ide: use lock bitops for ports serialization (v2)
* Add ->host_busy field to struct ide_host and use it's first bit
together with lock bitops to provide new ports serialization method.
* Convert core IDE code to use new ide_[un]lock_host() helpers.
This removes the need for taking hwgroup->lock if host is already
busy on serialized hosts and makes it possible to merge ide_hwgroup_t
into ide_hwif_t (done in the later patch).
* Remove no longer needed ide_hwgroup_t.busy and ide_[un]lock_hwgroup().
* Update do_ide_request() documentation.
v2:
* ide_release_lock() should be called inside IDE_HFLAG_SERIALIZE check.
* Add ide_hwif_t.busy flag and ide_[un]lock_port() for serializing
devices on a port.
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/ide-io.c b/drivers/ide/ide-io.c
index 4ce793c..8f37182 100644
--- a/drivers/ide/ide-io.c
+++ b/drivers/ide/ide-io.c
@@ -666,45 +666,54 @@
}
EXPORT_SYMBOL(ide_stall_queue);
+static inline int ide_lock_port(ide_hwif_t *hwif)
+{
+ if (hwif->busy)
+ return 1;
+
+ hwif->busy = 1;
+
+ return 0;
+}
+
+static inline void ide_unlock_port(ide_hwif_t *hwif)
+{
+ hwif->busy = 0;
+}
+
+static inline int ide_lock_host(struct ide_host *host, ide_hwif_t *hwif)
+{
+ int rc = 0;
+
+ if (host->host_flags & IDE_HFLAG_SERIALIZE) {
+ rc = test_and_set_bit_lock(IDE_HOST_BUSY, &host->host_busy);
+ if (rc == 0) {
+ /* for atari only */
+ ide_get_lock(ide_intr, hwif);
+ }
+ }
+ return rc;
+}
+
+static inline void ide_unlock_host(struct ide_host *host)
+{
+ if (host->host_flags & IDE_HFLAG_SERIALIZE) {
+ /* for atari only */
+ ide_release_lock();
+ clear_bit_unlock(IDE_HOST_BUSY, &host->host_busy);
+ }
+}
+
/*
* Issue a new request to a drive from hwgroup
- *
- * A hwgroup is a serialized group of IDE interfaces. Usually there is
- * exactly one hwif (interface) per hwgroup, but buggy controllers (eg. CMD640)
- * may have both interfaces in a single hwgroup to "serialize" access.
- * Or possibly multiple ISA interfaces can share a common IRQ by being grouped
- * together into one hwgroup for serialized access.
- *
- * Note also that several hwgroups can end up sharing a single IRQ,
- * possibly along with many other devices. This is especially common in
- * PCI-based systems with off-board IDE controller cards.
- *
- * The IDE driver uses a per-hwgroup lock to protect the hwgroup->busy flag.
- *
- * The first thread into the driver for a particular hwgroup sets the
- * hwgroup->busy flag to indicate that this hwgroup is now active,
- * and then initiates processing of the top request from the request queue.
- *
- * Other threads attempting entry notice the busy setting, and will simply
- * queue their new requests and exit immediately. Note that hwgroup->busy
- * remains set even when the driver is merely awaiting the next interrupt.
- * Thus, the meaning is "this hwgroup is busy processing a request".
- *
- * When processing of a request completes, the completing thread or IRQ-handler
- * will start the next request from the queue. If no more work remains,
- * the driver will clear the hwgroup->busy flag and exit.
- *
- * The per-hwgroup spinlock is used to protect all access to the
- * hwgroup->busy flag, but is otherwise not needed for most processing in
- * the driver. This makes the driver much more friendlier to shared IRQs
- * than previous designs, while remaining 100% (?) SMP safe and capable.
