Commit e026cca0 authored by Keith Owens's avatar Keith Owens Committed by Tony Luck

[IA64] Add hotplug cpu to salinfo.c, replace semaphore with mutex

Add hotplug cpu support to salinfo.c.

The cpu_event field is a cpumask so use the cpu_* macros consistently,
replacing the existing mixture of cpu_* and *_bit macros.

Instead of counting the number of outstanding events in a semaphore and
trying to track that count over user space context, interrupt context,
non-maskable interrupt context and cpu hotplug, replace the semaphore
with a test for "any bits set" combined with a mutex.

Modify the locking to make the test for "work to do" an atomic
operation.
Signed-off-by: default avatarKeith Owens <kaos@sgi.com>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent 15029285
......@@ -3,7 +3,7 @@
*
* Creates entries in /proc/sal for various system features.
*
* Copyright (c) 2003 Silicon Graphics, Inc. All rights reserved.
* Copyright (c) 2003, 2006 Silicon Graphics, Inc. All rights reserved.
* Copyright (c) 2003 Hewlett-Packard Co
* Bjorn Helgaas <bjorn.helgaas@hp.com>
*
......@@ -27,9 +27,17 @@
* mca.c may not pass a buffer, a NULL buffer just indicates that a new
* record is available in SAL.
* Replace some NR_CPUS by cpus_online, for hotplug cpu.
*
* Jan 5 2006 kaos@sgi.com
* Handle hotplug cpus coming online.
* Handle hotplug cpus going offline while they still have outstanding records.
* Use the cpu_* macros consistently.
* Replace the counting semaphore with a mutex and a test if the cpumask is non-empty.
* Modify the locking to make the test for "work to do" an atomic operation.
*/
#include <linux/capability.h>
#include <linux/cpu.h>
#include <linux/types.h>
#include <linux/proc_fs.h>
#include <linux/module.h>
......@@ -132,8 +140,8 @@ enum salinfo_state {
};
struct salinfo_data {
volatile cpumask_t cpu_event; /* which cpus have outstanding events */
struct semaphore sem; /* count of cpus with outstanding events (bits set in cpu_event) */
cpumask_t cpu_event; /* which cpus have outstanding events */
struct semaphore mutex;
u8 *log_buffer;
u64 log_size;
u8 *oemdata; /* decoded oem data */
......@@ -174,6 +182,21 @@ struct salinfo_platform_oemdata_parms {
int ret;
};
/* Kick the mutex that tells user space that there is work to do. Instead of
* trying to track the state of the mutex across multiple cpus, in user
* context, interrupt context, non-maskable interrupt context and hotplug cpu,
* it is far easier just to grab the mutex if it is free then release it.
*
* This routine must be called with data_saved_lock held, to make the down/up
* operation atomic.
*/
static void
salinfo_work_to_do(struct salinfo_data *data)
{
down_trylock(&data->mutex);
up(&data->mutex);
}
static void
salinfo_platform_oemdata_cpu(void *context)
{
......@@ -212,9 +235,9 @@ salinfo_log_wakeup(int type, u8 *buffer, u64 size, int irqsafe)
BUG_ON(type >= ARRAY_SIZE(salinfo_log_name));
if (buffer) {
if (irqsafe)
spin_lock_irqsave(&data_saved_lock, flags);
if (buffer) {
for (i = 0, data_saved = data->data_saved; i < saved_size; ++i, ++data_saved) {
if (!data_saved->buffer)
break;
......@@ -232,13 +255,11 @@ salinfo_log_wakeup(int type, u8 *buffer, u64 size, int irqsafe)
