Re: Help with SATA driver/libata/SCSI subsystem

[Robert Hancock]

C Z wrote:
> I am attempting to write a SATA driver under libata for a custom core on a Microblaze Xilinx FPGA. I can not get ata_device_add() in drivers/ata/libata-core.c to return successfully.
>
> I have tracked the immediate problem to the function scsi_eh_flush_done_q() in drivers/scsi/scsi_error.c. The problem is this function calls "list_for_each_entry_safe(scmd, next, done_q, eh_entry)". Unfortunately, this returns the result scmd = 0xFFFFFFF0. This very strange address is the result of containerof() being called on a NULL pointer. The NULL pointer is the done_q list head. This is clearly wrong.
>
> I have 2 questions. First, why is libata invoking the error handler after a probe in ata_device_add? This seems very counter intuitive to me. It isn't at all clear why libata needs to do this. Can someone explain the rationale behind this function?

To add to what Jeff said, the error handler thread is used for a lot 
more than just handling errors in libata, including for device probing..
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