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/ahci.c b/drivers/scsi/ahci.c
index da5bd33d982d..8b468a628700 100644
--- a/drivers/scsi/ahci.c
+++ b/drivers/scsi/ahci.c
@@ -289,6 +289,8 @@ static void ahci_host_stop(struct ata_host_set *host_set)
 {
         struct ahci_host_priv *hpriv = host_set->private_data;
         kfree(hpriv);
+
+        ata_host_stop(host_set);
 }
 
 static int ahci_port_start(struct ata_port *ap)