From: Tejun Heo <tj@kernel.org>
To: Alexander Gordeev <agordeev@redhat.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Michael Ellerman <michael@ellerman.id.au>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Ben Hutchings <bhutchings@solarflare.com>,
David Laight <David.Laight@aculab.com>,
Mark Lord <kernel@start.ca>, "H. Peter Anvin" <hpa@zytor.com>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>
Subject: Re: [PATCH v4 9/9] PCI/MSI: Introduce pci_auto_enable_msi*() family helpers
Date: Thu, 19 Dec 2013 08:47:19 -0500 [thread overview]
Message-ID: <20131219134719.GA16994@htj.dyndns.org> (raw)
In-Reply-To: <20131219134244.GA32238@dhcp-26-207.brq.redhat.com>
Hello,
On Thu, Dec 19, 2013 at 02:42:45PM +0100, Alexander Gordeev wrote:
> I have troubles with this fallback logic. On each failed step we get an
> error and we do not know if this is indeed an error or an indication of
> insufficient MSI resources. Even -ENOSPC would not tell much, since it
> could be thrown from a lower level.
Well, it's not hard to define what -ENOSPC should mean.
> By contrast, with the tri-state return value we can distinguish and bail
> out on errors right away.
I kinda like that the available options are listed explicitly on the
caller side (even if it ends up being a loop). It decreases the
chance of the caller going "oh I didn't expect _that_" and generaly
makes things easier to follow.
> So the above is bit ungraceful for me. Combined with a possible waste in
> logs (if we're hitting the same error) it is quite enough for me to keep
> current the interfaces, at least for a time being.
FWIW, I like Bjorn's suggestion. Given that this is mostly corner
case thing, it isn't as important as the common ones but we might as
well while we're at it.
Thanks a lot for your work in the area! :)
--
tejun
next prev parent reply other threads:[~2013-12-19 13:47 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-16 8:34 [PATCH v4 0/9] PCI/MSI: Introduce pci_auto_enable_msi*() family helpers Alexander Gordeev
2013-12-16 8:34 ` [PATCH v4 1/9] PCI/MSI/s390: Fix single MSI only check Alexander Gordeev
2013-12-16 8:34 ` [PATCH v4 2/9] PCI/MSI/s390: Remove superfluous check of MSI type Alexander Gordeev
2013-12-16 8:34 ` [PATCH v4 3/9] PCI/MSI: Fix return value when populate_msi_sysfs() failed Alexander Gordeev
2013-12-16 8:34 ` [PATCH v4 4/9] PCI/MSI: Return -ENOSYS for unimplemented interfaces, not -1 Alexander Gordeev
2013-12-16 8:34 ` [PATCH v4 5/9] PCI/MSI: Make pci_enable_msi/msix() 'nvec' argument type as int Alexander Gordeev
2013-12-16 8:34 ` [PATCH v4 6/9] PCI/MSI: Factor out pci_get_msi_vec_count() interface Alexander Gordeev
2013-12-18 0:33 ` Bjorn Helgaas
2013-12-16 8:35 ` [PATCH v4 7/9] PCI/MSI: Get rid of pci_enable_msi_block_auto() interface Alexander Gordeev
2013-12-16 8:35 ` [PATCH v4 8/9] PCI/MSI: Introduce pci_get_msix_vec_count() interface Alexander Gordeev
2013-12-16 8:35 ` [PATCH v4 9/9] PCI/MSI: Introduce pci_auto_enable_msi*() family helpers Alexander Gordeev
2013-12-18 0:30 ` Bjorn Helgaas
2013-12-18 13:23 ` Alexander Gordeev
2013-12-18 18:58 ` Bjorn Helgaas
2013-12-19 13:42 ` Alexander Gordeev
2013-12-19 13:47 ` Tejun Heo [this message]
2013-12-19 21:37 ` Bjorn Helgaas
2013-12-20 9:04 ` Alexander Gordeev
2013-12-20 13:28 ` Tejun Heo
2013-12-20 10:28 ` Alexander Gordeev
2013-12-23 14:44 ` Alexander Gordeev
2013-12-23 17:19 ` Bjorn Helgaas
2013-12-19 22:30 ` [PATCH v4 0/9] " Bjorn Helgaas
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