isci: preallocate remote devices

Until we synchronize against device removal this limits the damage of
use after free bugs to the driver's own objects.  Unless we implement
reference counting we need to ensure at least a subset of a remote
device is valid at all times.  We follow the lead of other libsas
drivers that also preallocate devices.

This also enforces maximum remote device accounting at the lldd layer,
but the core may still run out of RNC's before we hit this limit.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 12 insertions, 5 deletions

diff --git a/drivers/scsi/isci/host.h b/drivers/scsi/isci/host.h
index 6a6304c06976..3c69f1ffb1c3 100644
--- a/drivers/scsi/isci/host.h
+++ b/drivers/scsi/isci/host.h
@@ -61,6 +61,7 @@
 /*#include "task.h"*/
 #include "timers.h"
 #include "remote_device.h"
+#include "scic_remote_device.h"
 
 #define DRV_NAME "isci"
 #define SCI_PCI_BAR_COUNT 2
@@ -117,8 +118,18 @@ struct isci_host {
         struct list_head requests_to_complete;
         struct list_head requests_to_abort;
         spinlock_t scic_lock;
+
+        /* careful only access this via idev_by_id */
+        struct isci_remote_device devices[0];
 };
 
+static inline struct isci_remote_device *idev_by_id(struct isci_host *ihost, int i)
+{
+        void *p = ihost->devices;
+
+        return p + i * (sizeof(struct isci_remote_device) +
+                        scic_remote_device_get_object_size());
+}
 
 /**
  * struct isci_pci_info - This class represents the pci function containing the
@@ -219,11 +230,7 @@ static inline void wait_for_device_start(struct isci_host *ihost, struct isci_re
 
 static inline void wait_for_device_stop(struct isci_host *ihost, struct isci_remote_device *idev)
 {
-        /* todo switch to:
-         * wait_event(ihost->eventq, !test_bit(IDEV_STOP_PENDING, &idev->flags));
-         * once devices are statically allocated
-         */
-        wait_for_completion(idev->cmp);
+        wait_event(ihost->eventq, !test_bit(IDEV_STOP_PENDING, &idev->flags));
 }
 
 /**