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libata: clean up EH speed down implementation
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Clean up EH speed down implementation.

* is_io boolean variable is replaced eflags.  is_io is ATA_EFLAG_IS_IO.

* Error categories now have names.

* Better comments.

* Reorder 5min and 10min rules in ata_eh_speed_down_verdict()

* Use local variable @link to cache @dev->link in ata_eh_speed_down()

These changes are to improve readability and ease further changes.
This patch doesn't introduce any behavior change.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
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Tejun Heo authored and Jeff Garzik committed Jan 23, 2008
1 parent 6f1d1e3 commit 3884f7b
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Showing 2 changed files with 74 additions and 45 deletions.
117 changes: 73 additions & 44 deletions drivers/ata/libata-eh.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -46,9 +46,20 @@
#include "libata.h"

enum {
/* speed down verdicts */
ATA_EH_SPDN_NCQ_OFF = (1 << 0),
ATA_EH_SPDN_SPEED_DOWN = (1 << 1),
ATA_EH_SPDN_FALLBACK_TO_PIO = (1 << 2),

/* error flags */
ATA_EFLAG_IS_IO = (1 << 0),

/* error categories */
ATA_ECAT_NONE = 0,
ATA_ECAT_ATA_BUS = 1,
ATA_ECAT_TOUT_HSM = 2,
ATA_ECAT_UNK_DEV = 3,
ATA_ECAT_NR = 4,
};

/* Waiting in ->prereset can never be reliable. It's sometimes nice
Expand Down Expand Up @@ -218,7 +229,7 @@ void ata_port_pbar_desc(struct ata_port *ap, int bar, ssize_t offset,

#endif /* CONFIG_PCI */

static void ata_ering_record(struct ata_ering *ering, int is_io,
static void ata_ering_record(struct ata_ering *ering, unsigned int eflags,
unsigned int err_mask)
{
struct ata_ering_entry *ent;
Expand All @@ -229,7 +240,7 @@ static void ata_ering_record(struct ata_ering *ering, int is_io,
ering->cursor %= ATA_ERING_SIZE;

ent = &ering->ring[ering->cursor];
ent->is_io = is_io;
ent->eflags = eflags;
ent->err_mask = err_mask;
ent->timestamp = get_jiffies_64();
}
Expand Down Expand Up @@ -1451,34 +1462,34 @@ static unsigned int ata_eh_analyze_tf(struct ata_queued_cmd *qc,
return action;
}

static int ata_eh_categorize_error(int is_io, unsigned int err_mask)
static int ata_eh_categorize_error(unsigned int eflags, unsigned int err_mask)
{
if (err_mask & AC_ERR_ATA_BUS)
return 1;
return ATA_ECAT_ATA_BUS;

if (err_mask & AC_ERR_TIMEOUT)
return 2;
return ATA_ECAT_TOUT_HSM;

if (is_io) {
if (eflags & ATA_EFLAG_IS_IO) {
if (err_mask & AC_ERR_HSM)
return 2;
return ATA_ECAT_TOUT_HSM;
if ((err_mask &
(AC_ERR_DEV|AC_ERR_MEDIA|AC_ERR_INVALID)) == AC_ERR_DEV)
return 3;
return ATA_ECAT_UNK_DEV;
}

return 0;
}

struct speed_down_verdict_arg {
u64 since;
int nr_errors[4];
int nr_errors[ATA_ECAT_NR];
};

static int speed_down_verdict_cb(struct ata_ering_entry *ent, void *void_arg)
{
struct speed_down_verdict_arg *arg = void_arg;
int cat = ata_eh_categorize_error(ent->is_io, ent->err_mask);
int cat = ata_eh_categorize_error(ent->eflags, ent->err_mask);

