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Collapse aac_map_command() into aac_startio(). Check the AAC_QUEUE_FRZN in

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every iteration of aac_startio().  This ensures that a command that is
deferred for lack of resources doesn't immediately get retried in the
aac_startio() loop.  This avoids an almost certain livelock.
This commit is contained in:
Scott Long 2004-06-01 05:32:26 +00:00
parent f4d7361ecf
commit 397fa34f51
1 changed files with 31 additions and 43 deletions
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74
sys/dev/aac/aac.c
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@ -68,7 +68,6 @@ static void aac_get_bus_info(struct aac_softc *sc);
/* Command Processing */
static void aac_timeout(struct aac_softc *sc);
static int aac_map_command(struct aac_command *cm);
static void aac_complete(void *context, int pending);
static int aac_bio_command(struct aac_softc *sc, struct aac_command **cmp);
static void aac_bio_complete(struct aac_command *cm);
@ -654,13 +653,18 @@ void
aac_startio(struct aac_softc *sc)
{
struct aac_command *cm;
int error;
debug_called(2);
if (sc->flags & AAC_QUEUE_FRZN)
return;
for (;;) {
/*
* This flag might be set if the card is out of resources.
* Checking it here prevents an infinite loop of deferrals.
*/
if (sc->flags & AAC_QUEUE_FRZN)
break;
/*
* Try to get a command that's been put off for lack of
* resources
@ -678,49 +682,32 @@ aac_startio(struct aac_softc *sc)
if (cm == NULL)
break;
/* don't map more than once */
if (cm->cm_flags & AAC_CMD_MAPPED)
panic("aac: command %p already mapped", cm);
/*
* Try to give the command to the controller. Any error is
* catastrophic since it means that bus_dmamap_load() failed.
* Set up the command to go to the controller. If there are no
* data buffers associated with the command then it can bypass
* busdma.
*/
if (aac_map_command(cm) != 0)
panic("aac: error mapping command %p\n", cm);
if (cm->cm_datalen != 0) {
error = bus_dmamap_load(sc->aac_buffer_dmat,
cm->cm_datamap, cm->cm_data,
cm->cm_datalen,
aac_map_command_sg, cm, 0);
if (error == EINPROGRESS) {
debug(1, "freezing queue\n");
sc->flags |= AAC_QUEUE_FRZN;
error = 0;
} else
panic("aac_startio: unexpected error %d from "
"busdma\n", error);
} else
aac_map_command_sg(cm, NULL, 0, 0);
}
}
/*
* Deliver a command to the controller; allocate controller resources at the
* last moment when possible.
*/
static int
aac_map_command(struct aac_command *cm)
{
struct aac_softc *sc;
int error;
debug_called(2);
sc = cm->cm_sc;
error = 0;
/* don't map more than once */
if (cm->cm_flags & AAC_CMD_MAPPED)
panic("aac: command %p already mapped", cm);
if (cm->cm_datalen != 0) {
error = bus_dmamap_load(sc->aac_buffer_dmat, cm->cm_datamap,
cm->cm_data, cm->cm_datalen,
aac_map_command_sg, cm, 0);
if (error == EINPROGRESS) {
debug(1, "freezing queue\n");
sc->flags |= AAC_QUEUE_FRZN;
error = 0;
}
} else {
aac_map_command_sg(cm, NULL, 0, 0);
}
return (error);
}
/*
* Handle notification of one or more FIBs coming from the controller.
*/
@ -1285,9 +1272,10 @@ aac_map_command_sg(void *arg, bus_dma_segment_t *segs, int nseg, int error)
BUS_DMASYNC_PREWRITE);
cm->cm_flags |= AAC_CMD_MAPPED;
/* put the FIB on the outbound queue */
/* Put the FIB on the outbound queue */
if (aac_enqueue_fib(sc, cm->cm_queue, cm) == EBUSY) {
aac_unmap_command(cm);
sc->flags |= AAC_QUEUE_FRZN;
aac_requeue_ready(cm);
}