Mark Lord wrote:
Make libata more robust when parsing the multi_count
fields from a drive's identify data. This prevents us from
attempting to use dubious multi_count values ad infinitum.
Reset dev->multi_count to zero and reprobe it each time
through this routine, as it can change on device reset.
Also ensure that the reported "maximum" value is valid
and is a power of two, and that the reported "count" value
is valid and also a power of two. And that the "count"
value is not greater than the "maximum" value.
Signed-off-by: Mark Lord <mlord@xxxxxxxxx>
--- upstream/drivers/ata/libata-core.c.orig 2009-03-18
11:08:27.000000000 -0400
+++ new/drivers/ata/libata-core.c 2009-03-18 12:09:31.000000000 -0400
@@ -2389,6 +2389,7 @@
dev->cylinders = 0;
dev->heads = 0;
dev->sectors = 0;
+ dev->multi_count = 0;
/*
* common ATA, ATAPI feature tests
@@ -2426,8 +2427,16 @@
dev->n_sectors = ata_id_n_sectors(id);
- if (dev->id[59] & 0x100)
- dev->multi_count = dev->id[59] & 0xff;
+ /* get/validate current R/W Multiple count setting */
+ if ((dev->id[47] >> 8) == 0x80 && (dev->id[59] & 0x100)) {
+ unsigned int max = dev->id[47] & 0xff;
+ unsigned int cnt = dev->id[59] & 0xff;
+ /* only recognize/allow powers of two here */
+ if (cnt && cnt <= max && (max & (max - 1)) == 0) {
+ if ((cnt & (cnt - 1)) == 0)
+ dev->multi_count = cnt;
+ }
+ }
if (ata_id_has_lba(id)) {
const char *lba_desc;
..
Note that this patch still allows (dev->multi_count == 1),
as before, though this may or may not be a good idea.
Right now, we should probably just treat "1" the same as "0",
and not use R/W multi commands with that setting.
But at some point, libata will gain HDIO_SET_MULTCOUNT support
and/or a sysfs attr for it. At which point there's no reason
to force policy on a multi_count of 1.
Opinions?
We can change that behaviour with a second, follow-up, patch if need be.
Cheers
--
To unsubscribe from this list: send the line "unsubscribe linux-ide" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
