| Message ID | 4BA7253F.8070500@kernel.org |
|---|---|
| State | Not Applicable |
| Delegated to: | David Miller |
| Headers | show |
On 03/22/2010 04:07 AM, Tejun Heo wrote: > Commit 27943620cbd960f710a385ff4a538e14ed3f1922 introduced spurious > IRQ handling but it has a race condition where valid completion can be > lost while trying to clear spurious IRQ leading to occassional command > timeouts. > > This patch improves SFF interrupt handler such that > > 1. Once BMDMA HSM is stopped, the condition is never considered > spurious. As there's no way to resume stopped BMDMA HSM, if device > status doesn't agree with BMDMA status, the only way out is > aborting the command (otherwise, it will just end up timing out). > > 2. ap->ops->sff_check_status() can be safely called to clear spurious > device IRQ as it atomically returns completion status but BMDMA IRQ > status can't be cleared in safe way if command is in flight. After > a spurious IRQ, call ap->ops->sff_irq_clear() only if the > respective device is idle and retry completion if > sff_check_status() indicates command completion. > > Please note that ata_piix uses bmdma_status for sff_irq_check() and #2 > won't weaken spurious IRQ handling even with in-flight command because > if bmdma_status indicates IRQ pending but device status is not on > spurious check, the next IRQ handler invocation will abort the command > due to #1. > > This fixes bko#15537. > > https://bugzilla.kernel.org/show_bug.cgi?id=15537 > > Signed-off-by: Tejun Heo <tj@kernel.org> > Cc: Andrew Benton <b3nton@gmail.com> > Cc: Petr Uzel <petr.uzel@centrum.cz> > Cc: Rafael J. Wysocki <rjw@sisk.pl> > --- > drivers/ata/libata-sff.c | 43 +++++++++++++++++++++++++++++++++++-------- > 1 file changed, 35 insertions(+), 8 deletions(-) > > diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c > index 561dec2..66f6bd1 100644 > --- a/drivers/ata/libata-sff.c > +++ b/drivers/ata/libata-sff.c > @@ -1667,6 +1667,7 @@ unsigned int ata_sff_host_intr(struct ata_port *ap, > { > struct ata_eh_info *ehi = &ap->link.eh_info; > u8 status, host_stat = 0; > + bool bmdma_stopped = false; > > VPRINTK("ata%u: protocol %d task_state %d\n", > ap->print_id, qc->tf.protocol, ap->hsm_task_state); > @@ -1699,6 +1700,7 @@ unsigned int ata_sff_host_intr(struct ata_port *ap, > > /* before we do anything else, clear DMA-Start bit */ > ap->ops->bmdma_stop(qc); > + bmdma_stopped = true; > > if (unlikely(host_stat & ATA_DMA_ERR)) { > /* error when transfering data to/from memory */ > @@ -1716,8 +1718,14 @@ unsigned int ata_sff_host_intr(struct ata_port *ap, hmmmm, could you resend this patch? Neither git am nor patch(1) seem to like it... Jeff -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c index 561dec2..66f6bd1 100644 --- a/drivers/ata/libata-sff.c +++ b/drivers/ata/libata-sff.c @@ -1667,6 +1667,7 @@ unsigned int ata_sff_host_intr(struct ata_port *ap, { struct ata_eh_info *ehi = &ap->link.eh_info; u8 status, host_stat = 0; + bool bmdma_stopped = false; VPRINTK("ata%u: protocol %d task_state %d\n", ap->print_id, qc->tf.protocol, ap->hsm_task_state); @@ -1699,6 +1700,7 @@ unsigned int ata_sff_host_intr(struct ata_port *ap, /* before we do anything else, clear DMA-Start bit */ ap->ops->bmdma_stop(qc); + bmdma_stopped = true; if (unlikely(host_stat & ATA_DMA_ERR)) { /* error when transfering data to/from memory */ @@ -1716,8 +1718,14 @@ unsigned int ata_sff_host_intr(struct ata_port *ap, /* check main status, clearing INTRQ if needed */ status = ata_sff_irq_status(ap); - if (status & ATA_BUSY) - goto idle_irq; + if (status & ATA_BUSY) { + if (bmdma_stopped) { + /* BMDMA engine is already stopped, we're screwed */ + qc->err_mask |= AC_ERR_HSM; + ap->hsm_task_state = HSM_ST_ERR; + } else + goto idle_irq; + } /* ack bmdma irq events */ ap->ops->sff_irq_clear(ap); @@ -1762,13 +1770,15 @@ EXPORT_SYMBOL_GPL(ata_sff_host_intr); irqreturn_t ata_sff_interrupt(int irq, void *dev_instance) { struct ata_host *host = dev_instance; + bool retried = false; unsigned int i; - unsigned int handled = 0, polling = 0; + unsigned int handled, idle, polling; unsigned long flags; /* TODO: make _irqsave conditional on x86 PCI IDE legacy mode */ spin_lock_irqsave(&host->lock, flags); - +retry: + handled = idle = polling = 0; for (i = 0; i < host->n_ports; i++) { struct ata_port *ap = host->ports[i]; struct ata_queued_cmd *qc; @@ -1782,7 +1792,8 @@ irqreturn_t ata_sff_interrupt(int irq, void *dev_instance) handled |= ata_sff_host_intr(ap, qc); else polling |= 1 << i; - } + } else + idle |= 1 << i; } /* @@ -1790,7 +1801,9 @@ irqreturn_t ata_sff_interrupt(int irq, void *dev_instance) * asserting IRQ line, nobody cared will ensue. Check IRQ * pending status if available and clear spurious IRQ. */ - if (!handled) { + if (!handled && !retried) { + bool retry = false; + for (i = 0; i < host->n_ports; i++) { struct ata_port *ap = host->ports[i]; @@ -1805,8 +1818,22 @@ irqreturn_t ata_sff_interrupt(int irq, void *dev_instance) ata_port_printk(ap, KERN_INFO, "clearing spurious IRQ\n"); - ap->ops->sff_check_status(ap); - ap->ops->sff_irq_clear(ap); + if (idle & (1 << i)) { + ap->ops->sff_check_status(ap); + ap->ops->sff_irq_clear(ap); + } else { + /* clear INTRQ and check if BUSY cleared */ + if (!(ap->ops->sff_check_status(ap) & ATA_BUSY)) + retry |= true; + /* + * With command in flight, we can't do + * sff_irq_clear() w/o racing with completion. + */ + } + } + if (retry) { + retried = true; + goto retry; } }
Commit 27943620cbd960f710a385ff4a538e14ed3f1922 introduced spurious IRQ handling but it has a race condition where valid completion can be lost while trying to clear spurious IRQ leading to occassional command timeouts. This patch improves SFF interrupt handler such that 1. Once BMDMA HSM is stopped, the condition is never considered spurious. As there's no way to resume stopped BMDMA HSM, if device status doesn't agree with BMDMA status, the only way out is aborting the command (otherwise, it will just end up timing out). 2. ap->ops->sff_check_status() can be safely called to clear spurious device IRQ as it atomically returns completion status but BMDMA IRQ status can't be cleared in safe way if command is in flight. After a spurious IRQ, call ap->ops->sff_irq_clear() only if the respective device is idle and retry completion if sff_check_status() indicates command completion. Please note that ata_piix uses bmdma_status for sff_irq_check() and #2 won't weaken spurious IRQ handling even with in-flight command because if bmdma_status indicates IRQ pending but device status is not on spurious check, the next IRQ handler invocation will abort the command due to #1. This fixes bko#15537. https://bugzilla.kernel.org/show_bug.cgi?id=15537 Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andrew Benton <b3nton@gmail.com> Cc: Petr Uzel <petr.uzel@centrum.cz> Cc: Rafael J. Wysocki <rjw@sisk.pl> --- drivers/ata/libata-sff.c | 43 +++++++++++++++++++++++++++++++++++-------- 1 file changed, 35 insertions(+), 8 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html