[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: Keith Owens <kaos@sgi.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
This commit is contained in:
Keith Owens
Tony Luck
parent
15029285dc
commit
e026cca0f2
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@ -3,7 +3,7 @@
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*
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* Creates entries in /proc/sal for various system features.
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*
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* Copyright (c) 2003 Silicon Graphics, Inc. All rights reserved.
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* Copyright (c) 2003, 2006 Silicon Graphics, Inc. All rights reserved.
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* Copyright (c) 2003 Hewlett-Packard Co
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* Bjorn Helgaas <bjorn.helgaas@hp.com>
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*
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@ -27,9 +27,17 @@
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* mca.c may not pass a buffer, a NULL buffer just indicates that a new
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* record is available in SAL.
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* Replace some NR_CPUS by cpus_online, for hotplug cpu.
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*
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* Jan 5 2006 kaos@sgi.com
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* Handle hotplug cpus coming online.
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* Handle hotplug cpus going offline while they still have outstanding records.
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* Use the cpu_* macros consistently.
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* Replace the counting semaphore with a mutex and a test if the cpumask is non-empty.
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* Modify the locking to make the test for "work to do" an atomic operation.
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*/
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#include <linux/capability.h>
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#include <linux/cpu.h>
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#include <linux/types.h>
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#include <linux/proc_fs.h>
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#include <linux/module.h>
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@ -132,8 +140,8 @@ enum salinfo_state {
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};
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struct salinfo_data {
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volatile cpumask_t cpu_event; /* which cpus have outstanding events */
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struct semaphore sem; /* count of cpus with outstanding events (bits set in cpu_event) */
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cpumask_t cpu_event; /* which cpus have outstanding events */
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struct semaphore mutex;
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u8 *log_buffer;
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u64 log_size;
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u8 *oemdata; /* decoded oem data */
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@ -174,6 +182,21 @@ struct salinfo_platform_oemdata_parms {
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int ret;
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};
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/* Kick the mutex that tells user space that there is work to do. Instead of
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* trying to track the state of the mutex across multiple cpus, in user
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* context, interrupt context, non-maskable interrupt context and hotplug cpu,
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* it is far easier just to grab the mutex if it is free then release it.
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*
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* This routine must be called with data_saved_lock held, to make the down/up
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* operation atomic.
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*/
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static void
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salinfo_work_to_do(struct salinfo_data *data)
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{
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down_trylock(&data->mutex);
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up(&data->mutex);
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}
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static void
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salinfo_platform_oemdata_cpu(void *context)
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{
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@ -212,9 +235,9 @@ salinfo_log_wakeup(int type, u8 *buffer, u64 size, int irqsafe)
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BUG_ON(type >= ARRAY_SIZE(salinfo_log_name));
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if (irqsafe)
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spin_lock_irqsave(&data_saved_lock, flags);
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if (buffer) {
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if (irqsafe)
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spin_lock_irqsave(&data_saved_lock, flags);
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for (i = 0, data_saved = data->data_saved; i < saved_size; ++i, ++data_saved) {
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if (!data_saved->buffer)
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break;
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@ -232,13 +255,11 @@ salinfo_log_wakeup(int type, u8 *buffer, u64 size, int irqsafe)
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data_saved->size = size;
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data_saved->buffer = buffer;
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}
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if (irqsafe)
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spin_unlock_irqrestore(&data_saved_lock, flags);
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}
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if (!test_and_set_bit(smp_processor_id(), &data->cpu_event)) {
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if (irqsafe)
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up(&data->sem);
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cpu_set(smp_processor_id(), data->cpu_event);
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if (irqsafe) {
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salinfo_work_to_do(data);
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spin_unlock_irqrestore(&data_saved_lock, flags);
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}
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}
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@ -249,20 +270,17 @@ static struct timer_list salinfo_timer;
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static void
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salinfo_timeout_check(struct salinfo_data *data)
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{
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int i;
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unsigned long flags;
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if (!data->open)
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return;
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for_each_online_cpu(i) {
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if (test_bit(i, &data->cpu_event)) {
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/* double up() is not a problem, user space will see no
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* records for the additional "events".
