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Subject[PATCH 4/4] libata: Improve timeout handling
Date
From: Alan Cox <alan@redhat.com>

On a timeout call a device specific handler early in the recovery so that
we can complete and process successful commands which timed out due to IRQ
loss or the like rather more elegantly.

[Revised to exclude the timeout handling on a few devices that inherit from
SFF but are not SFF enough to use the default timeout handler]

Signed-off-by: Alan Cox <alan@redhat.com>
---
drivers/ata/libata-eh.c | 19 ++++++++++++++++--
drivers/ata/libata-sff.c | 46 +++++++++++++++++++++++++++++++++++++++++++-
drivers/ata/pata_isapnp.c | 12 ++++++++++-
drivers/ata/pdc_adma.c | 2 ++
drivers/ata/sata_mv.c | 2 ++
drivers/ata/sata_nv.c | 1 +
drivers/ata/sata_promise.c | 2 ++
drivers/ata/sata_qstor.c | 1 +
drivers/ata/sata_vsc.c | 3 +++
include/linux/libata.h | 2 ++
10 files changed, 85 insertions(+), 5 deletions(-)

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index ea89091..0183131 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -547,7 +547,7 @@ void ata_scsi_error(struct Scsi_Host *host)

/* For new EH, all qcs are finished in one of three ways -
* normal completion, error completion, and SCSI timeout.
- * Both cmpletions can race against SCSI timeout. When normal
+ * Both completions can race against SCSI timeout. When normal
* completion wins, the qc never reaches EH. When error
* completion wins, the qc has ATA_QCFLAG_FAILED set.
*
@@ -562,7 +562,19 @@ void ata_scsi_error(struct Scsi_Host *host)
int nr_timedout = 0;

spin_lock_irqsave(ap->lock, flags);
-
+
+ /* This must occur under the ap->lock as we don't want
+ a polled recovery to race the real interrupt handler
+
+ The lost_interrupt handler checks for any completed but
+ non-notified command and completes much like an IRQ handler.
+
+ We then fall into the error recovery code which will treat
+ this as if normal completion won the race */
+
+ if (ap->ops->lost_interrupt)
+ ap->ops->lost_interrupt(ap);
+
list_for_each_entry_safe(scmd, tmp, &host->eh_cmd_q, eh_entry) {
struct ata_queued_cmd *qc;

@@ -606,6 +618,9 @@ void ata_scsi_error(struct Scsi_Host *host)
ap->eh_tries = ATA_EH_MAX_TRIES;
} else
spin_unlock_wait(ap->lock);
+
+ /* If we timed raced normal completion and there is nothing to
+ recover nr_timedout == 0 why exactly are we doing error recovery ? */

repeat:
/* invoke error handler */
diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
index 9a10cb0..8332e97 100644
--- a/drivers/ata/libata-sff.c
+++ b/drivers/ata/libata-sff.c
@@ -65,6 +65,8 @@ const struct ata_port_operations ata_sff_port_ops = {
.sff_irq_on = ata_sff_irq_on,
.sff_irq_clear = ata_sff_irq_clear,

+ .lost_interrupt = ata_sff_lost_interrupt,
+
.port_start = ata_sff_port_start,
};
EXPORT_SYMBOL_GPL(ata_sff_port_ops);
@@ -1647,7 +1649,7 @@ EXPORT_SYMBOL_GPL(ata_sff_qc_fill_rtf);
* RETURNS:
* One if interrupt was handled, zero if not (shared irq).
*/
-inline unsigned int ata_sff_host_intr(struct ata_port *ap,
+unsigned int ata_sff_host_intr(struct ata_port *ap,
struct ata_queued_cmd *qc)
{
struct ata_eh_info *ehi = &ap->link.eh_info;
@@ -1776,6 +1778,48 @@ irqreturn_t ata_sff_interrupt(int irq, void *dev_instance)
EXPORT_SYMBOL_GPL(ata_sff_interrupt);

