kernel.org, Paul Mackerras , linuxppc64-dev@ozlabs.org, johnrose@austin.ibm.com, linux-pci@atrey.karlin.mff.cuni.cz, bluesmoke-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/7]: PCI revised (2) [PATCH 16/42]: PCI: PCI Error reporting callbacks In-Reply-To: <20051107213729.GA24700@kroah.com> Message-ID: References: <20051103235918.GA25616@mail.gnucash.org> <20051104005035.GA26929@mail.gnucash.org> <20051105061114.GA27016@kroah.com> <17262.37107.857718.184055@cargo.ozlabs.ibm.com> <20051107175541.GB19593@austin.ibm.com> <20051107182727.GD18861@kroah.com> <20051107195727.GF19593@austin.ibm.com> <20051107200352.GB22524@kroah.com> <20051107212128.GH19593@austin.ibm.com> <20051107213729.GA24700@kroah.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1750 Lines: 39 On Mon, 7 Nov 2005, Greg KH wrote: > > > enum pci_channel_state { > > - pci_channel_io_normal = 0, /* I/O channel is in normal state */ > > - pci_channel_io_frozen = 1, /* I/O to channel is blocked */ > > - pci_channel_io_perm_failure, /* PCI card is dead */ > > + pci_channel_io_normal = (__force pci_channel_state_t) 0, /* I/O channel is in normal state */ > > + pci_channel_io_frozen = (__force pci_channel_state_t) 1, /* I/O to channel is blocked */ > > + pci_channel_io_perm_failure = (__force pci_channel_state_t) 2, /* PCI card is dead */ > > }; > > You don't have to use an enum anymore, just use a #define. The enum works fine, though, and has less namespace pollution than a #define, so sometimes an enum can be preferred. HOWEVER. For sanity, if possible please avoid using the value "0". It's magic for __bitwise, in that a zero is always acceptable as a bitwise thing (which makes sense if you think of bitwise as being about bits: the zero representation is totally independent of any bit ordering). So it's better to start counting from 1 if possible. > Sparse developers, I see code in the kernel that that does both > (__force foo_t) and (foo_t __force). Which one is correct? sparse doesn't care. Whatever scans better for humans. Attributes like "force" parse the same way things like "const" and "volatile" parses, and while most people _tend_ to write "const int", it's not incorrect to write "int const". Same with "__attribute__((force))", aka __force. Linus - 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/