if (ent->timestamp < arg->since)
return -1;
Expand All @@ -1495,22 +1506,33 @@ static int speed_down_verdict_cb(struct ata_ering_entry *ent, void *void_arg)
* whether NCQ needs to be turned off, transfer speed should be
* stepped down, or falling back to PIO is necessary.
*
* Cat-1 is ATA_BUS error for any command.
* ECAT_ATA_BUS : ATA_BUS error for any command
*
* ECAT_TOUT_HSM : TIMEOUT for any command or HSM violation for
* IO commands
*
* ECAT_UNK_DEV : Unknown DEV error for IO commands
*
* Verdicts are
*
* Cat-2 is TIMEOUT for any command or HSM violation for known
* supported commands.
* NCQ_OFF : Turn off NCQ.
*
* Cat-3 is is unclassified DEV error for known supported
* command.
* SPEED_DOWN : Speed down transfer speed but don't fall back
* to PIO.
*
* NCQ needs to be turned off if there have been more than 3
* Cat-2 + Cat-3 errors during last 10 minutes.
* FALLBACK_TO_PIO : Fall back to PIO.
*
* Speed down is necessary if there have been more than 3 Cat-1 +
* Cat-2 errors or 10 Cat-3 errors during last 10 minutes.
* Even if multiple verdicts are returned, only one action is
* taken per error. ering is cleared after an action is taken.
*
* Falling back to PIO mode is necessary if there have been more
* than 10 Cat-1 + Cat-2 + Cat-3 errors during last 5 minutes.
* 1. If more than 10 ATA_BUS, TOUT_HSM or UNK_DEV errors
* ocurred during last 5 mins, FALLBACK_TO_PIO
*
* 2. If more than 3 TOUT_HSM or UNK_DEV errors occurred
* during last 10 mins, NCQ_OFF.
*
* 3. If more than 3 ATA_BUS or TOUT_HSM errors, or more than 10
* UNK_DEV errors occurred during last 10 mins, SPEED_DOWN.
*
* LOCKING:
* Inherited from caller.
Expand All @@ -1525,31 +1547,37 @@ static unsigned int ata_eh_speed_down_verdict(struct ata_device *dev)
struct speed_down_verdict_arg arg;
unsigned int verdict = 0;

/* scan past 10 mins of error history */
/* scan past 5 mins of error history */
memset(&arg, 0, sizeof(arg));
arg.since = j64 - min(j64, j10mins);
arg.since = j64 - min(j64, j5mins);
ata_ering_map(&dev->ering, speed_down_verdict_cb, &arg);

if (arg.nr_errors[2] + arg.nr_errors[3] > 3)
verdict |= ATA_EH_SPDN_NCQ_OFF;
if (arg.nr_errors[1] + arg.nr_errors[2] > 3 || arg.nr_errors[3] > 10)
verdict |= ATA_EH_SPDN_SPEED_DOWN;
if (arg.nr_errors[ATA_ECAT_ATA_BUS] +
arg.nr_errors[ATA_ECAT_TOUT_HSM] +
arg.nr_errors[ATA_ECAT_UNK_DEV] > 10)
verdict |= ATA_EH_SPDN_FALLBACK_TO_PIO;

/* scan past 3 mins of error history */
/* scan past 10 mins of error history */
memset(&arg, 0, sizeof(arg));
arg.since = j64 - min(j64, j5mins);
arg.since = j64 - min(j64, j10mins);
ata_ering_map(&dev->ering, speed_down_verdict_cb, &arg);

if (arg.nr_errors[1] + arg.nr_errors[2] + arg.nr_errors[3] > 10)
verdict |= ATA_EH_SPDN_FALLBACK_TO_PIO;
if (arg.nr_errors[ATA_ECAT_TOUT_HSM] +
arg.nr_errors[ATA_ECAT_UNK_DEV] > 3)
verdict |= ATA_EH_SPDN_NCQ_OFF;

if (arg.nr_errors[ATA_ECAT_ATA_BUS] +
arg.nr_errors[ATA_ECAT_TOUT_HSM] > 3 ||
arg.nr_errors[ATA_ECAT_UNK_DEV] > 10)
verdict |= ATA_EH_SPDN_SPEED_DOWN;

return verdict;
}

/**
* ata_eh_speed_down - record error and speed down if necessary
* @dev: Failed device
* @is_io: Did the device fail during normal IO?
* @eflags: mask of ATA_EFLAG_* flags
* @err_mask: err_mask of the error
*
* Record error and examine error history to determine whether
Expand All @@ -1563,18 +1591,19 @@ static unsigned int ata_eh_speed_down_verdict(struct ata_device *dev)
* RETURNS:
* Determined recovery action.
*/
static unsigned int ata_eh_speed_down(struct ata_device *dev, int is_io,
unsigned int err_mask)
static unsigned int ata_eh_speed_down(struct ata_device *dev,
unsigned int eflags, unsigned int err_mask)
{
struct ata_link *link = dev->link;
unsigned int verdict;
unsigned int action = 0;

