From: Lukas Wunner <firstname.lastname@example.org> To: Bjorn Helgaas <email@example.com> Cc: Paul Menzel <firstname.lastname@example.org>, Bjorn Helgaas <email@example.com>, firstname.lastname@example.org, email@example.com, Sinan Kaya <firstname.lastname@example.org> Subject: Re: pciehp 0000:00:1c.0:pcie004: Timeout on hotplug command 0x1038 (issued 65284 msec ago) Date: Wed, 9 May 2018 15:16:00 +0200 [thread overview] Message-ID: <20180509131600.GA3712@wunner.de> (raw) In-Reply-To: <20180509125752.GA234395@bhelgaas-glaptop.roam.corp.google.com> On Wed, May 09, 2018 at 07:57:52AM -0500, Bjorn Helgaas wrote: > On Wed, May 09, 2018 at 01:41:24PM +0200, Lukas Wunner wrote: > > On Fri, Apr 27, 2018 at 02:22:07PM -0500, Bjorn Helgaas wrote: > > > Sinan mooted the idea of using a "no-wait" path of sending the "don't > > > generate hotplug interrupts" command. I think we should work on this > > > idea a little more. If we're shutting down the whole system, I can't > > > believe there's much value in *anything* we do in the pciehp_remove() > > > path. > > > > > > Maybe we should just get rid of pciehp_remove() (and probably > > > pcie_port_remove_service() and the other service driver remove methods) > > > completely. That dates from when the service drivers could be modules that > > > could be potentially unloaded, but unloading them hasn't been possible for > > > years. > > > > Every Thunderbolt device contains a PCIe switch with at least one > > (downstream) hotplug port, so pciehp_remove() is executed on unplug > > of a Thunderbolt device and the assumption that it's unnecessary > > simply because it's builtin isn't correct. > > I agree that simply being builtin isn't a sufficient argument for getting > rid of pciehp_remove(). > > But if we do need pciehp_remove(), we should be able to make a rational > case for why that is. If we're about to turn off the power, it's not > obvious why we would need to deallocate memory, remove sysfs stuff, etc. > If we need to configure the hardware to make it easier for a kexec'd > kernel, that's a possible argument but we should make it explicit. With Thunderbolt, up to 6 devices may be daisy-chained. This means that a hotplug port may have further hotplug ports as (grand-)children. If power is turned off manually via sysfs for a hotplug port, all children (including hotplug ports) are removed by pciehp even though they physically remain attached to the machine. If such removed-in-software-but-physically- still-present devices send an interrupt, and interrupts were not orderly disabled on ->remove, they will be considered spurious interrupts by genirq code. In particular, level-triggered INTx interrupts will immediately lead to an unpleasant user-visible splat and the interrupt will be switched to polling. So there's no way around orderly disabling interrupts in the ->remove path. I agree that ->shutdown is a different story in principle and that disabling devices seems superfluous and counter-intuitive. I imagine kexec might not be the only reason, but also devices passed through to VMs. (What happens if a VM hands a device back to the host in an unclean state on shutdown?) Thanks, Lukas
prev parent reply other threads:[~2018-05-09 13:16 UTC|newest] Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-04-26 10:17 Paul Menzel 2018-04-27 19:22 ` Bjorn Helgaas 2018-04-27 19:34 ` Sinan Kaya 2018-04-27 21:12 ` Bjorn Helgaas 2018-04-28 0:56 ` Dave Young 2018-04-28 1:18 ` Dave Young 2018-04-28 13:03 ` okaya 2018-04-30 20:48 ` Sinan Kaya 2018-04-30 21:17 ` Bjorn Helgaas 2018-04-30 21:27 ` Sinan Kaya 2018-04-30 21:38 ` Lukas Wunner 2018-05-01 12:38 ` Sinan Kaya 2018-05-01 12:59 ` Marc Zyngier 2018-05-01 13:25 ` Bjorn Helgaas 2018-05-01 16:31 ` Marc Zyngier 2018-05-01 22:32 ` Eric W. Biederman 2018-05-03 8:49 ` Paul Menzel 2018-05-04 2:45 ` Bjorn Helgaas 2018-05-04 6:37 ` okaya 2018-05-04 13:33 ` Bjorn Helgaas 2018-05-04 14:24 ` okaya 2018-05-06 9:35 ` Paul Menzel 2018-05-07 21:33 ` Bjorn Helgaas 2018-05-08 6:59 ` Paul Menzel 2018-05-08 12:34 ` Bjorn Helgaas 2018-05-08 13:22 ` Paul Menzel 2018-05-09 11:41 ` Lukas Wunner 2018-05-09 12:57 ` Bjorn Helgaas 2018-05-09 13:16 ` Lukas Wunner [this message]
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20180509131600.GA3712@wunner.de \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --firstname.lastname@example.org \ --email@example.com \ --subject='Re: pciehp 0000:00:1c.0:pcie004: Timeout on hotplug command 0x1038 (issued 65284 msec ago)' \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).