From: Finn Thain <fthain@telegraphics.com.au>
To: Ondrej Zary <linux@rainbow-software.org>
Cc: Christoph Hellwig <hch@infradead.org>,
linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/6] g_NCR5380: Test the IRQ before accepting it
Date: Thu, 3 Nov 2016 13:17:04 +1100 (AEDT) [thread overview]
Message-ID: <alpine.LNX.2.00.1611031151350.14245@nippy.intranet> (raw)
In-Reply-To: <201611022016.00556.linux@rainbow-software.org>
On Wed, 2 Nov 2016, Ondrej Zary wrote:
> On Wednesday 02 November 2016 08:45:26 Finn Thain wrote:
> > On Mon, 31 Oct 2016, Ondrej Zary wrote:
> > > Trigger an IRQ first with a test IRQ handler to find out if it
> > > really works. Disable the IRQ if not.
> > >
> > > This prevents hang when incorrect IRQ was specified by user.
> >
> > Once again, how does it cause a hang?
>
> Kernel scans the bus, finds a HDD, then attempts to read MBR. modprobe
> process is stuck but the system is still running. Then the transfer
> probably times out and everything locks up hard, even fbcon cursor stops
> blinking. I guess that kernel is trying to abort or reset.
I don't think this issue relates to the patch, because the chip irq is not
needed for exception handling.
A backtrace from the soft lockup detector should help explain this.
> BTW. rescan-scsi-bus also causes hang, anytime, even without IRQ.
I would try "scsi_logging_level -s -a 7" to find out what is going on
during the bus scan (for modprobe or rescan-scsi-bus).
The polling loops in generic_NCR5380_pread/pwrite can cause a lockup
because they lack timeouts. Better to call NCR5380_poll_politely, as in
macscsi_pread/pwrite.
--
next prev parent reply other threads:[~2016-11-03 2:16 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-31 20:18 [PATCH 0/6] (g_)NCR5380: Improve IRQ probing and some fixes Ondrej Zary
2016-10-31 20:18 ` [PATCH 1/6] NCR5380: Use probe_irq_*() for IRQ probing Ondrej Zary
2016-11-02 7:45 ` Finn Thain
2016-11-02 8:00 ` Ondrej Zary
2016-11-03 2:16 ` Finn Thain
2016-10-31 20:18 ` [PATCH 2/6] g_NCR5380: Test the IRQ before accepting it Ondrej Zary
2016-11-02 7:45 ` Finn Thain
2016-11-02 19:16 ` Ondrej Zary
2016-11-03 2:17 ` Finn Thain [this message]
2016-10-31 20:18 ` [PATCH 3/6] g_NCR5380: Check for chip presence before calling NCR5380_init() Ondrej Zary
2016-11-02 7:46 ` Finn Thain
2016-10-31 20:18 ` [PATCH 4/6] g_NCR5380: Add IRQ auto-configuration for HP C2502 Ondrej Zary
2016-11-02 7:46 ` Finn Thain
2016-11-02 8:29 ` Ondrej Zary
2016-11-03 2:17 ` Finn Thain
2016-11-03 8:00 ` Ondrej Zary
2016-11-04 3:00 ` Finn Thain
2016-10-31 20:18 ` [PATCH 5/6] g_NCR5380: Autoprobe IRQ by default Ondrej Zary
2016-11-02 7:47 ` Finn Thain
2016-12-03 0:39 ` Finn Thain
2016-10-31 20:18 ` [PATCH 6/6] g_NCR5380: Fix release region in error handling Ondrej Zary
2016-11-02 7:49 ` Finn Thain
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