data_saved->size = size;
data_saved->buffer = buffer;
}
if (irqsafe)
spin_unlock_irqrestore(&data_saved_lock, flags);
}
if (!test_and_set_bit(smp_processor_id(), &data->cpu_event)) {
if (irqsafe)
up(&data->sem);
cpu_set(smp_processor_id(), data->cpu_event);
if (irqsafe) {
salinfo_work_to_do(data);
spin_unlock_irqrestore(&data_saved_lock, flags);
}
}
......@@ -249,16 +270,13 @@ static struct timer_list salinfo_timer;
static void
salinfo_timeout_check(struct salinfo_data *data)
{
int i;
unsigned long flags;
if (!data->open)
return;
for_each_online_cpu(i) {
if (test_bit(i, &data->cpu_event)) {
/* double up() is not a problem, user space will see no
* records for the additional "events".
*/
up(&data->sem);
}
if (!cpus_empty(data->cpu_event)) {
spin_lock_irqsave(&data_saved_lock, flags);
salinfo_work_to_do(data);
spin_unlock_irqrestore(&data_saved_lock, flags);
}
}
......@@ -290,16 +308,20 @@ salinfo_event_read(struct file *file, char __user *buffer, size_t count, loff_t
int i, n, cpu = -1;
retry:
if (down_trylock(&data->sem)) {
if (cpus_empty(data->cpu_event) && down_trylock(&data->mutex)) {
if (file->f_flags & O_NONBLOCK)
return -EAGAIN;
if (down_interruptible(&data->sem))
if (down_interruptible(&data->mutex))
return -EINTR;
}
n = data->cpu_check;
for (i = 0; i < NR_CPUS; i++) {
if (test_bit(n, &data->cpu_event) && cpu_online(n)) {
if (cpu_isset(n, data->cpu_event)) {
if (!cpu_online(n)) {
cpu_clear(n, data->cpu_event);
continue;
}
cpu = n;
break;
}
......@@ -310,9 +332,6 @@ salinfo_event_read(struct file *file, char __user *buffer, size_t count, loff_t
if (cpu == -1)
goto retry;
/* events are sticky until the user says "clear" */
up(&data->sem);
/* for next read, start checking at next CPU */
data->cpu_check = cpu;
if (++data->cpu_check == NR_CPUS)
......@@ -381,10 +400,8 @@ salinfo_log_release(struct inode *inode, struct file *file)
static void
call_on_cpu(int cpu, void (*fn)(void *), void *arg)
{
cpumask_t save_cpus_allowed, new_cpus_allowed;
memcpy(&save_cpus_allowed, &current->cpus_allowed, sizeof(save_cpus_allowed));
memset(&new_cpus_allowed, 0, sizeof(new_cpus_allowed));
set_bit(cpu, &new_cpus_allowed);
cpumask_t save_cpus_allowed = current->cpus_allowed;
cpumask_t new_cpus_allowed = cpumask_of_cpu(cpu);
set_cpus_allowed(current, new_cpus_allowed);
(*fn)(arg);
set_cpus_allowed(current, save_cpus_allowed);
......@@ -434,7 +451,7 @@ salinfo_log_new_read(int cpu, struct salinfo_data *data)
call_on_cpu(cpu, salinfo_log_read_cpu, data);
if (!data->log_size) {
data->state = STATE_NO_DATA;
clear_bit(cpu, &data->cpu_event);
cpu_clear(cpu, data->cpu_event);
} else {
data->state = STATE_LOG_RECORD;
}
......@@ -473,27 +490,31 @@ static int
salinfo_log_clear(struct salinfo_data *data, int cpu)
{
sal_log_record_header_t *rh;
unsigned long flags;
spin_lock_irqsave(&data_saved_lock, flags);
data->state = STATE_NO_DATA;
if (!test_bit(cpu, &data->cpu_event))
if (!cpu_isset(cpu, data->cpu_event)) {
spin_unlock_irqrestore(&data_saved_lock, flags);
return 0;
down(&data->sem);
clear_bit(cpu, &data->cpu_event);
}
cpu_clear(cpu, data->cpu_event);
if (data->saved_num) {
unsigned long flags;
spin_lock_irqsave(&data_saved_lock, flags);
