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ide: use lock bitops for ports serialization (v2)

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* 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>
This commit is contained in:
Bartlomiej Zolnierkiewicz 2009-01-06 17:20:49 +01:00
parent efe0397eef
commit 5b31f855f1
2 changed files with 69 additions and 71 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

105
drivers/ide/ide-io.c
View file

@ -666,45 +666,54 @@ void ide_stall_queue (ide_drive_t *drive, unsigned long timeout)
}
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 @@ void do_ide_request(struct request_queue *q)
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 @@ void do_ide_request(struct request_queue *q)
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 @@ void do_ide_request(struct request_queue *q)
spin_lock_irq(&hwgroup->lock);
if (!rq) {
ide_unlock_hwgroup(hwgroup);
ide_unlock_port(hwif);
goto out;
}
@ -782,7 +795,7 @@ void do_ide_request(struct request_queue *q)
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 @@ void do_ide_request(struct request_queue *q)
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 @@ static ide_startstop_t ide_dma_timeout_retry(ide_drive_t *drive, int error)
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 @@ static void ide_plug_device(ide_drive_t *drive)
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 @@ void ide_timer_expiry (unsigned long data)
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 @@ void ide_timer_expiry (unsigned long data)
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 @@ irqreturn_t ide_intr (int irq, void *dev_id)
*/
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 @@ irqreturn_t ide_intr (int irq, void *dev_id)
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;
}

35
include/linux/ide.h
View file

@ -828,6 +828,7 @@ typedef struct hwif_s {
unsigned present : 1; /* this interface exists */
unsigned sg_mapped : 1; /* sg_table and sg_nents are ready */
unsigned busy : 1; /* serializes devices on a port */
struct device gendev;
struct device *portdev;
@ -851,8 +852,13 @@ struct ide_host {
unsigned long host_flags;
void *host_priv;
ide_hwif_t *cur_port; /* for hosts requiring serialization */
/* used for hosts requiring serialization */
volatile long host_busy;
};
#define IDE_HOST_BUSY 0
/*
* internal ide interrupt handler type
*/
@ -866,8 +872,6 @@ typedef struct hwgroup_s {
/* irq handler, if active */
ide_startstop_t (*handler)(ide_drive_t *);
/* BOOL: protects all fields below */
volatile int busy;
/* BOOL: polling active & poll_timeout field valid */
unsigned int polling : 1;
@ -1271,26 +1275,6 @@ extern void ide_stall_queue(ide_drive_t *drive, unsigned long timeout);
extern void ide_timer_expiry(unsigned long);
extern irqreturn_t ide_intr(int irq, void *dev_id);
static inline int ide_lock_hwgroup(ide_hwgroup_t *hwgroup, ide_hwif_t *hwif)
{
if (hwgroup->busy)
return 1;
hwgroup->busy = 1;
/* for atari only */
ide_get_lock(ide_intr, hwif);
return 0;
}
static inline void ide_unlock_hwgroup(ide_hwgroup_t *hwgroup)
{
/* for atari only */
ide_release_lock();
hwgroup->busy = 0;
}
extern void do_ide_request(struct request_queue *);
void ide_init_disk(struct gendisk *, ide_drive_t *);
@ -1617,13 +1601,6 @@ static inline void ide_set_max_pio(ide_drive_t *drive)
extern spinlock_t ide_lock;
extern struct mutex ide_cfg_mtx;
/*
* Structure locking:
*
* ide_hwgroup_t->busy: hwgroup->lock
* ide_hwif_t->{hwgroup,mate}: constant, no locking
* ide_drive_t->hwif: constant, no locking
*/
#define local_irq_set(flags) do { local_save_flags((flags)); local_irq_enable_in_hardirq(); } while (0)