Revision 31bd61f2bb79e098117d823e054342b03aa87668 authored by Lachlan McIlroy on 17 September 2008, 06:45:37 UTC, committed by Lachlan McIlroy on 17 September 2008, 06:45:37 UTC
Memory allocations for log->l_grant_trace and iclog->ic_trace are done on demand when the first event is logged. In xlog_state_get_iclog_space() we call xlog_trace_iclog() under a spinlock and allocating memory here can cause us to sleep with a spinlock held and deadlock the system. For the log grant tracing we use KM_NOSLEEP but that means we can lose trace entries. Since there is no locking to serialize the log grant tracing we could race and have multiple allocations and leak memory. So move the allocations to where we initialize the log/iclog structures. Use KM_NOFS to avoid recursing into the filesystem and drop log->l_trace since it's not even used. SGI-PV: 983738 SGI-Modid: xfs-linux-melb:xfs-kern:31896a Signed-off-by: Lachlan McIlroy <lachlan@sgi.com> Signed-off-by: Christoph Hellwig <hch@infradead.org>
1 parent bc45eb8
percpu_counter.c
/*
* Fast batching percpu counters.
*/
#include <linux/percpu_counter.h>
#include <linux/notifier.h>
#include <linux/mutex.h>
#include <linux/init.h>
#include <linux/cpu.h>
#include <linux/module.h>
#ifdef CONFIG_HOTPLUG_CPU
static LIST_HEAD(percpu_counters);
static DEFINE_MUTEX(percpu_counters_lock);
#endif
void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
{
int cpu;
spin_lock(&fbc->lock);
for_each_possible_cpu(cpu) {
s32 *pcount = per_cpu_ptr(fbc->counters, cpu);
*pcount = 0;
}
fbc->count = amount;
spin_unlock(&fbc->lock);
}
EXPORT_SYMBOL(percpu_counter_set);
void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch)
{
s64 count;
s32 *pcount;
int cpu = get_cpu();
pcount = per_cpu_ptr(fbc->counters, cpu);
count = *pcount + amount;
if (count >= batch || count <= -batch) {
spin_lock(&fbc->lock);
fbc->count += count;
*pcount = 0;
spin_unlock(&fbc->lock);
} else {
*pcount = count;
}
put_cpu();
}
EXPORT_SYMBOL(__percpu_counter_add);
/*
* Add up all the per-cpu counts, return the result. This is a more accurate
* but much slower version of percpu_counter_read_positive()
*/
s64 __percpu_counter_sum(struct percpu_counter *fbc, int set)
{
s64 ret;
int cpu;
spin_lock(&fbc->lock);
ret = fbc->count;
for_each_online_cpu(cpu) {
s32 *pcount = per_cpu_ptr(fbc->counters, cpu);
ret += *pcount;
if (set)
*pcount = 0;
}
if (set)
fbc->count = ret;
spin_unlock(&fbc->lock);
return ret;
}
EXPORT_SYMBOL(__percpu_counter_sum);
static struct lock_class_key percpu_counter_irqsafe;
int percpu_counter_init(struct percpu_counter *fbc, s64 amount)
{
spin_lock_init(&fbc->lock);
fbc->count = amount;
fbc->counters = alloc_percpu(s32);
if (!fbc->counters)
return -ENOMEM;
#ifdef CONFIG_HOTPLUG_CPU
mutex_lock(&percpu_counters_lock);
list_add(&fbc->list, &percpu_counters);
mutex_unlock(&percpu_counters_lock);
#endif
return 0;
}
EXPORT_SYMBOL(percpu_counter_init);
int percpu_counter_init_irq(struct percpu_counter *fbc, s64 amount)
{
int err;
err = percpu_counter_init(fbc, amount);
if (!err)
lockdep_set_class(&fbc->lock, &percpu_counter_irqsafe);
return err;
}
void percpu_counter_destroy(struct percpu_counter *fbc)
{
if (!fbc->counters)
return;
free_percpu(fbc->counters);
fbc->counters = NULL;
#ifdef CONFIG_HOTPLUG_CPU
mutex_lock(&percpu_counters_lock);
list_del(&fbc->list);
mutex_unlock(&percpu_counters_lock);
#endif
}
EXPORT_SYMBOL(percpu_counter_destroy);
#ifdef CONFIG_HOTPLUG_CPU
static int __cpuinit percpu_counter_hotcpu_callback(struct notifier_block *nb,
unsigned long action, void *hcpu)
{
unsigned int cpu;
struct percpu_counter *fbc;
if (action != CPU_DEAD)
return NOTIFY_OK;
cpu = (unsigned long)hcpu;
mutex_lock(&percpu_counters_lock);
list_for_each_entry(fbc, &percpu_counters, list) {
s32 *pcount;
unsigned long flags;
spin_lock_irqsave(&fbc->lock, flags);
pcount = per_cpu_ptr(fbc->counters, cpu);
fbc->count += *pcount;
*pcount = 0;
spin_unlock_irqrestore(&fbc->lock, flags);
}
mutex_unlock(&percpu_counters_lock);
return NOTIFY_OK;
}
static int __init percpu_counter_startup(void)
{
hotcpu_notifier(percpu_counter_hotcpu_callback, 0);
return 0;
}
module_init(percpu_counter_startup);
#endif
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