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*/
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up(&data->sem);
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}
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if (!cpus_empty(data->cpu_event)) {
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spin_lock_irqsave(&data_saved_lock, flags);
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salinfo_work_to_do(data);
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spin_unlock_irqrestore(&data_saved_lock, flags);
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}
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}
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static void
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static void
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salinfo_timeout (unsigned long arg)
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{
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salinfo_timeout_check(salinfo_data + SAL_INFO_TYPE_MCA);
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@ -290,16 +308,20 @@ salinfo_event_read(struct file *file, char __user *buffer, size_t count, loff_t
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int i, n, cpu = -1;
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retry:
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if (down_trylock(&data->sem)) {
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if (cpus_empty(data->cpu_event) && down_trylock(&data->mutex)) {
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if (file->f_flags & O_NONBLOCK)
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return -EAGAIN;
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if (down_interruptible(&data->sem))
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if (down_interruptible(&data->mutex))
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return -EINTR;
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}
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n = data->cpu_check;
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for (i = 0; i < NR_CPUS; i++) {
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if (test_bit(n, &data->cpu_event) && cpu_online(n)) {
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if (cpu_isset(n, data->cpu_event)) {
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if (!cpu_online(n)) {
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cpu_clear(n, data->cpu_event);
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continue;
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}
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cpu = n;
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break;
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}
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@ -310,9 +332,6 @@ retry:
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if (cpu == -1)
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goto retry;
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/* events are sticky until the user says "clear" */
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up(&data->sem);
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/* for next read, start checking at next CPU */
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data->cpu_check = cpu;
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if (++data->cpu_check == NR_CPUS)
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@ -381,10 +400,8 @@ salinfo_log_release(struct inode *inode, struct file *file)
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static void
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call_on_cpu(int cpu, void (*fn)(void *), void *arg)
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{
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cpumask_t save_cpus_allowed, new_cpus_allowed;
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memcpy(&save_cpus_allowed, ¤t->cpus_allowed, sizeof(save_cpus_allowed));
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memset(&new_cpus_allowed, 0, sizeof(new_cpus_allowed));
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set_bit(cpu, &new_cpus_allowed);
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cpumask_t save_cpus_allowed = current->cpus_allowed;
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cpumask_t new_cpus_allowed = cpumask_of_cpu(cpu);
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set_cpus_allowed(current, new_cpus_allowed);
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(*fn)(arg);
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set_cpus_allowed(current, save_cpus_allowed);
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@ -433,10 +450,10 @@ retry:
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if (!data->saved_num)
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call_on_cpu(cpu, salinfo_log_read_cpu, data);
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if (!data->log_size) {
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data->state = STATE_NO_DATA;
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clear_bit(cpu, &data->cpu_event);
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data->state = STATE_NO_DATA;
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cpu_clear(cpu, data->cpu_event);
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} else {
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data->state = STATE_LOG_RECORD;
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data->state = STATE_LOG_RECORD;
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}
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}
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@ -473,27 +490,31 @@ static int
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salinfo_log_clear(struct salinfo_data *data, int cpu)
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{
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sal_log_record_header_t *rh;
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unsigned long flags;
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spin_lock_irqsave(&data_saved_lock, flags);
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data->state = STATE_NO_DATA;
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if (!test_bit(cpu, &data->cpu_event))
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return 0;
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down(&data->sem);
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clear_bit(cpu, &data->cpu_event);
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if (data->saved_num) {
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unsigned long flags;
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spin_lock_irqsave(&data_saved_lock, flags);
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shift1_data_saved(data, data->saved_num - 1 );
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data->saved_num = 0;
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if (!cpu_isset(cpu, data->cpu_event)) {
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spin_unlock_irqrestore(&data_saved_lock, flags);
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return 0;
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}
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cpu_clear(cpu, data->cpu_event);
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if (data->saved_num) {
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shift1_data_saved(data, data->saved_num - 1);
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data->saved_num = 0;
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}
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spin_unlock_irqrestore(&data_saved_lock, flags);
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rh = (sal_log_record_header_t *)(data->log_buffer);
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/* Corrected errors have already been cleared from SAL */
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if (rh->severity != sal_log_severity_corrected)
