atari_NCR5380: Refactor Falcon locking
Simplify falcon_release_lock_if_possible() by making callers responsible for
disabling local IRQ's, which they must do anyway to correctly synchronize
the ST DMA "lock" with core driver data structures. Move this
synchronization logic to the core driver with which it is tightly coupled.
Other LLD's like sun3_scsi and mac_scsi that can make use of this core
driver can just stub out the NCR5380_acquire_dma_irq() and
NCR5380_release_dma_irq() calls so the compiler will eliminate the
ST DMA code.
Remove a redundant local_irq_save/restore pair (irq's are disabled for
interrupt handlers these days). Revise the locking for
atari_scsi_bus_reset(): use local_irq_save/restore() instead of
atari_turnoff/turnon_irq(). There is no guarantee that atari_scsi still
holds the ST DMA lock during EH, so atari_turnoff/turnon_irq() could
end up dropping an IDE or floppy interrupt.
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
diff --git a/drivers/scsi/atari_NCR5380.c b/drivers/scsi/atari_NCR5380.c
index 371ca14..7955221 100644
--- a/drivers/scsi/atari_NCR5380.c
+++ b/drivers/scsi/atari_NCR5380.c
@@ -925,7 +925,7 @@
* because also a timer int can trigger an abort or reset, which would
* alter queues and touch the lock.
*/
- if (!falcon_get_lock())
+ if (!NCR5380_acquire_dma_irq(instance))
return SCSI_MLQUEUE_HOST_BUSY;
local_irq_save(flags);
@@ -960,6 +960,18 @@
return 0;
}
+static inline void maybe_release_dma_irq(struct Scsi_Host *instance)
+{
+ struct NCR5380_hostdata *hostdata = shost_priv(instance);
+
+ /* Caller does the locking needed to set & test these data atomically */
+ if (!hostdata->disconnected_queue &&
+ !hostdata->issue_queue &&
+ !hostdata->connected &&
+ !hostdata->retain_dma_intr)
+ NCR5380_release_dma_irq(instance);
+}
+
/*
* Function : NCR5380_main (void)
*
@@ -1082,9 +1094,11 @@
cmd_get_tag(tmp, tmp->cmnd[0] != REQUEST_SENSE);
#endif
if (!NCR5380_select(instance, tmp)) {
+ local_irq_disable();
hostdata->retain_dma_intr--;
/* release if target did not response! */
- falcon_release_lock_if_possible(hostdata);
+ maybe_release_dma_irq(instance);
+ local_irq_restore(flags);
break;
} else {
local_irq_disable();
@@ -2083,11 +2097,12 @@
case COMMAND_COMPLETE:
/* Accept message by clearing ACK */
NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE);
- /* ++guenther: possible race with Falcon locking */
- hostdata->retain_dma_intr++;
- hostdata->connected = NULL;
dprintk(NDEBUG_QUEUES, "scsi%d: command for target %d, lun %llu "
"completed\n", HOSTNO, cmd->device->id, cmd->device->lun);
+
+ local_irq_save(flags);
+ hostdata->retain_dma_intr++;
+ hostdata->connected = NULL;
#ifdef SUPPORT_TAGS
cmd_free_tag(cmd);
if (status_byte(cmd->SCp.Status) == QUEUE_FULL) {
@@ -2146,17 +2161,17 @@
dprintk(NDEBUG_AUTOSENSE, "scsi%d: performing request sense\n", HOSTNO);
- local_irq_save(flags);
LIST(cmd,hostdata->issue_queue);
SET_NEXT(cmd, hostdata->issue_queue);
hostdata->issue_queue = (struct scsi_cmnd *) cmd;
- local_irq_restore(flags);
dprintk(NDEBUG_QUEUES, "scsi%d: REQUEST SENSE added to head of "
"issue queue\n", H_NO(cmd));
} else {
cmd->scsi_done(cmd);
}
+ local_irq_restore(flags);
+
NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
/*
* Restore phase bits to 0 so an interrupted selection,
@@ -2167,12 +2182,14 @@
while ((NCR5380_read(STATUS_REG) & SR_BSY) && !hostdata->connected)
barrier();
+ local_irq_save(flags);
hostdata->retain_dma_intr--;
/* ++roman: For Falcon SCSI, release the lock on the
* ST-DMA here if no other commands are waiting on the
* disconnected queue.
