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    SubjectRe: [PATCH 1/5] drivercore: add new error value for deferred probe
    On Wed, Oct 12, 2011 at 11:48:23AM +0530, G, Manjunath Kondaiah wrote:
    > On Sun, Oct 09, 2011 at 06:06:56PM -0700, Greg KH wrote:
    > > On Sun, Oct 09, 2011 at 04:59:31PM -0600, Grant Likely wrote:
    > > > On Fri, Oct 7, 2011 at 6:12 PM, Greg KH <greg@kroah.com> wrote:
    > > > > On Fri, Oct 07, 2011 at 07:28:33PM -0400, Valdis.Kletnieks@vt.edu wrote:
    > > > >> On Fri, 07 Oct 2011 16:12:45 MDT, Grant Likely said:
    > > > >> > On Fri, Oct 7, 2011 at 12:43 AM, Greg KH <greg@kroah.com> wrote:
    > > > >> > > On Fri, Oct 07, 2011 at 10:33:06AM +0500, G, Manjunath Kondaiah wrote:
    > > > >>
    > > > >> > >> +#define EPROBE_DEFER 517     /* restart probe again after some time */
    > > > >> > >
    > > > >> > > Can we really do this?
    > > > >>
    > > > >> > According to Arnd, yes this is okay.
    > > > >>
    > > > >> > >  Isn't this some user/kernel api here?
    > > > >>
    > > > >> > > What's wrong with just "overloading" on top of an existing error code?
    > > > >> > > Surely one of the other 516 types could be used here, right?
    > > > >>
    > > > >> > overloading makes it really hard to find the users at a later date.
    > > > >>
    > > > >> Would proposing '#define EPROBE_DEFER EAGAIN' be acceptable to everybody? That
    > > > >> would allow overloading EAGAIN, but still make it easy to tell the usages apart
    > > > >> if we need to separate them later...
    > > > >
    > > > > Yes, please do that, it is what USB does for it's internal error code
    > > > > handling.
    > > >
    > > > Really? When we've only currently used approximately 2^9 of a 2^31
    > > > numberspace? I'm fine with making sure that the number doesn't show
    > > > up in the userspace headers, but it makes no sense to overload the
    > > > #defines. Particularly so in this case where it isn't feasible to
    > > > audit every driver to figure out what probe might possibly return. It
    > > > is well within the realm of possibility that existing drivers are
    > > > already returning -EAGAIN.
    > >
    > > I doubt they are, but you are right, it's really hard to tell.
    > >
    > > > Besides; linux/errno.h *already* has linux-internal error codes that
    > > > do not get exported out to userspace. There is an #ifdef __KERNEL__
    > > > block around ERESTARTSYS through EIOCBRETRY which is filtered out when
    > > > exporting headers. I can't see any possible reason why we wouldn't
    > > > add Linux internal error codes here.
    > >
    > > As long as it stays internal, that's fine, I was worried that this would
    > > be exported to userspace.
    > >
    > > Alan, still object to this?
    >
    > I hope no one has objections to use EPROBE_DEFER

    I say go with that value. If Alan still objects, then he will speak up.

    g.
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