/**
+ * ata_sff_lost_interrupt - Check for an apparent lost interrupt
+ * @ap: port that appears to have timed out
+ *
+ * Called from the libata error handlers when the core code suspects
+ * an interrupt has been lost. If it has complete anything we can and
+ * then return. Interface must support altstatus for this faster
+ * recovery to occur.
+ *
+ * Locking:
+ * Caller holds host lock
+ */
+
+void ata_sff_lost_interrupt(struct ata_port *ap)
+{
+ u8 status;
+ struct ata_queued_cmd *qc;
+
+ /* Only one outstanding command per SFF channel */
+ qc = ata_qc_from_tag(ap, ap->link.active_tag);
+ /* Check we have a live one.. */
+ if (qc == NULL || !(qc->flags & ATA_QCFLAG_ACTIVE))
+ return;
+ /* We cannot lose an interrupt on a polled command */
+ if (qc->tf.flags & ATA_TFLAG_POLLING)
+ return;
+ /* See if the controller thinks it is still busy - if so the command
+ isn't a lost IRQ but is still in progress */
+ status = ata_sff_altstatus(ap);
+ if (status & ATA_BUSY)
+ return;
+
+ /* There was a command running, we are no longer busy and we have
+ no interrupt. */
+ ata_port_printk(ap, KERN_WARNING, "lost interrupt (Status 0x%x)\n",
+ status);
+ /* Run the host interrupt logic as if the interrupt had not been
+ lost */
+ ata_sff_host_intr(ap, qc);
+}
+EXPORT_SYMBOL_GPL(ata_sff_lost_interrupt);
+
+/**
* ata_sff_freeze - Freeze SFF controller port
* @ap: port to freeze
*
diff --git a/drivers/ata/pata_isapnp.c b/drivers/ata/pata_isapnp.c
index 15cdb91..eb50be8 100644
--- a/drivers/ata/pata_isapnp.c
+++ b/drivers/ata/pata_isapnp.c
@@ -17,7 +17,7 @@
#include <linux/libata.h>

#define DRV_NAME "pata_isapnp"
-#define DRV_VERSION "0.2.2"
+#define DRV_VERSION "0.2.5"

static struct scsi_host_template isapnp_sht = {
ATA_PIO_SHT(DRV_NAME),
@@ -28,6 +28,13 @@ static struct ata_port_operations isapnp_port_ops = {
.cable_detect = ata_cable_40wire,
};

+static struct ata_port_operations isapnp_noalt_port_ops = {
+ .inherits = &ata_sff_port_ops,
+ .cable_detect = ata_cable_40wire,
+ /* No altstatus so we don't want to use the lost interrupt poll */
+ .lost_interrupt = ATA_OP_NULL,
+};
+
/**
* isapnp_init_one - attach an isapnp interface
* @idev: PnP device
@@ -65,7 +72,7 @@ static int isapnp_init_one(struct pnp_dev *idev, const struct pnp_device_id *dev

ap = host->ports[0];

- ap->ops = &isapnp_port_ops;
+ ap->ops = &isapnp_noalt_port_ops;
ap->pio_mask = 1;
ap->flags |= ATA_FLAG_SLAVE_POSS;

@@ -76,6 +83,7 @@ static int isapnp_init_one(struct pnp_dev *idev, const struct pnp_device_id *dev
pnp_port_start(idev, 1), 1);
ap->ioaddr.altstatus_addr = ctl_addr;
ap->ioaddr.ctl_addr = ctl_addr;
+ ap->ops = &isapnp_port_ops;
}

ata_sff_std_ports(&ap->ioaddr);
diff --git a/drivers/ata/pdc_adma.c b/drivers/ata/pdc_adma.c
index be53545..51b4081 100644
--- a/drivers/ata/pdc_adma.c
+++ b/drivers/ata/pdc_adma.c
@@ -148,6 +148,8 @@ static struct scsi_host_template adma_ata_sht = {
static struct ata_port_operations adma_ata_ops = {
.inherits = &ata_sff_port_ops,

+ .lost_interrupt = ATA_OP_NULL,
+
.check_atapi_dma = adma_check_atapi_dma,
.qc_prep = adma_qc_prep,
.qc_issue = adma_qc_issue,
diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
index 74b1080..4110a29 100644
--- a/drivers/ata/sata_mv.c
+++ b/drivers/ata/sata_mv.c
@@ -566,6 +566,8 @@ static struct scsi_host_template mv6_sht = {
static struct ata_port_operations mv5_ops = {
.inherits = &ata_sff_port_ops,

