Commit 0c6df6a6 authored by Greg Kroah-Hartman's avatar Greg Kroah-Hartman

IBM PCI Hotplug driver: polling thread locking cleanup

removed a lot of bizzare polling locking logic, causing the driver to not sleep
for 2 seconds with some locks held.  This improves userspace interaction by
a few orders of magnitude :)
parent 3da9cf28
......@@ -44,7 +44,7 @@
#define get_ctrl_revision(sl, rev) ibmphp_hpc_readslot (sl, READ_REVLEVEL, rev)
#define get_hpc_options(sl, opt) ibmphp_hpc_readslot (sl, READ_HPCOPTIONS, opt)
#define DRIVER_VERSION "0.2"
#define DRIVER_VERSION "0.3"
#define DRIVER_DESC "IBM Hot Plug PCI Controller Driver"
int ibmphp_debug;
......
......@@ -3,7 +3,7 @@
*
* Written By: Jyoti Shah, IBM Corporation
*
* Copyright (c) 2001,2001 IBM Corp.
* Copyright (c) 2001-2002 IBM Corp.
*
* All rights reserved.
*
......@@ -27,7 +27,6 @@
*
*/
//#include <linux/delay.h>
#include <linux/wait.h>
#include <linux/time.h>
#include <linux/module.h>
......@@ -35,9 +34,6 @@
#include <linux/smp_lock.h>
#include "ibmphp.h"
#define POLL_NO 0x01
#define POLL_YES 0x00
static int to_debug = FALSE;
#define debug_polling(fmt, arg...) do { if (to_debug) debug (fmt, arg); } while (0)
......@@ -98,19 +94,15 @@ static int to_debug = FALSE;
// if bits 20,22,25,26,27,29,30 are OFF return TRUE
#define HPC_I2CSTATUS_CHECK(s) ((u8)((s & 0x00000A76) ? FALSE : TRUE))
// return code 0:poll slots, 1-POLL_LATCH_CNT:poll latch register
#define INCREMENT_POLLCNT(i) ((i < POLL_LATCH_CNT) ? i++ : (i=0))
//----------------------------------------------------------------------------
// global variables
//----------------------------------------------------------------------------
static int ibmphp_shutdown;
static int tid_poll;
static int stop_polling; // 2 values: poll, don't poll
static struct semaphore sem_hpcaccess; // lock access to HPC
static struct semaphore semOperations; // lock all operations and
// access to data structures
static struct semaphore sem_exit; // make sure polling thread goes away
static struct semaphore sem_poll; // make sure poll is idle
//----------------------------------------------------------------------------
// local function prototypes
//----------------------------------------------------------------------------
......@@ -141,8 +133,6 @@ void ibmphp_hpc_initvars (void)
init_MUTEX (&sem_hpcaccess);
init_MUTEX (&semOperations);
init_MUTEX_LOCKED (&sem_exit);
init_MUTEX_LOCKED (&sem_poll);
stop_polling = POLL_YES;
to_debug = FALSE;
ibmphp_shutdown = FALSE;
tid_poll = 0;
......@@ -710,11 +700,6 @@ void free_hpc_access (void)
void ibmphp_lock_operations (void)
{
down (&semOperations);
stop_polling = POLL_NO;
to_debug = TRUE;
/* waiting for polling to actually stop */
down (&sem_poll);
}
/*----------------------------------------------------------------------
......@@ -723,8 +708,6 @@ void ibmphp_lock_operations (void)
void ibmphp_unlock_operations (void)
{
debug ("%s - Entry\n", __FUNCTION__);
stop_polling = POLL_YES;
to_debug = FALSE;
up (&semOperations);
debug ("%s - Exit\n", __FUNCTION__);
}
......@@ -732,34 +715,30 @@ void ibmphp_unlock_operations (void)
