libata: Fix use-after-iounmap

Jens Axboe pointed out that the iounmap() call in libata was occurring
too early, and some drivers (ahci, probably others) were using ioremap'd
memory after it had been unmapped.

The patch should address that problem by way of improving the libata
driver API:

* move ->host_stop() call after all ->port_stop() calls have occurred.

* create default helper function ata_host_stop(), and move iounmap()
call there.

* add ->host_stop_prewalk() hook, use it in sata_qstor.c (hi Mark).
sata_qstor appears to require the host-stop-before-port-stop ordering
that existed prior to applying the attached patch.

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/scsi/sata_sx4.c b/drivers/scsi/sata_sx4.c
index 70118650c461..140cea05de3f 100644
--- a/drivers/scsi/sata_sx4.c
+++ b/drivers/scsi/sata_sx4.c
@@ -245,6 +245,8 @@ static void pdc20621_host_stop(struct ata_host_set *host_set)
 
         iounmap(dimm_mmio);
         kfree(hpriv);
+
+        ata_host_stop(host_set);
 }
 
 static int pdc_port_start(struct ata_port *ap)