Re: Call for testers, users with scsi cards

On Tue, Dec 4, 2012 at 2:36 PM, Jeff Roberson <jroberson_at_jroberson.net>wrote:

> http://people.freebsd.org/~**jeff/loadccb.diff<http://people.freebsd.org/~jeff/loadccb.diff>
>
> This patch consolidates all of the functions that map cam control blocks
> for DMA into one central function.  This change is a precursor to adding
> new features to the I/O stack.  It is mostly mechanical.  If you are
> running current on a raid or scsi card, especially if it is a lesser used
> one, I would really like you to apply this patch and report back any
> problems.  If it works you should notice nothing.  If it doesn't work you
> will probably panic immediately on I/O or otherwise no I/O will happen.
>
>
+int
+bus_dmamap_load_ccb(bus_dma_tag_t dmat, bus_dmamap_t map, union ccb *ccb,
+            bus_dmamap_callback_t *callback, void *callback_arg,
+            int flags)
+{
+    struct ccb_ataio *ataio;
+    struct ccb_scsiio *csio;
+    struct ccb_hdr *ccb_h;
+    void *data_ptr;
+    uint32_t dxfer_len;
+    uint16_t sglist_cnt;
+
+    ccb_h = &ccb->ccb_h;
+    if ((ccb_h->flags & CAM_DIR_MASK) == CAM_DIR_NONE) {
+        callback(callback_arg, NULL, 0, 0);
+    }
+

I think you need to return here after invoking the callback.  Otherwise you
drop through and then either invoke the callback again or call
bus_dmamap_load (which will in turn invoke the callback again).

This fix allows the ahci.c change to go back to:

Index: sys/dev/ahci/ahci.c
===================================================================
--- sys/dev/ahci/ahci.c (revision 243900)
+++ sys/dev/ahci/ahci.c (working copy)
_at__at_ -1667,23 +1667,9 _at__at_
            (ccb->ataio.cmd.flags & (CAM_ATAIO_CONTROL |
CAM_ATAIO_NEEDRESULT)))
                ch->aslots |= (1 << slot->slot);
        slot->dma.nsegs = 0;
-       /* If request moves data, setup and load SG list */
-       if ((ccb->ccb_h.flags & CAM_DIR_MASK) != CAM_DIR_NONE) {
-               void *buf;
-               bus_size_t size;
-
-               slot->state = AHCI_SLOT_LOADING;
-               if (ccb->ccb_h.func_code == XPT_ATA_IO) {
-                       buf = ccb->ataio.data_ptr;
-                       size = ccb->ataio.dxfer_len;
-               } else {
-                       buf = ccb->csio.data_ptr;
-                       size = ccb->csio.dxfer_len;
-               }
-               bus_dmamap_load(ch->dma.data_tag, slot->dma.data_map,
-                   buf, size, ahci_dmasetprd, slot, 0);
-       } else
-               ahci_execute_transaction(slot);
+       slot->state = AHCI_SLOT_LOADING;
+       bus_dmamap_load_ccb(ch->dma.data_tag, slot->dma.data_map, ccb,
+           ahci_dmasetprd, slot, 0);
 }

 /* Locked by busdma engine. */

This is almost what you head earlier, but adding back setting of the slot's
state to AHCI_SLOT_LOADING, to cover the case where the load is deferred.
It seems OK to do this even in case where no load is actually happening
(i.e. CAM_DIR_NONE).

-Jim