Improve kernel dumping reliability for busy ATA channels:

 - Generate fake channel interrupts even if channel busy with previous
request to let it finish. Without this, dumping requests were just queued
and never processed.
 - Drop pre-dump requests queue on dumping. ATA code, working in dumping
(interruptless) mode, unable to handle long request queue. Actually, to get
coherent dump we anyway should do as few unrelated actions as possible.

1 files changed, 24 insertions, 9 deletions

diff --git a/sys/dev/ata/ata-queue.c b/sys/dev/ata/ata-queue.c
index 4a4bb19..8756884 100644
--- a/sys/dev/ata/ata-queue.c
+++ b/sys/dev/ata/ata-queue.c
@@ -218,20 +218,17 @@ ata_start(device_t dev)
 		    ata_finish(request);
 		    return;
 		}
-		if (dumping) {
-		    mtx_unlock(&ch->state_mtx);
-		    mtx_unlock(&ch->queue_mtx);
-		    while (ch->running) {
-			ata_interrupt(ch);
-			DELAY(10);
-		    }
-		    return;
-		}       
 	    }
 	    mtx_unlock(&ch->state_mtx);
 	}
     }
     mtx_unlock(&ch->queue_mtx);
+    if (dumping) {
+	while (ch->running) {
+	    ata_interrupt(ch);
+	    DELAY(10);
+	}
+    }
 }
 
 void
@@ -560,6 +557,24 @@ ata_fail_requests(device_t dev)
     }
 }
 
+/*
+ * Rudely drop all requests queued to the channel of specified device.
+ * XXX: The requests are leaked, use only in fatal case.
+ */
+void
+ata_drop_requests(device_t dev)
+{
+    struct ata_channel *ch = device_get_softc(device_get_parent(dev));
+    struct ata_request *request, *tmp;
+
+    mtx_lock(&ch->queue_mtx);
+    TAILQ_FOREACH_SAFE(request, &ch->ata_queue, chain, tmp) {
+	TAILQ_REMOVE(&ch->ata_queue, request, chain);
+	request->result = ENXIO;
+    }
+    mtx_unlock(&ch->queue_mtx);
+}
+
 static u_int64_t
 ata_get_lba(struct ata_request *request)
 {