Author: cem
Date: Mon Aug 22 14:51:07 2016
New Revision: 304602
URL: https://svnweb.freebsd.org/changeset/base/304602
Log:
ioat(4): Don't process events past queue head
Fix a race where the completion routine could overrun the active ring
area in some situations.
Modified:
head/sys/dev/ioat/ioat.c
Modified: head/sys/dev/ioat/ioat.c
==============================================================================
--- head/sys/dev/ioat/ioat.c Mon Aug 22 13:43:25 2016 (r304601)
+++ head/sys/dev/ioat/ioat.c Mon Aug 22 14:51:07 2016 (r304602)
@@ -678,19 +678,12 @@ ioat_process_events(struct ioat_softc *i
}
completed = 0;
- comp_update = *ioat->comp_update;
+ comp_update = ioat_get_chansts(ioat);
+ CTR4(KTR_IOAT, "%s channel=%u hw_status=0x%lx last_seen=0x%lx",
+ __func__, ioat->chan_idx, comp_update, ioat->last_seen);
status = comp_update & IOAT_CHANSTS_COMPLETED_DESCRIPTOR_MASK;
- if (status == ioat->last_seen) {
- /*
- * If we landed in process_events and nothing has been
- * completed, check for a timeout due to channel halt.
- */
- comp_update = ioat_get_chansts(ioat);
- goto out;
- }
-
- while (1) {
+ while (ioat_get_active(ioat) > 0) {
desc = ioat_get_ring_entry(ioat, ioat->tail);
dmadesc = &desc->bus_dmadesc;
CTR4(KTR_IOAT, "channel=%u completing desc %u ok cb %p(%p)",
@@ -704,17 +697,13 @@ ioat_process_events(struct ioat_softc *i
ioat->tail++;
if (desc->hw_desc_bus_addr == status)
break;
-
- KASSERT(ioat_get_active(ioat) > 0, ("overrunning ring t:%u "
- "h:%u st:0x%016lx last_seen:%016lx completed:%u\n",
- ioat->tail, ioat->head, comp_update, ioat->last_seen,
- completed));
}
- ioat->last_seen = desc->hw_desc_bus_addr;
- ioat->stats.descriptors_processed += completed;
+ if (completed != 0) {
+ ioat->last_seen = desc->hw_desc_bus_addr;
+ ioat->stats.descriptors_processed += completed;
+ }
-out:
ioat_write_chanctrl(ioat, IOAT_CHANCTRL_RUN);
/* Perform a racy check first; only take the locks if it passes. */
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