[PATCH] Stability fixes for IPS driver for 4.x

[Scott Long]

David Sze wrote:
> At 11:31 PM 10/04/2005 -0600, Scott Long wrote this to All:
> 
>> Making a driver PAE-ified means either teaching it to do 64-bit
>> scatter-gather (assuming that the peripheral hardware can do this
>> and that it's documented), or teaching the driver to correctly handle
>> EINPROGRESS from bus_dmamap_load() along with using the proper busdma
>> tag limits.  The strategy I took with 6.x/5.x was the second one since
>> I didn't have good IPS docs in front of me and I wanted it follow the
>> APIs correctly.  I did test it with 8GB of memory and it performed
>> correctly under load.  I haven't taken a close enough look at your
>> MFC patch to say for sure if it's correct or not.  I'm not sure if
>> I'll have time to take another look in the next few days, unfortunately.
>> Is there any chance you could test 5.x/6.0 under load with PAE just to
>> validate the assertion that it works correctly there?
> 
> 
> I had a chance to test 5.4-RC1 (i386) today with GENERIC, SMP, PAE, and 
> SMP-PAE kernels (the last one is just PAE with "options SMP").
> 
> To recap, the hardware is an IBM xSeries 346, Dual Xeon 3GHz 
> (non-E64MT), ServeRAID-7K.
> 
> GENERIC and SMP survived "make buildkernel", but PAE and SMP-PAE paniced 
> reproducibly doing the same.  The DDB stack trace doesn't appear to be 
> anywhere near the IPS driver though, so I'm way out of my league.
> 
> 

Darnit, hard to say if this is an existing bug in 5.4 or if it's a 
bug/corruption in ips.  Can you re-run with PAE disabled?  Would you be
willing to put the Giant lock back on top of the driver?  This would
mean modifying the call to bus_intr_config(), adding the D_GIANTNEEDED
flag to the disk structure in disk_create(), and switching the mutex
argument in bus_dma_tag_create() for the sg_dmatag tag.

Scott