Make libata more robust when parsing the multi_count
field 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>
---
Updated to use is_power_of_2() as suggested by Tejun.
Make libata more robust when parsing the multi_count
field 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>
---
Updated to use is_power_of_2() as suggested by Tejun.
--- upstream/drivers/ata/libata-core.c 2009-03-18 11:08:27.000000000 -0400
+++ new/drivers/ata/libata-core.c 2009-03-19 13:21:46.000000000 -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 +2427,15 @@
dev->n_sectors = ata_id_n_sectors(id);
- if (dev->id[59] & 0x100)
- dev->multi_count = dev->id[59] & 0xff;
+ /* get 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 (is_power_of_2(max) && is_power_of_2(cnt))
+ if (cnt <= max)
+ dev->multi_count = cnt;
+ }
if (ata_id_has_lba(id)) {
const char *lba_desc;
--- libata-dev/drivers/ata/libata-core.c.orig 2009-03-18 11:08:27.000000000 -0400
+++ libata-dev/drivers/ata/libata-core.c 2009-03-19 13:26:37.000000000 -0400
@@ -57,6 +57,7 @@
#include <linux/scatterlist.h>
#include <linux/io.h>
#include <linux/async.h>
+#include <linux/log2.h>
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_host.h>
@@ -2389,6 +2390,7 @@
dev->cylinders = 0;
dev->heads = 0;
dev->sectors = 0;
+ dev->multi_count = 0;
/*
* common ATA, ATAPI feature tests
@@ -2426,8 +2428,15 @@
dev->n_sectors = ata_id_n_sectors(id);
- if (dev->id[59] & 0x100)
- dev->multi_count = dev->id[59] & 0xff;
+ /* get 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 (is_power_of_2(max) && is_power_of_2(cnt))
+ if (cnt <= max)
+ dev->multi_count = cnt;
+ }
if (ata_id_has_lba(id)) {
const char *lba_desc;
--
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