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SubjectRe: [PATCH next] ide: fix PowerMac bootup oops
Hi Bart,

On Mon, 8 Jun 2009, Bartlomiej Zolnierkiewicz wrote:
>
> After auditing some other host drivers I see that drive->id can be used
> also directly in ->set_pio_mode methods..
>
> Could you please instead try moving ->id allocation from probe_for_drive()
> to ide_port_alloc_devices() (this would fix all such issues for good) and
> verify that it also fixes the oops?

Okay, that makes sense: here's a patch which fixes the oops that way;
but it didn't work first time - see save_id! I'm not entirely happy
with the memsetting, as I comment in the patch, but I don't really
know what reuse these get: please check the decisions I made,
you may well want to change it around a bit.


[PATCH next] ide: fix PowerMac bootup oops

PowerMac bootup with CONFIG_IDE=y oopses in ide_pio_cycle_time():
because "ide: try to use PIO Mode 0 during probe if possible" causes
pmac_ide_set_pio_mode() to be called before drive->id has been set.

Bart points out other places which now need drive->id set earlier,
so follow his advice to allocate it in ide_port_alloc_devices()
(using kzalloc_node, without error message, as when allocating drive).

But memset id in probe_for_drive() when it might be being reused -
or would it be better to memset it wherever it used to be kfreed?

Fixed in passing: ide_host_alloc() was missing ide_port_free_devices()
from an error path.

Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
---

drivers/ide/ide-probe.c | 47 ++++++++++++++++----------------------
1 file changed, 21 insertions(+), 26 deletions(-)

--- lnext/drivers/ide/ide-probe.c 2009-06-03 11:45:13.000000000 +0100
+++ linux/drivers/ide/ide-probe.c 2009-06-09 12:03:55.000000000 +0100
@@ -465,23 +465,9 @@ static u8 probe_for_drive(ide_drive_t *d
int rc;
u8 cmd;

- /*
- * In order to keep things simple we have an id
- * block for all drives at all times. If the device
- * is pre ATA or refuses ATA/ATAPI identify we
- * will add faked data to this.
- *
- * Also note that 0 everywhere means "can't do X"
- */
-
drive->dev_flags &= ~IDE_DFLAG_ID_READ;

- drive->id = kzalloc(SECTOR_SIZE, GFP_KERNEL);
- if (drive->id == NULL) {
- printk(KERN_ERR "ide: out of memory for id data.\n");
- return 0;
- }
-
+ memset(drive->id, 0, SECTOR_SIZE);
m = (char *)&drive->id[ATA_ID_PROD];
strcpy(m, "UNKNOWN");

@@ -497,7 +483,7 @@ static u8 probe_for_drive(ide_drive_t *d
}

if ((drive->dev_flags & IDE_DFLAG_PRESENT) == 0)
- goto out_free;
+ return 0;

/* identification failed? */
if ((drive->dev_flags & IDE_DFLAG_ID_READ) == 0) {
@@ -521,7 +507,7 @@ static u8 probe_for_drive(ide_drive_t *d
}

if ((drive->dev_flags & IDE_DFLAG_PRESENT) == 0)
- goto out_free;
+ return 0;

/* The drive wasn't being helpful. Add generic info only */
if ((drive->dev_flags & IDE_DFLAG_ID_READ) == 0) {
@@ -535,9 +521,6 @@ static u8 probe_for_drive(ide_drive_t *d
}

return 1;
-out_free:
- kfree(drive->id);
- return 0;
}

static void hwif_release_dev(struct device *dev)
@@ -817,8 +800,6 @@ static int ide_port_setup_devices(ide_hw
if (ide_init_queue(drive)) {
printk(KERN_ERR "ide: failed to init %s\n",
drive->name);
- kfree(drive->id);
- drive->id = NULL;
drive->dev_flags &= ~IDE_DFLAG_PRESENT;
continue;
}
@@ -947,9 +928,6 @@ static void drive_release_dev (struct de
blk_cleanup_queue(drive->queue);
drive->queue = NULL;

- kfree(drive->id);
- drive->id = NULL;
-
drive->dev_flags &= ~IDE_DFLAG_PRESENT;

complete(&drive->gendev_rel_comp);
@@ -1132,8 +1110,10 @@ static void ide_port_init_devices_data(i

ide_port_for_each_dev(i, drive, hwif) {
u8 j = (hwif->index * MAX_DRIVES) + i;
+ u16 *saved_id = drive->id;

memset(drive, 0, sizeof(*drive));
+ drive->id = saved_id;

drive->media = ide_disk;
drive->select = (i << 4) | ATA_DEVICE_OBS;
@@ -1240,8 +1220,10 @@ static void ide_port_free_devices(ide_hw
ide_drive_t *drive;
int i;

- ide_port_for_each_dev(i, drive, hwif)
+ ide_port_for_each_dev(i, drive, hwif) {
+ kfree(drive->id);
kfree(drive);
+ }
}

static int ide_port_alloc_devices(ide_hwif_t *hwif, int node)
@@ -1255,6 +1237,18 @@ static int ide_port_alloc_devices(ide_hw
if (drive == NULL)
goto out_nomem;

+ /*
+ * In order to keep things simple we have an id
+ * block for all drives at all times. If the device
+ * is pre ATA or refuses ATA/ATAPI identify we
+ * will add faked data to this.
+ *
+ * Also note that 0 everywhere means "can't do X"
+ */
+ drive->id = kzalloc_node(SECTOR_SIZE, GFP_KERNEL, node);
+ if (drive->id == NULL)
+ goto out_nomem;
+
hwif->devices[i] = drive;
}
return 0;
@@ -1296,6 +1290,7 @@ struct ide_host *ide_host_alloc(const st
if (idx < 0) {
printk(KERN_ERR "%s: no free slot for interface\n",
d ? d->name : "ide");
+ ide_port_free_devices(hwif);
kfree(hwif);
continue;
}

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