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call_on_cpu(cpu, salinfo_log_clear_cpu, data);
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/* clearing a record may make a new record visible */
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salinfo_log_new_read(cpu, data);
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if (data->state == STATE_LOG_RECORD &&
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!test_and_set_bit(cpu, &data->cpu_event))
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up(&data->sem);
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if (data->state == STATE_LOG_RECORD) {
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spin_lock_irqsave(&data_saved_lock, flags);
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cpu_set(cpu, data->cpu_event);
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salinfo_work_to_do(data);
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spin_unlock_irqrestore(&data_saved_lock, flags);
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}
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return 0;
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}
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@ -550,6 +571,53 @@ static struct file_operations salinfo_data_fops = {
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.write = salinfo_log_write,
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};
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#ifdef CONFIG_HOTPLUG_CPU
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static int __devinit
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salinfo_cpu_callback(struct notifier_block *nb, unsigned long action, void *hcpu)
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{
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unsigned int i, cpu = (unsigned long)hcpu;
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unsigned long flags;
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struct salinfo_data *data;
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switch (action) {
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case CPU_ONLINE:
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spin_lock_irqsave(&data_saved_lock, flags);
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for (i = 0, data = salinfo_data;
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i < ARRAY_SIZE(salinfo_data);
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++i, ++data) {
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cpu_set(cpu, data->cpu_event);
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salinfo_work_to_do(data);
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}
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spin_unlock_irqrestore(&data_saved_lock, flags);
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break;
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case CPU_DEAD:
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spin_lock_irqsave(&data_saved_lock, flags);
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for (i = 0, data = salinfo_data;
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i < ARRAY_SIZE(salinfo_data);
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++i, ++data) {
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struct salinfo_data_saved *data_saved;
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int j;
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for (j = ARRAY_SIZE(data->data_saved) - 1, data_saved = data->data_saved + j;
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j >= 0;
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--j, --data_saved) {
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if (data_saved->buffer && data_saved->cpu == cpu) {
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shift1_data_saved(data, j);
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}
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}
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cpu_clear(cpu, data->cpu_event);
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}
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spin_unlock_irqrestore(&data_saved_lock, flags);
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break;
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}
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return NOTIFY_OK;
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}
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static struct notifier_block salinfo_cpu_notifier =
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{
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.notifier_call = salinfo_cpu_callback,
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.priority = 0,
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};
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#endif /* CONFIG_HOTPLUG_CPU */
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static int __init
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salinfo_init(void)
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{
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@ -557,7 +625,7 @@ salinfo_init(void)
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struct proc_dir_entry **sdir = salinfo_proc_entries; /* keeps track of every entry */
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struct proc_dir_entry *dir, *entry;
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struct salinfo_data *data;
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int i, j, online;
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int i, j;
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salinfo_dir = proc_mkdir("sal", NULL);
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if (!salinfo_dir)
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@ -572,7 +640,7 @@ salinfo_init(void)
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for (i = 0; i < ARRAY_SIZE(salinfo_log_name); i++) {
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data = salinfo_data + i;
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data->type = i;
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sema_init(&data->sem, 0);
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init_MUTEX(&data->mutex);
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dir = proc_mkdir(salinfo_log_name[i], salinfo_dir);
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if (!dir)
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continue;
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@ -592,12 +660,8 @@ salinfo_init(void)
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*sdir++ = entry;
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/* we missed any events before now */
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online = 0;
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for_each_online_cpu(j) {
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set_bit(j, &data->cpu_event);
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++online;
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}
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sema_init(&data->sem, online);
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for_each_online_cpu(j)
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cpu_set(j, data->cpu_event);
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*sdir++ = dir;
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}
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@ -609,6 +673,10 @@ salinfo_init(void)
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salinfo_timer.function = &salinfo_timeout;
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add_timer(&salinfo_timer);
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#ifdef CONFIG_HOTPLUG_CPU
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register_cpu_notifier(&salinfo_cpu_notifier);
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#endif
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return 0;
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}
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