/* don't bother if Cat-0 error */
if (ata_eh_categorize_error(is_io, err_mask) == 0)
if (ata_eh_categorize_error(eflags, err_mask) == 0)
return 0;

/* record error and determine whether speed down is necessary */
ata_ering_record(&dev->ering, is_io, err_mask);
ata_ering_record(&dev->ering, eflags, err_mask);
verdict = ata_eh_speed_down_verdict(dev);

/* turn off NCQ? */
Expand All @@ -1590,7 +1619,7 @@ static unsigned int ata_eh_speed_down(struct ata_device *dev, int is_io,
/* speed down? */
if (verdict & ATA_EH_SPDN_SPEED_DOWN) {
/* speed down SATA link speed if possible */
if (sata_down_spd_limit(dev->link) == 0) {
if (sata_down_spd_limit(link) == 0) {
action |= ATA_EH_HARDRESET;
goto done;
}
Expand Down Expand Up @@ -1621,7 +1650,7 @@ static unsigned int ata_eh_speed_down(struct ata_device *dev, int is_io,
* SATA. Consider it only for PATA.
*/
if ((verdict & ATA_EH_SPDN_FALLBACK_TO_PIO) && (dev->spdn_cnt >= 2) &&
(dev->link->ap->cbl != ATA_CBL_SATA) &&
(link->ap->cbl != ATA_CBL_SATA) &&
(dev->xfer_shift != ATA_SHIFT_PIO)) {
if (ata_down_xfermask_limit(dev, ATA_DNXFER_FORCE_PIO) == 0) {
dev->spdn_cnt = 0;
Expand Down Expand Up @@ -1653,8 +1682,8 @@ static void ata_eh_link_autopsy(struct ata_link *link)
struct ata_port *ap = link->ap;
struct ata_eh_context *ehc = &link->eh_context;
struct ata_device *dev;
unsigned int all_err_mask = 0;
int tag, is_io = 0;
unsigned int all_err_mask = 0, eflags = 0;
int tag;
u32 serror;
int rc;

Expand Down Expand Up @@ -1713,15 +1742,15 @@ static void ata_eh_link_autopsy(struct ata_link *link)
ehc->i.dev = qc->dev;
all_err_mask |= qc->err_mask;
if (qc->flags & ATA_QCFLAG_IO)
is_io = 1;
eflags |= ATA_EFLAG_IS_IO;
}

/* enforce default EH actions */
if (ap->pflags & ATA_PFLAG_FROZEN ||
all_err_mask & (AC_ERR_HSM | AC_ERR_TIMEOUT))
ehc->i.action |= ATA_EH_SOFTRESET;
else if ((is_io && all_err_mask) ||
(!is_io && (all_err_mask & ~AC_ERR_DEV)))
else if (((eflags & ATA_EFLAG_IS_IO) && all_err_mask) ||
(!(eflags & ATA_EFLAG_IS_IO) && (all_err_mask & ~AC_ERR_DEV)))
ehc->i.action |= ATA_EH_REVALIDATE;

/* If we have offending qcs and the associated failed device,
Expand All @@ -1744,7 +1773,7 @@ static void ata_eh_link_autopsy(struct ata_link *link)
dev = link->device;

if (dev)
ehc->i.action |= ata_eh_speed_down(dev, is_io, all_err_mask);
ehc->i.action |= ata_eh_speed_down(dev, eflags, all_err_mask);

DPRINTK("EXIT\n");
}
Expand Down
2 changes: 1 addition & 1 deletion include/linux/libata.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -482,7 +482,7 @@ struct ata_port_stats {
};

struct ata_ering_entry {
int is_io;
unsigned int eflags;
unsigned int err_mask;
u64 timestamp;
};
Expand Down

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