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[PATCH] libata-eh-fw: use special reserved tag and qc for internal commands

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New EH may issue internal commands to recover from error while failed
qc's are still hanging around.  To allow such usage, reserve tag
ATA_MAX_QUEUE-1 for internal command.  This also makes it easy to tell
whether a qc is for internal command or not.  ata_tag_internal() test
implements this test.

To avoid breaking existing drivers, ata_exec_internal() uses
ATA_TAG_INTERNAL only for drivers which implement ->error_handler.
For drivers using old EH, tag 0 is used.  Note that this makes
ata_tag_internal() test valid only when ->error_handler is
implemented.  This is okay as drivers on old EH should not and does
not have any reason to use ata_tag_internal().

Signed-off-by: Tejun Heo <htejun@gmail.com>
This commit is contained in:
Tejun Heo 2006-05-15 20:58:02 +09:00
parent dc2b351586
commit 2ab7db1ff1
2 changed files with 37 additions and 4 deletions
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32
drivers/scsi/libata-core.c
View file

@ -980,15 +980,39 @@ unsigned ata_exec_internal(struct ata_device *dev,
struct ata_port *ap = dev->ap;
u8 command = tf->command;
struct ata_queued_cmd *qc;
unsigned int tag, preempted_tag;
DECLARE_COMPLETION(wait);
unsigned long flags;
unsigned int err_mask;
spin_lock_irqsave(&ap->host_set->lock, flags);
qc = ata_qc_new_init(dev);
BUG_ON(qc == NULL);
/* initialize internal qc */
/* XXX: Tag 0 is used for drivers with legacy EH as some
* drivers choke if any other tag is given. This breaks
* ata_tag_internal() test for those drivers. Don't use new
* EH stuff without converting to it.
*/
if (ap->ops->error_handler)
tag = ATA_TAG_INTERNAL;
else
tag = 0;
if (test_and_set_bit(tag, &ap->qactive))
BUG();
qc = ata_qc_from_tag(ap, tag);
qc->tag = tag;
qc->scsicmd = NULL;
qc->ap = ap;
qc->dev = dev;
ata_qc_reinit(qc);
preempted_tag = ap->active_tag;
ap->active_tag = ATA_TAG_POISON;
/* prepare & issue qc */
qc->tf = *tf;
if (cdb)
memcpy(qc->cdb, cdb, ATAPI_CDB_LEN);
@ -1035,6 +1059,7 @@ unsigned ata_exec_internal(struct ata_device *dev,
err_mask = qc->err_mask;
ata_qc_free(qc);
ap->active_tag = preempted_tag;
/* XXX - Some LLDDs (sata_mv) disable port on command failure.
* Until those drivers are fixed, we detect the condition
@ -4014,7 +4039,8 @@ static struct ata_queued_cmd *ata_qc_new(struct ata_port *ap)
struct ata_queued_cmd *qc = NULL;
unsigned int i;
for (i = 0; i < ATA_MAX_QUEUE; i++)
/* the last tag is reserved for internal command. */
for (i = 0; i < ATA_MAX_QUEUE - 1; i++)
if (!test_and_set_bit(i, &ap->qactive)) {
qc = ata_qc_from_tag(ap, i);
break;

9
include/linux/libata.h
View file

@ -108,7 +108,9 @@ enum {
LIBATA_MAX_PRD = ATA_MAX_PRD / 2,
ATA_MAX_PORTS = 8,
ATA_DEF_QUEUE = 1,
ATA_MAX_QUEUE = 1,
/* tag ATA_MAX_QUEUE - 1 is reserved for internal commands */
ATA_MAX_QUEUE = 2,
ATA_TAG_INTERNAL = ATA_MAX_QUEUE - 1,
ATA_MAX_SECTORS = 200, /* FIXME */
ATA_MAX_BUS = 2,
ATA_DEF_BUSY_WAIT = 10000,
@ -717,6 +719,11 @@ static inline unsigned int ata_tag_valid(unsigned int tag)
return (tag < ATA_MAX_QUEUE) ? 1 : 0;
}
static inline unsigned int ata_tag_internal(unsigned int tag)
{
return tag == ATA_MAX_QUEUE - 1;
}
static inline unsigned int ata_class_enabled(unsigned int class)
{
return class == ATA_DEV_ATA || class == ATA_DEV_ATAPI;