From: viro@parcelfarce.linux.theplanet.co.uk
* fixed missing wakeups in ppa_pb_claim()/ppa_wakeup() - if the former had
been called just as current holder of port was giving it up, we could set
"I'm waiting" flag too late. Cleaned up the timeout logics.
---
25-akpm/drivers/scsi/ppa.c | 99 +++++++++++++++++++++++++++++----------------
1 files changed, 64 insertions(+), 35 deletions(-)
diff -puN drivers/scsi/ppa.c~PPA5-ppa_wakeup-RC1 drivers/scsi/ppa.c
--- 25/drivers/scsi/ppa.c~PPA5-ppa_wakeup-RC1 Wed Jan 14 13:35:49 2004
+++ 25-akpm/drivers/scsi/ppa.c Wed Jan 14 13:35:49 2004
@@ -31,7 +31,8 @@ typedef struct {
unsigned long jstart; /* Jiffies at start */
unsigned long recon_tmo; /* How many usecs to wait for reconnection (6th bit) */
unsigned int failed:1; /* Failure flag */
- unsigned int p_busy:1; /* Parport sharing busy flag */
+ unsigned wanted:1; /* Parport sharing busy flag */
+ wait_queue_head_t *waiting;
} ppa_struct;
#include "ppa.h"
@@ -44,33 +45,56 @@ static inline ppa_struct *ppa_dev(struct
return &ppa_hosts[host->unique_id];
}
+static spinlock_t arbitration_lock = SPIN_LOCK_UNLOCKED;
+
+static void got_it(ppa_struct *dev)
+{
+ dev->base = dev->dev->port->base;
+ if (dev->cur_cmd)
+ dev->cur_cmd->SCp.phase = 1;
+ else
+ wake_up(dev->waiting);
+}
+
static void ppa_wakeup(void *ref)
{
ppa_struct *dev = (ppa_struct *) ref;
+ unsigned long flags;
- if (!dev->p_busy)
- return;
-
- if (parport_claim(dev->dev)) {
- printk("ppa: bug in ppa_wakeup\n");
- return;
+ spin_lock_irqsave(&arbitration_lock, flags);
+ if (dev->wanted) {
+ parport_claim(dev->dev);
+ got_it(dev);
+ dev->wanted = 0;
}
- dev->p_busy = 0;
- dev->base = dev->dev->port->base;
- if (dev->cur_cmd)
- dev->cur_cmd->SCp.phase++;
+ spin_unlock_irqrestore(&arbitration_lock, flags);
return;
}
static int ppa_pb_claim(ppa_struct *dev)
{
- if (parport_claim(dev->dev)) {
- dev->p_busy = 1;
- return 1;
- }
- if (dev->cur_cmd)
- dev->cur_cmd->SCp.phase++;
- return 0;
+ unsigned long flags;
+ int res = 1;
+ spin_lock_irqsave(&arbitration_lock, flags);
+ if (parport_claim(dev->dev) == 0) {
+ got_it(dev);
+ res = 0;
+ }
+ dev->wanted = res;
+ spin_unlock_irqrestore(&arbitration_lock, flags);
+ return res;
+}
+
+static void ppa_pb_dismiss(ppa_struct *dev)
+{
+ unsigned long flags;
+ int wanted;
+ spin_lock_irqsave(&arbitration_lock, flags);
+ wanted = dev->wanted;
+ dev->wanted = 0;
+ spin_unlock_irqrestore(&arbitration_lock, flags);
+ if (!wanted)
+ parport_release(dev->dev);
}
static inline void ppa_pb_release(ppa_struct *dev)
@@ -90,6 +114,8 @@ static Scsi_Host_Template ppa_template;
static int ppa_probe(ppa_struct *dev, struct parport *pb)
{
struct Scsi_Host *host;
+ DECLARE_WAIT_QUEUE_HEAD(waiting);
+ DEFINE_WAIT(wait);
int ports;
int err;
int modes, ppb, ppb_hi;
@@ -97,6 +123,7 @@ static int ppa_probe(ppa_struct *dev, st
dev->base = -1;
dev->mode = PPA_AUTODETECT;
dev->recon_tmo = PPA_RECON_TMO;
+ init_waitqueue_head(&waiting);
dev->dev = parport_register_device(pb, "ppa", NULL, ppa_wakeup,
NULL, 0, dev);
@@ -107,19 +134,21 @@ static int ppa_probe(ppa_struct *dev, st
* registers. [ CTR and ECP ]
*/
err = -EBUSY;
- if (ppa_pb_claim(dev)) {
- unsigned long now = jiffies;
- while (dev->p_busy) {
- schedule(); /* We are safe to schedule here */
- if (time_after(jiffies, now + 3 * HZ)) {
- printk(KERN_ERR
- "ppa%d: failed to claim parport because a "
- "pardevice is owning the port for too longtime!\n",
- dev - ppa_hosts);
- goto out;
- }
- }
+ dev->waiting = &waiting;
+ prepare_to_wait(&waiting, &wait, TASK_UNINTERRUPTIBLE);
+ if (ppa_pb_claim(dev))
+ schedule_timeout(3 * HZ);
+ if (dev->wanted) {
+ printk(KERN_ERR "ppa%d: failed to claim parport because "
+ "a pardevice is owning the port for too long "
+ "time!\n", dev - ppa_hosts);
+ ppa_pb_dismiss(dev);
+ dev->waiting = NULL;
+ finish_wait(&waiting, &wait);
+ goto out;
}
+ dev->waiting = NULL;
+ finish_wait(&waiting, &wait);
ppb = dev->base = dev->dev->port->base;
ppb_hi = dev->dev->port->base_hi;
w_ctr(ppb, 0x0c);
@@ -759,8 +788,8 @@ static void ppa_interrupt(void *data)
if (cmd->SCp.phase > 1)
ppa_disconnect(dev);
- if (cmd->SCp.phase > 0)
- ppa_pb_release(dev);
+
+ ppa_pb_dismiss(dev);
dev->cur_cmd = 0;
@@ -784,7 +813,7 @@ static int ppa_engine(ppa_struct *dev, S
switch (cmd->SCp.phase) {
case 0: /* Phase 0 - Waiting for parport */
- if ((jiffies - dev->jstart) > HZ) {
+ if (time_after(jiffies, dev->jstart + HZ)) {
/*
* We waited more than a second
* for parport to call us
@@ -905,11 +934,11 @@ static int ppa_queuecommand(Scsi_Cmnd *c
cmd->result = DID_ERROR << 16; /* default return code */
cmd->SCp.phase = 0; /* bus free */
- ppa_pb_claim(dev);
-
dev->ppa_tq.data = dev;
schedule_work(&dev->ppa_tq);
+ ppa_pb_claim(dev);
+
return 0;
}
_