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libata: clear dev->ering in smarter way

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dev->ering used to be cleared together with the rest of ata_device in
ata_dev_init() which is called whenever a probing event occurs.
dev->ering is about to be used to track probing failures so it needs
to remain persistent over multiple porbing events.  This patch
achieves this by doing the following.

* Instead of CLEAR_OFFSET, define CLEAR_BEGIN and CLEAR_END and only
  clear between BEGIN and END.  ering is moved after END.  The split
  of persistent area is to allow hotter items remain at the head.

* ering is explicitly cleared on ata_dev_disable() and when device
  attach succeeds.  So, ering is persistent throug a device's life
  time (unless explicitly cleared of course) and also through periods
  inbetween disablement of an attached device and successful detection
  of the next one.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
This commit is contained in:
Tejun Heo 2009-01-29 20:31:32 +09:00 • committed by Jeff Garzik
parent 9913ff8abf
commit 99cf610aa4
3 changed files with 19 additions and 10 deletions
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18
include/linux/libata.h
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@ -580,7 +580,7 @@ struct ata_device {
acpi_handle acpi_handle;
union acpi_object *gtf_cache;
#endif
/* n_sector is used as CLEAR_OFFSET, read comment above CLEAR_OFFSET */
/* n_sector is CLEAR_BEGIN, read comment above CLEAR_BEGIN */
u64 n_sectors; /* size of device, if ATA */
unsigned int class; /* ATA_DEV_xxx */
unsigned long unpark_deadline;
@ -605,20 +605,22 @@ struct ata_device {
u16 heads; /* Number of heads */
u16 sectors; /* Number of sectors per track */
/* error history */
int spdn_cnt;
struct ata_ering ering;
union {
u16 id[ATA_ID_WORDS]; /* IDENTIFY xxx DEVICE data */
u32 gscr[SATA_PMP_GSCR_DWORDS]; /* PMP GSCR block */
};
/* error history */
int spdn_cnt;
/* ering is CLEAR_END, read comment above CLEAR_END */
struct ata_ering ering;
};
/* Offset into struct ata_device. Fields above it are maintained
* acress device init. Fields below are zeroed.
/* Fields between ATA_DEVICE_CLEAR_BEGIN and ATA_DEVICE_CLEAR_END are
* cleared to zero on ata_dev_init().
*/
#define ATA_DEVICE_CLEAR_OFFSET offsetof(struct ata_device, n_sectors)
#define ATA_DEVICE_CLEAR_BEGIN offsetof(struct ata_device, n_sectors)
#define ATA_DEVICE_CLEAR_END offsetof(struct ata_device, ering)
struct ata_eh_info {
struct ata_device *dev; /* offending device */