Re: [PATCH 1/3] pci: VPD access timeout increase

Matthew Wilcox wrote:
On Wed, Sep 03, 2008 at 03:57:13PM -0700, Stephen Hemminger wrote:
Accessing the VPD area can take a long time. There are comments in the
SysKonnect vendor driver that it can take up to 25ms. The existing vpd
access code fails consistently on my hardware.

Wow, that's slow. If you were to try to read all 32k, it'd take more
than three minutes! (I presume it doesn't actually have as much as 32k).

Change the access routines to:
* use a mutex rather than spinning with IRQ's disabled and lock held
* have a longer timeout
* call schedule while spinning to provide some responsivness

I agree with your approach, but have one minor comment:

- spin_lock_irq(&vpd->lock);
+ mutex_lock(&vpd->lock);

This should be:

+ if (mutex_lock_interruptible(&vpd->lock))
+ return -EINTR;
[...]

This is fine for the sysfs case, but not if this is called during device
probe - we don't want signals to modprobe to break device initialisation,
do we?

Ben.

--
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.
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