*/
- falcon_release_lock_if_possible(hostdata);
+ maybe_release_dma_irq(instance);
+ local_irq_restore(flags);
return;
case MESSAGE_REJECT:
/* Accept message by clearing ACK */
@@ -2331,6 +2348,7 @@
hostdata->last_message = msgout;
NCR5380_transfer_pio(instance, &phase, &len, &data);
if (msgout == ABORT) {
+ local_irq_save(flags);
#ifdef SUPPORT_TAGS
cmd_free_tag(cmd);
#else
@@ -2338,9 +2356,10 @@
#endif
hostdata->connected = NULL;
cmd->result = DID_ERROR << 16;
- cmd->scsi_done(cmd);
NCR5380_write(SELECT_ENABLE_REG, hostdata->id_mask);
- falcon_release_lock_if_possible(hostdata);
+ maybe_release_dma_irq(instance);
+ local_irq_restore(flags);
+ cmd->scsi_done(cmd);
return;
}
msgout = NOP;
@@ -2393,7 +2412,6 @@
unsigned char msg[3];
unsigned char *data;
struct scsi_cmnd *tmp = NULL, *prev;
-/* unsigned long flags; */
/*
* Disable arbitration, etc. since the host adapter obviously
@@ -2473,8 +2491,6 @@
&& (tag == tmp->tag)
#endif
) {
- /* ++guenther: prevent race with falcon_release_lock */
- hostdata->retain_dma_intr++;
if (prev) {
REMOVE(prev, NEXT(prev), tmp, NEXT(tmp));
SET_NEXT(prev, NEXT(tmp));
@@ -2512,7 +2528,6 @@
hostdata->connected = tmp;
dprintk(NDEBUG_RESELECTION, "scsi%d: nexus established, target = %d, lun = %llu, tag = %d\n",
HOSTNO, tmp->device->id, tmp->device->lun, tmp->tag);
- hostdata->retain_dma_intr--;
}
@@ -2587,12 +2602,12 @@
#else
hostdata->busy[cmd->device->id] &= ~(1 << cmd->device->lun);
#endif
+ maybe_release_dma_irq(instance);
local_irq_restore(flags);
cmd->scsi_done(cmd);
- falcon_release_lock_if_possible(hostdata);
return SUCCESS;
} else {
-/* local_irq_restore(flags); */
+ local_irq_restore(flags);
printk("scsi%d: abort of connected command failed!\n", HOSTNO);
return FAILED;
}
@@ -2611,13 +2626,13 @@
(*prev) = NEXT(tmp);
SET_NEXT(tmp, NULL);
tmp->result = DID_ABORT << 16;
+ maybe_release_dma_irq(instance);
local_irq_restore(flags);
dprintk(NDEBUG_ABORT, "scsi%d: abort removed command from issue queue.\n",
HOSTNO);
/* Tagged queuing note: no tag to free here, hasn't been assigned
* yet... */
tmp->scsi_done(tmp);
- falcon_release_lock_if_possible(hostdata);
return SUCCESS;
}
}
@@ -2695,15 +2710,22 @@
#else
hostdata->busy[cmd->device->id] &= ~(1 << cmd->device->lun);
#endif
+ maybe_release_dma_irq(instance);
local_irq_restore(flags);
tmp->scsi_done(tmp);
- falcon_release_lock_if_possible(hostdata);
return SUCCESS;
}
}
}
}
+ /* Maybe it is sufficient just to release the ST-DMA lock... (if
+ * possible at all) At least, we should check if the lock could be
+ * released after the abort, in case it is kept due to some bug.
+ */
+ maybe_release_dma_irq(instance);
+ local_irq_restore(flags);
+
/*
* Case 5 : If we reached this point, the command was not found in any of
* the queues.
@@ -2714,15 +2736,8 @@
* broke.
*/
- local_irq_restore(flags);
printk(KERN_INFO "scsi%d: warning : SCSI command probably completed successfully before abortion\n", HOSTNO);
- /* Maybe it is sufficient just to release the ST-DMA lock... (if
- * possible at all) At least, we should check if the lock could be
- * released after the abort, in case it is kept due to some bug.
- */
- falcon_release_lock_if_possible(hostdata);
-
return FAILED;
}
@@ -2738,14 +2753,15 @@
static int NCR5380_bus_reset(struct scsi_cmnd *cmd)
{
- SETUP_HOSTDATA(cmd->device->host);
+ struct Scsi_Host *instance = cmd->device->host;
+ struct NCR5380_hostdata *hostdata = shost_priv(instance);
int i;
unsigned long flags;
#if defined(RESET_RUN_DONE)
struct scsi_cmnd *connected, *disconnected_queue;
#endif
- NCR5380_print_status(cmd->device->host);
+ NCR5380_print_status(instance);
/* get in phase */
NCR5380_write(TARGET_COMMAND_REG,
@@ -2870,6 +2886,8 @@
#ifdef REAL_DMA
hostdata->dma_len = 0;
#endif
+
+ maybe_release_dma_irq(instance);
local_irq_restore(flags);
/* we did no complete reset of all commands, so a wakeup is required */