Attempting to unload a serial ATA driver module gave me a kernel memory fault. I think this problem occurs in all configurations, but I should mention that my configuration may be slightly unusual in that I configured my BIOS not to do IDE emulation with SATA disks, and I don't actually have any disks plugged in.
The problem was that ata_pci_remove_one would call scsi_host_put(ap->host), which would free the memory used to hold host_set->ports, but host_set->ports was used later in ata_pci_remove_one.
So, the following patch reorders some of the steps in ata_pci_remove_one and seems to eliminate the problem, at least to the extent that I can unload and reload the module, although I do not have a SATA disk handy for testing (I'm expecting one to arrive later today).
The patch actually makes the code four lines shorter, although two of those lines come from putting an assignement and variable declaration in the same line. Since the patch is a little hard to read, here is a description of the edit steps.
1. Moved pci_release_regions() to toward the end of the routine to facilitate merging the loops before and after it. Also, I think that calls that are good candidates for consolidating into the bus-level code in the future (instead of individual drivers) are best put at the beginning or end of the driver routines so that it is clearer if there would be problems doing such consolidation.
2. Moved the cacluation of ioaddr into the only if-branch that uses it.
3. Moved the call to scsi_host_put to after the code that checks ATA_FLAG_NO_LEGACY.
Applied to libata-dev, but #3 looks wrong: you always release the kernel subsystem before releasing the hardware resources.
I won't push it upstream until I ponder this some more (and/or an increment patch for this issue appears).
Jeff
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