*/
void do_ide_request(struct request_queue *q)
{
ide_drive_t *drive = q->queuedata;
ide_hwif_t *hwif = drive->hwif;
+ struct ide_host *host = hwif->host;
ide_hwgroup_t *hwgroup = hwif->hwgroup;
- struct request *rq;
+ struct request *rq = NULL;
ide_startstop_t startstop;
/*
@@ -721,9 +730,13 @@
blk_remove_plug(q);
spin_unlock_irq(q->queue_lock);
+
+ if (ide_lock_host(host, hwif))
+ goto plug_device_2;
+
spin_lock_irq(&hwgroup->lock);
- if (!ide_lock_hwgroup(hwgroup, hwif)) {
+ if (!ide_lock_port(hwif)) {
ide_hwif_t *prev_port;
repeat:
prev_port = hwif->host->cur_port;
@@ -731,7 +744,7 @@
if (drive->dev_flags & IDE_DFLAG_SLEEPING) {
if (time_before(drive->sleep, jiffies)) {
- ide_unlock_hwgroup(hwgroup);
+ ide_unlock_port(hwif);
goto plug_device;
}
}
@@ -761,7 +774,7 @@
spin_lock_irq(&hwgroup->lock);
if (!rq) {
- ide_unlock_hwgroup(hwgroup);
+ ide_unlock_port(hwif);
goto out;
}
@@ -782,7 +795,7 @@
blk_pm_request(rq) == 0 &&
(rq->cmd_flags & REQ_PREEMPT) == 0) {
/* there should be no pending command at this point */
- ide_unlock_hwgroup(hwgroup);
+ ide_unlock_port(hwif);
goto plug_device;
}
@@ -798,11 +811,15 @@
goto plug_device;
out:
spin_unlock_irq(&hwgroup->lock);
+ if (rq == NULL)
+ ide_unlock_host(host);
spin_lock_irq(q->queue_lock);
return;
plug_device:
spin_unlock_irq(&hwgroup->lock);
+ ide_unlock_host(host);
+plug_device_2:
spin_lock_irq(q->queue_lock);
if (!elv_queue_empty(q))
@@ -844,9 +861,9 @@
ide_dma_off_quietly(drive);
/*
- * un-busy drive etc (hwgroup->busy is cleared on return) and
- * make sure request is sane
+ * un-busy drive etc and make sure request is sane
*/
+
rq = HWGROUP(drive)->rq;
if (!rq)
@@ -895,6 +912,7 @@
void ide_timer_expiry (unsigned long data)
{
ide_hwgroup_t *hwgroup = (ide_hwgroup_t *) data;
+ ide_hwif_t *uninitialized_var(hwif);
ide_drive_t *uninitialized_var(drive);
ide_handler_t *handler;
ide_expiry_t *expiry;
@@ -918,7 +936,6 @@
printk(KERN_ERR "%s: ->cur_dev was NULL\n", __func__);
hwgroup->handler = NULL;
} else {
- ide_hwif_t *hwif;
ide_startstop_t startstop = ide_stopped;
if ((expiry = hwgroup->expiry) != NULL) {
@@ -964,15 +981,17 @@
spin_lock_irq(&hwgroup->lock);
enable_irq(hwif->irq);
if (startstop == ide_stopped) {
- ide_unlock_hwgroup(hwgroup);
+ ide_unlock_port(hwif);
plug_device = 1;
}
}
}
spin_unlock_irqrestore(&hwgroup->lock, flags);
- if (plug_device)
+ if (plug_device) {
+ ide_unlock_host(hwif->host);
ide_plug_device(drive);
+ }
}
/**
@@ -1150,7 +1169,7 @@
*/
if (startstop == ide_stopped) {
if (hwgroup->handler == NULL) { /* paranoia */
- ide_unlock_hwgroup(hwgroup);
+ ide_unlock_port(hwif);
plug_device = 1;
} else
printk(KERN_ERR "%s: %s: huh? expected NULL handler "
@@ -1161,8 +1180,10 @@
out:
spin_unlock_irqrestore(&hwgroup->lock, flags);
out_early:
- if (plug_device)
+ if (plug_device) {
+ ide_unlock_host(hwif->host);
ide_plug_device(drive);
+ }
return irq_ret;
}