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From: Ben Widawsky <ben.widawsky@intel.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Bjorn Helgaas <helgaas@kernel.org>,
	linux-cxl@vger.kernel.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux PCI <linux-pci@vger.kernel.org>,
	Linux ACPI <linux-acpi@vger.kernel.org>,
	Ira Weiny <ira.weiny@intel.com>,
	Vishal Verma <vishal.l.verma@intel.com>,
	"Kelley, Sean V" <sean.v.kelley@intel.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>
Subject: Re: [RFC PATCH 4/9] cxl/mem: Map memory device registers
Date: Mon, 23 Nov 2020 11:58:33 -0800	[thread overview]
Message-ID: <20201123195833.zeyhja6no6dkd32c@intel.com> (raw)
In-Reply-To: <CAPcyv4jJpvLErK8vBW-D2ZQASU0iJqFLRr7yDXB0kfGPrmi6xw@mail.gmail.com>

On 20-11-23 11:32:33, Dan Williams wrote:
> On Mon, Nov 23, 2020 at 11:20 AM Ben Widawsky <ben.widawsky@intel.com> wrote:
> [..]
> > > -ENXIO is fine with me.  I just don't see it as often so I don't
> > > really know what it is.
> > >
> > > Bjorn
> >
> > Dan, Bjorn, I did a fairly randomized look at various probe functions and ENODEV
> > seems to be more common. My sort of historical use has been
> > - ENODEV: General, couldn't establish device presence
> > - ENXIO: Device was there but something is totally misconfigured
> > - E*: A matching errno for exactly what went wrong
> >
> > My question though is, would it be useful to propagate the error up through
> > probe?
> 
> The error from probe becomes the modprobe exit code, or the write to
> the 'bind' attribute errno. So, it's a choice between "No such device
> or address", or "No such device". The "or address" mention makes a
> small bit more sense to me since the device is obviously present as it
> is visible in lspci, but either error code clearly indicates a driver
> problem so ENODEV is fine.
> 
> For the other error codes I think it would be confusing to return
> something like EINVAL from probe as that would be mistaken as an
> invalid argument to the modprobe without stracing to see that it came
> from the result of a sysfs write

Currently in this path there are 2 general reasons for failure:
1. Driver internal problem, ENOMEM or some such.
2. Device problem (the memory device capability isn't present).

I think I'll return ENODEV for the former and ENXIO for the latter. If that
sounds good to everyone else.

  reply	other threads:[~2020-11-23 19:58 UTC|newest]

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-11  5:43 [RFC PATCH 0/9] CXL 2.0 Support Ben Widawsky
2020-11-11  5:43 ` [RFC PATCH 1/9] cxl/acpi: Add an acpi_cxl module for the CXL interconnect Ben Widawsky
2020-11-11  6:17   ` Randy Dunlap
2020-11-11  7:10   ` Christoph Hellwig
2020-11-11  7:30     ` Verma, Vishal L
2020-11-11  7:34       ` hch
2020-11-11  7:36         ` Verma, Vishal L
2020-11-11 23:03   ` Bjorn Helgaas
2020-11-16 17:59   ` Jonathan Cameron
2020-11-16 18:23     ` Verma, Vishal L
2020-11-17 14:32   ` Rafael J. Wysocki
2020-11-17 21:45     ` Dan Williams
2020-11-18 11:14       ` Rafael J. Wysocki
2020-11-11  5:43 ` [RFC PATCH 2/9] cxl/acpi: add OSC support Ben Widawsky
2020-11-16 17:59   ` Jonathan Cameron
2020-11-16 23:25     ` Dan Williams
2020-11-18 12:25       ` Rafael J. Wysocki
2020-11-18 17:58         ` Dan Williams
2020-11-11  5:43 ` [RFC PATCH 3/9] cxl/mem: Add a driver for the type-3 mailbox Ben Widawsky
2020-11-11  6:17   ` Randy Dunlap
2020-11-11  7:12   ` Christoph Hellwig
2020-11-11 17:17     ` Dan Williams
2020-11-11 18:27       ` Dan Williams
2020-11-11 21:41       ` Randy Dunlap
2020-11-11 22:40         ` Dan Williams
2020-11-16 16:56       ` Christoph Hellwig
2020-11-13 18:17   ` Bjorn Helgaas
2020-11-14  1:08     ` Ben Widawsky
2020-11-15  0:23       ` Dan Williams
2020-11-17 14:49   ` Jonathan Cameron
2020-12-04  7:22     ` Dan Williams
2020-12-04  7:27       ` Dan Williams
2020-12-04 17:39         ` Jonathan Cameron
2020-11-11  5:43 ` [RFC PATCH 4/9] cxl/mem: Map memory device registers Ben Widawsky
2020-11-13 18:17   ` Bjorn Helgaas
2020-11-14  1:12     ` Ben Widawsky
2020-11-16 23:19       ` Dan Williams
2020-11-17  0:23         ` Bjorn Helgaas
2020-11-23 19:20           ` Ben Widawsky
2020-11-23 19:32             ` Dan Williams
2020-11-23 19:58               ` Ben Widawsky [this message]
2020-11-17 15:00   ` Jonathan Cameron
2020-11-11  5:43 ` [RFC PATCH 5/9] cxl/mem: Find device capabilities Ben Widawsky
2020-11-13 18:26   ` Bjorn Helgaas
2020-11-14  1:36     ` Ben Widawsky
2020-11-17 15:15   ` Jonathan Cameron
2020-11-24  0:17     ` Ben Widawsky
2020-11-26  6:05   ` Jon Masters
2020-11-26 18:18     ` Ben Widawsky
2020-12-04  7:35     ` Dan Williams
2020-12-04  7:41   ` Dan Williams
2020-12-07  6:12     ` Ben Widawsky
2020-11-11  5:43 ` [RFC PATCH 6/9] cxl/mem: Initialize the mailbox interface Ben Widawsky
2020-11-17 15:22   ` Jonathan Cameron
2020-11-11  5:43 ` [RFC PATCH 7/9] cxl/mem: Implement polled mode mailbox Ben Widawsky
2020-11-13 23:14   ` Bjorn Helgaas
2020-11-17 15:31   ` Jonathan Cameron
2020-11-17 16:34     ` Ben Widawsky
2020-11-17 18:06       ` Jonathan Cameron
2020-11-17 18:38         ` Dan Williams
2020-11-11  5:43 ` [RFC PATCH 8/9] cxl/mem: Register CXL memX devices Ben Widawsky
2020-11-17 15:56   ` Jonathan Cameron
2020-11-20  2:16     ` Dan Williams
2020-11-20 15:20       ` Jonathan Cameron
2020-11-11  5:43 ` [RFC PATCH 9/9] MAINTAINERS: Add maintainers of the CXL driver Ben Widawsky
2020-11-11 22:06 ` [RFC PATCH 0/9] CXL 2.0 Support Ben Widawsky
2020-11-11 22:43 ` Bjorn Helgaas

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