Lifetimes of some fields span over device plugging/unplugging. This
patch moves such persistent fields to the top of ata_device and
separate them with ATA_DEVICE_CLEAR_OFFSET. Fields above the offset
are initialized once during host initializatino while all other fields
are cleared before hotplugging. Currently ->ap, devno and part of
flags are persistent.
Note that flags is partially cleared while holding host_set lock.
This is to synchronize with later warm plug implementation which will
record hotplug request in dev->flags.
Signed-off-by: Tejun Heo <htejun@xxxxxxxxx>
---
drivers/scsi/libata-core.c | 14 ++++++++++++--
include/linux/libata.h | 11 +++++++++--
2 files changed, 21 insertions(+), 4 deletions(-)
a615dbf0ff4deac11925b7be6916caed19a66f3e
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 84afb59..fc9989d 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -5153,9 +5153,18 @@ static void ata_host_remove(struct ata_p
void ata_dev_init(struct ata_device *dev)
{
struct ata_port *ap = dev->ap;
+ unsigned long flags;
+
+ /* High bits of dev->flags are used to record warm plug
+ * requests which occur asynchronously. Synchronize using
+ * host_set lock.
+ */
+ spin_lock_irqsave(&ap->host_set->lock, flags);
+ dev->flags &= ~ATA_DFLAG_INIT_MASK;
+ spin_unlock_irqrestore(&ap->host_set->lock, flags);
- memset((void *)dev, 0, sizeof(*dev));
- dev->devno = dev - ap->device;
+ memset((void *)dev + ATA_DEVICE_CLEAR_OFFSET, 0,
+ sizeof(*dev) - ATA_DEVICE_CLEAR_OFFSET);
dev->pio_mask = UINT_MAX;
dev->mwdma_mask = UINT_MAX;
dev->udma_mask = UINT_MAX;
@@ -5217,6 +5226,7 @@ static void ata_host_init(struct ata_por
for (i = 0; i < ATA_MAX_DEVICES; i++) {
struct ata_device *dev = &ap->device[i];
dev->ap = ap;
+ dev->devno = i;
ata_dev_init(dev);
}
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 4f67c43..20c6aa1 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -130,6 +130,7 @@ enum {
ATA_DFLAG_CFG_MASK = (1 << 8) - 1,
ATA_DFLAG_PIO = (1 << 8), /* device currently in PIO mode */
+ ATA_DFLAG_INIT_MASK = (1 << 16) - 1,
ATA_DFLAG_DETACH = (1 << 16),
ATA_DFLAG_DETACHED = (1 << 17),
@@ -409,10 +410,11 @@ struct ata_ering {
struct ata_device {
struct ata_port *ap;
- u64 n_sectors; /* size of device, if ATA */
+ unsigned int devno; /* 0 or 1 */
unsigned long flags; /* ATA_DFLAG_xxx */
+ /* n_sector is used as CLEAR_OFFSET, read comment above CLEAR_OFFSET */
+ u64 n_sectors; /* size of device, if ATA */
unsigned int class; /* ATA_DEV_xxx */
- unsigned int devno; /* 0 or 1 */
u16 id[ATA_ID_WORDS]; /* IDENTIFY xxx DEVICE data */
u8 pio_mode;
u8 dma_mode;
@@ -438,6 +440,11 @@ struct ata_device {
struct ata_ering ering;
};
+/* Offset into struct ata_device. Fields above it are maintained
+ * acress device init. Fields below are zeroed.
+ */
+#define ATA_DEVICE_CLEAR_OFFSET offsetof(struct ata_device, n_sectors)
+
struct ata_eh_info {
struct ata_device *dev; /* offending device */
u32 serror; /* SError from LLDD */
--
1.3.2
-
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