shift1_data_saved(data, data->saved_num - 1 );
shift1_data_saved(data, data->saved_num - 1);
data->saved_num = 0;
spin_unlock_irqrestore(&data_saved_lock, flags);
}
spin_unlock_irqrestore(&data_saved_lock, flags);
rh = (sal_log_record_header_t *)(data->log_buffer);
/* Corrected errors have already been cleared from SAL */
if (rh->severity != sal_log_severity_corrected)
call_on_cpu(cpu, salinfo_log_clear_cpu, data);
/* clearing a record may make a new record visible */
salinfo_log_new_read(cpu, data);
if (data->state == STATE_LOG_RECORD &&
!test_and_set_bit(cpu, &data->cpu_event))
up(&data->sem);
if (data->state == STATE_LOG_RECORD) {
spin_lock_irqsave(&data_saved_lock, flags);
cpu_set(cpu, data->cpu_event);
salinfo_work_to_do(data);
spin_unlock_irqrestore(&data_saved_lock, flags);
}
return 0;
}
......@@ -550,6 +571,53 @@ static struct file_operations salinfo_data_fops = {
.write = salinfo_log_write,
};
#ifdef CONFIG_HOTPLUG_CPU
static int __devinit
salinfo_cpu_callback(struct notifier_block *nb, unsigned long action, void *hcpu)
{
unsigned int i, cpu = (unsigned long)hcpu;
unsigned long flags;
struct salinfo_data *data;
switch (action) {
case CPU_ONLINE:
spin_lock_irqsave(&data_saved_lock, flags);
for (i = 0, data = salinfo_data;
i < ARRAY_SIZE(salinfo_data);
++i, ++data) {
cpu_set(cpu, data->cpu_event);
salinfo_work_to_do(data);
}
spin_unlock_irqrestore(&data_saved_lock, flags);
break;
case CPU_DEAD:
spin_lock_irqsave(&data_saved_lock, flags);
for (i = 0, data = salinfo_data;
i < ARRAY_SIZE(salinfo_data);
++i, ++data) {
struct salinfo_data_saved *data_saved;
int j;
for (j = ARRAY_SIZE(data->data_saved) - 1, data_saved = data->data_saved + j;
j >= 0;
--j, --data_saved) {
if (data_saved->buffer && data_saved->cpu == cpu) {
shift1_data_saved(data, j);
}
}
cpu_clear(cpu, data->cpu_event);
}
spin_unlock_irqrestore(&data_saved_lock, flags);
break;
}
return NOTIFY_OK;
}
static struct notifier_block salinfo_cpu_notifier =
{
.notifier_call = salinfo_cpu_callback,
.priority = 0,
};
#endif /* CONFIG_HOTPLUG_CPU */
static int __init
salinfo_init(void)
{
......@@ -557,7 +625,7 @@ salinfo_init(void)
struct proc_dir_entry **sdir = salinfo_proc_entries; /* keeps track of every entry */
struct proc_dir_entry *dir, *entry;
struct salinfo_data *data;
int i, j, online;
int i, j;
salinfo_dir = proc_mkdir("sal", NULL);
if (!salinfo_dir)
......@@ -572,7 +640,7 @@ salinfo_init(void)
for (i = 0; i < ARRAY_SIZE(salinfo_log_name); i++) {
data = salinfo_data + i;
data->type = i;
sema_init(&data->sem, 0);
init_MUTEX(&data->mutex);
dir = proc_mkdir(salinfo_log_name[i], salinfo_dir);
if (!dir)
continue;
......@@ -592,12 +660,8 @@ salinfo_init(void)
*sdir++ = entry;
/* we missed any events before now */
online = 0;
for_each_online_cpu(j) {
set_bit(j, &data->cpu_event);
++online;
}
sema_init(&data->sem, online);
for_each_online_cpu(j)
cpu_set(j, data->cpu_event);
*sdir++ = dir;
}
......@@ -609,6 +673,10 @@ salinfo_init(void)
salinfo_timer.function = &salinfo_timeout;
add_timer(&salinfo_timer);
#ifdef CONFIG_HOTPLUG_CPU
register_cpu_notifier(&salinfo_cpu_notifier);
#endif
return 0;
}
......
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