Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> wrote:
> > Has anyone else reported a problem like this? It requires
> > non-coherent DMA, and a lack of a cache invalidate instruction, and
> > one of the drivers that has this problem (it looks like sata_qstor
> > does too, I haven't looked at others), so maybe that doesn't cover
> > any other architectures.
>
> Nobody has, not even PA-RISC which is normally guaranteed to make life
> miserable in the caching area but I agree entirely with your diagnosis
> and that buffer should indeed be marked cache aligned
>
> > I can provide a patch if you're interested.
>
> Please do.
Here it is. I'd appreciate it if someone could sanity check where I'm
freeing the buffer. It works, but I don't know the code well enough
to know if this covers all cases.
I'm counting on kmalloc to return a cache aligned buffer. I found
some reason to think it does, but I don't remember offhand what that
reason was, or if it's configurable per-architecture. The buffer has
to be both physically and virtually contiguous, I was tempted to just
allocate a page and waste some space but we've got 64K pages, so I'm a
bit more sensitive about that.
*** drivers/scsi/libata-core.c 2008-02-13 13:34:32.141489000 -0500
--- drivers/scsi/libata-core.c.orig 2008-02-13 13:29:35.620360000 -0500
***************
*** 5335,5369 ****
}
host = scsi_host_alloc(ent->sht, sizeof(struct ata_port));
if (!host)
return NULL;
host->transportt = &ata_scsi_transport_template;
ap = ata_shost_to_port(host);
- ap->sector_buf = kmalloc(ATA_SECT_SIZE, GFP_KERNEL);
- if (!ap->sector_buf)
- goto err_out;
-
ata_host_init(ap, host, host_set, ent, port_no);
rc = ap->ops->port_start(ap);
if (rc)
goto err_out;
return ap;
err_out:
- if (ap->sector_buf)
- kfree(ap->sector_buf);
scsi_host_put(host);
return NULL;
}
/**
* ata_device_add - Register hardware device with ATA and SCSI layers
* @ent: Probe information describing hardware device to be registered
*
* This function processes the information provided in the probe
* information struct @ent, allocates the necessary ATA and SCSI
--- 5335,5363 ----
***************
*** 5602,5645 ****
* Unregister all objects associated with this host set. Free those
* objects.
*
* LOCKING:
* Inherited from calling layer (may sleep).
*/
void ata_host_set_remove(struct ata_host_set *host_set)
{
unsigned int i;
- u8 *sector_buf;
for (i = 0; i < host_set->n_ports; i++)
ata_port_detach(host_set->ports[i]);
free_irq(host_set->irq, host_set);
for (i = 0; i < host_set->n_ports; i++) {
struct ata_port *ap = host_set->ports[i];
ata_scsi_release(ap->host);
if ((ap->flags & ATA_FLAG_NO_LEGACY) == 0) {
struct ata_ioports *ioaddr = &ap->ioaddr;
if (ioaddr->cmd_addr == 0x1f0)
release_region(0x1f0, 8);
else if (ioaddr->cmd_addr == 0x170)
release_region(0x170, 8);
}
- sector_buf = ap->sector_buf;
scsi_host_put(ap->host);
- kfree(sector_buf);
}
if (host_set->ops->host_stop)
host_set->ops->host_stop(host_set);
kfree(host_set);
}
/**
* ata_scsi_release - SCSI layer callback hook for host unload
--- 5596,5636 ----
-
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