From: "Matthew R. Ochs" <mrochs@linux.vnet.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>,
"Manoj N . Kumar" <manoj@linux.vnet.ibm.com>,
linux-scsi@vger.kernel.org,
Frederic Barrat <fbarrat@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org,
Uma Krishnan <ukrishn@linux.vnet.ibm.com>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] scsi: cxlflash: Select SCSI_SCAN_ASYNC
Date: Tue, 20 Feb 2018 21:23:01 -0600 [thread overview]
Message-ID: <20180221032301.GA58304@p8tul1-build.aus.stglabs.ibm.com> (raw)
In-Reply-To: <87sh9wrqd8.fsf@concordia.ellerman.id.au>
On Tue, Feb 20, 2018 at 07:56:35PM +1100, Michael Ellerman wrote:
> Vaibhav Jain <vaibhav@linux.vnet.ibm.com> writes:
>
> > The cxlflash driver uses "Asynchronous SCSI scanning" enabled by
> > CONFIG_SCSI_SCAN_ASYNC. Without this enabled the modprobe of cxlflash
> > module gets hung with following backtrace:
> >
> > Call Trace:
> > __switch_to+0x2cc/0x470
> > __schedule+0x288/0xab0
> > schedule+0x40/0xc0
> > schedule_timeout+0x254/0x4f0
> > wait_for_common+0xdc/0x260
> > flush_work+0x140/0x2a0
> > work_on_cpu+0x88/0xb0
> > pci_device_probe+0x1d0/0x220
> > driver_probe_device+0x408/0x5b0
> > __driver_attach+0x16c/0x1a0
> > bus_for_each_dev+0xb8/0x110
> > driver_attach+0x3c/0x60
> > bus_add_driver+0x1d8/0x370
> > driver_register+0x9c/0x180
> > __pci_register_driver+0x74/0xa0
> > init_cxlflash+0x158/0x1cc
> > do_one_initcall+0x68/0x1e0
> > do_init_module+0x90/0x254
> > load_module+0x2f8c/0x3720
> > SyS_finit_module+0xcc/0x140
> > system_call+0x58/0x6c
>
> Why does it "hang"? That's kind of bizarre, I would expect either a
> build or runtime failure if a feature the driver requires is missing.
>
It hangs due to a bug in the driver. I briefly looked at it several
months back before getting distracted with other items. IIRC there
was an issue with the state machine.
> > diff --git a/drivers/scsi/cxlflash/Kconfig b/drivers/scsi/cxlflash/Kconfig
> > index a011c5dbf214..f054c1b0fff3 100644
> > --- a/drivers/scsi/cxlflash/Kconfig
> > +++ b/drivers/scsi/cxlflash/Kconfig
> > @@ -6,6 +6,7 @@ config CXLFLASH
> > tristate "Support for IBM CAPI Flash"
> > depends on PCI && SCSI && CXL && EEH
> > select IRQ_POLL
> > + select SCSI_SCAN_ASYNC
>
> It's user configurable, so it's rude to select it. It can also be
> disabled on the kernel command line, so this seems like a fragile
> solution.
>
I think Vaibhav's intention here was to avoid the hang while the bug
is still present - I believe he has encountered it several times recently.
The proper solution would be to fix the bug.
prev parent reply other threads:[~2018-02-21 3:23 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-19 7:10 Vaibhav Jain
2018-02-20 8:56 ` Michael Ellerman
2018-02-21 3:23 ` Matthew R. Ochs [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=20180221032301.GA58304@p8tul1-build.aus.stglabs.ibm.com \
--to=mrochs@linux.vnet.ibm.com \
--cc=fbarrat@linux.vnet.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-scsi@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=manoj@linux.vnet.ibm.com \
--cc=mpe@ellerman.id.au \
--cc=ukrishn@linux.vnet.ibm.com \
--cc=vaibhav@linux.vnet.ibm.com \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®