+ .lost_interrupt = ATA_OP_NULL,
+
.qc_defer = mv_qc_defer,
.qc_prep = mv_qc_prep,
.qc_issue = mv_qc_issue,
diff --git a/drivers/ata/sata_nv.c b/drivers/ata/sata_nv.c
index f65b537..776e3dc 100644
--- a/drivers/ata/sata_nv.c
+++ b/drivers/ata/sata_nv.c
@@ -408,6 +408,7 @@ static struct scsi_host_template nv_swncq_sht = {

static struct ata_port_operations nv_common_ops = {
.inherits = &ata_bmdma_port_ops,
+ .lost_interrupt = ATA_OP_NULL,
.scr_read = nv_scr_read,
.scr_write = nv_scr_write,
};
diff --git a/drivers/ata/sata_promise.c b/drivers/ata/sata_promise.c
index ba9a257..7fe3da2 100644
--- a/drivers/ata/sata_promise.c
+++ b/drivers/ata/sata_promise.c
@@ -176,7 +176,9 @@ static const struct ata_port_operations pdc_common_ops = {
.check_atapi_dma = pdc_check_atapi_dma,
.qc_prep = pdc_qc_prep,
.qc_issue = pdc_qc_issue,
+
.sff_irq_clear = pdc_irq_clear,
+ .lost_interrupt = ATA_OP_NULL,

.post_internal_cmd = pdc_post_internal_cmd,
.error_handler = pdc_error_handler,
diff --git a/drivers/ata/sata_qstor.c b/drivers/ata/sata_qstor.c
index a000c86..7a9349a 100644
--- a/drivers/ata/sata_qstor.c
+++ b/drivers/ata/sata_qstor.c
@@ -147,6 +147,7 @@ static struct ata_port_operations qs_ata_ops = {
.softreset = ATA_OP_NULL,
.error_handler = qs_error_handler,
.post_internal_cmd = ATA_OP_NULL,
+ .lost_interrupt = ATA_OP_NULL,

.scr_read = qs_scr_read,
.scr_write = qs_scr_write,
diff --git a/drivers/ata/sata_vsc.c b/drivers/ata/sata_vsc.c
index c57cdff..07baeef 100644
--- a/drivers/ata/sata_vsc.c
+++ b/drivers/ata/sata_vsc.c
@@ -308,6 +308,9 @@ static struct scsi_host_template vsc_sata_sht = {

static struct ata_port_operations vsc_sata_ops = {
.inherits = &ata_bmdma_port_ops,
+ /* The IRQ handling is not quite standard SFF behaviour so we
+ cannot use the default lost interrupt handler */
+ .lost_interrupt = ATA_OP_NULL,
.sff_tf_load = vsc_sata_tf_load,
.sff_tf_read = vsc_sata_tf_read,
.freeze = vsc_freeze,
diff --git a/include/linux/libata.h b/include/linux/libata.h
index ffcef1f..ef2eda9 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -795,6 +795,7 @@ struct ata_port_operations {
ata_reset_fn_t pmp_hardreset;
ata_postreset_fn_t pmp_postreset;
void (*error_handler)(struct ata_port *ap);
+ void (*lost_interrupt)(struct ata_port *ap);
void (*post_internal_cmd)(struct ata_queued_cmd *qc);

/*
@@ -1574,6 +1575,7 @@ extern bool ata_sff_qc_fill_rtf(struct ata_queued_cmd *qc);
extern unsigned int ata_sff_host_intr(struct ata_port *ap,
struct ata_queued_cmd *qc);
extern irqreturn_t ata_sff_interrupt(int irq, void *dev_instance);
+extern void ata_sff_lost_interrupt(struct ata_port *ap);
extern void ata_sff_freeze(struct ata_port *ap);
extern void ata_sff_thaw(struct ata_port *ap);
extern int ata_sff_prereset(struct ata_link *link, unsigned long deadline);


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