/*----------------------------------------------------------------------
* Name: poll_hpc()
*---------------------------------------------------------------------*/
#define POLL_LATCH_REGISTER 0
#define POLL_SLOTS 1
#define POLL_SLEEP 2
static void poll_hpc (void)
{
struct slot myslot, *pslot = NULL;
struct slot myslot;
struct slot *pslot = NULL;
struct list_head *pslotlist;
int rc;
int poll_state = POLL_LATCH_REGISTER;
u8 oldlatchlow = 0x00;
u8 curlatchlow = 0x00;
int pollcnt = 0;
int poll_count = 0;
u8 ctrl_count = 0x00;
debug ("poll_hpc - Entry\n");
debug ("%s - Entry\n", __FUNCTION__);
while (!ibmphp_shutdown) {
if (stop_polling) {
debug ("poll_hpc - stop_polling\n");
up (&sem_poll);
/* to prevent deadlock */
if (ibmphp_shutdown)
break;
/* to make the thread sleep */
/* try to get the lock to do some kind of harware access */
down (&semOperations);
up (&semOperations);
debug ("poll_hpc - after stop_polling sleep\n");
} else {
if (pollcnt) {
// only poll the latch register
oldlatchlow = curlatchlow;
switch (poll_state) {
case POLL_LATCH_REGISTER:
oldlatchlow = curlatchlow;
ctrl_count = 0x00;
list_for_each (pslotlist, &ibmphp_slot_head) {
if (ctrl_count >= ibmphp_get_total_controllers())
......@@ -773,14 +752,16 @@ static void poll_hpc (void)
&curlatchlow);
if (oldlatchlow != curlatchlow)
process_changeinlatch (oldlatchlow,
curlatchlow, pslot->ctrl);
curlatchlow,
pslot->ctrl);
}
}
}
} else {
list_for_each (pslotlist, &ibmphp_slot_head) {
if (stop_polling)
poll_state = POLL_SLOTS;
break;
case POLL_SLOTS:
list_for_each (pslotlist, &ibmphp_slot_head) {
pslot = list_entry (pslotlist, struct slot, ibm_slot_list);
// make a copy of the old status
memcpy ((void *) &myslot, (void *) pslot,
......@@ -791,14 +772,11 @@ static void poll_hpc (void)
process_changeinstatus (pslot, &myslot);
}
if (!stop_polling) {
ctrl_count = 0x00;
list_for_each (pslotlist, &ibmphp_slot_head) {
if (ctrl_count >= ibmphp_get_total_controllers())
break;
pslot =
list_entry (pslotlist, struct slot,
ibm_slot_list);
pslot = list_entry (pslotlist, struct slot, ibm_slot_list);
if (pslot->ctrl->ctlr_relative_id == ctrl_count) {
ctrl_count++;
if (READ_SLOT_LATCH (pslot->ctrl))
......@@ -807,15 +785,32 @@ static void poll_hpc (void)
&curlatchlow);
}
}
++poll_count;
if (poll_count >= POLL_LATCH_CNT) {
poll_count = 0;
poll_state = POLL_SLEEP;
}
break;
case POLL_SLEEP:
/* don't sleep with a lock on the hardware */
up (&semOperations);
long_delay (POLL_INTERVAL_SEC * HZ);
down (&semOperations);
poll_state = POLL_LATCH_REGISTER;
break;
}
INCREMENT_POLLCNT (pollcnt);
long_delay (POLL_INTERVAL_SEC * HZ); // snooze
}
/* give up the harware semaphore */
up (&semOperations);
/* sleep for a short time just for good measure */
set_current_state (TASK_INTERRUPTIBLE);
schedule_timeout (HZ/10);
}
up (&sem_poll);
up (&sem_exit);
debug ("poll_hpc - Exit\n");
debug ("%s - Exit\n", __FUNCTION__);
}
......@@ -1083,7 +1078,6 @@ void ibmphp_hpc_stop_poll_thread (void)
// cleanup
free_hpc_access ();
ibmphp_unlock_operations ();
up (&sem_poll);
up (&sem_exit);
debug ("ibmphp_hpc_stop_poll_thread - Exit\n");
......
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