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profile: Convert to hotplug state machine
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Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs. A lot of code is removed because
the for-loop is used and create_hash_tables() is removed since its purpose
is covered by the startup / teardown hooks.

Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Signed-off-by: Anna-Maria Gleixner <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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Sebastian Andrzej Siewior authored and Ingo Molnar committed Jul 15, 2016
1 parent 24f73b9 commit e722d8d
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Showing 2 changed files with 66 additions and 116 deletions.
1 change: 1 addition & 0 deletions include/linux/cpuhotplug.h
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@ enum cpuhp_state {
CPUHP_X86_APB_DEAD,
CPUHP_WORKQUEUE_PREP,
CPUHP_HRTIMERS_PREPARE,
CPUHP_PROFILE_PREPARE,
CPUHP_TIMERS_DEAD,
CPUHP_NOTIFY_PREPARE,
CPUHP_BRINGUP_CPU,
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181 changes: 65 additions & 116 deletions kernel/profile.c
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Original file line number Diff line number Diff line change
Expand Up @@ -328,68 +328,57 @@ static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
put_cpu();
}

static int profile_cpu_callback(struct notifier_block *info,
unsigned long action, void *__cpu)
static int profile_dead_cpu(unsigned int cpu)
{
int node, cpu = (unsigned long)__cpu;
struct page *page;
int i;

switch (action) {
case CPU_UP_PREPARE:
case CPU_UP_PREPARE_FROZEN:
node = cpu_to_mem(cpu);
per_cpu(cpu_profile_flip, cpu) = 0;
if (!per_cpu(cpu_profile_hits, cpu)[1]) {
page = __alloc_pages_node(node,
GFP_KERNEL | __GFP_ZERO,
0);
if (!page)
return notifier_from_errno(-ENOMEM);
per_cpu(cpu_profile_hits, cpu)[1] = page_address(page);
}
if (!per_cpu(cpu_profile_hits, cpu)[0]) {
page = __alloc_pages_node(node,
GFP_KERNEL | __GFP_ZERO,
0);
if (!page)
goto out_free;
per_cpu(cpu_profile_hits, cpu)[0] = page_address(page);
}
break;
out_free:
page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
per_cpu(cpu_profile_hits, cpu)[1] = NULL;
__free_page(page);
return notifier_from_errno(-ENOMEM);
case CPU_ONLINE:
case CPU_ONLINE_FROZEN:
if (prof_cpu_mask != NULL)
cpumask_set_cpu(cpu, prof_cpu_mask);
break;
case CPU_UP_CANCELED:
case CPU_UP_CANCELED_FROZEN:
case CPU_DEAD:
case CPU_DEAD_FROZEN:
if (prof_cpu_mask != NULL)
cpumask_clear_cpu(cpu, prof_cpu_mask);
if (per_cpu(cpu_profile_hits, cpu)[0]) {
page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
per_cpu(cpu_profile_hits, cpu)[0] = NULL;
if (prof_cpu_mask != NULL)
cpumask_clear_cpu(cpu, prof_cpu_mask);

for (i = 0; i < 2; i++) {
if (per_cpu(cpu_profile_hits, cpu)[i]) {
page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[i]);
per_cpu(cpu_profile_hits, cpu)[i] = NULL;
__free_page(page);
}
if (per_cpu(cpu_profile_hits, cpu)[1]) {
page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
per_cpu(cpu_profile_hits, cpu)[1] = NULL;
__free_page(page);
}
return 0;
}

static int profile_prepare_cpu(unsigned int cpu)
{
int i, node = cpu_to_mem(cpu);
struct page *page;

per_cpu(cpu_profile_flip, cpu) = 0;

for (i = 0; i < 2; i++) {
if (per_cpu(cpu_profile_hits, cpu)[i])
continue;

page = __alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
if (!page) {
profile_dead_cpu(cpu);
return -ENOMEM;
}
break;
per_cpu(cpu_profile_hits, cpu)[i] = page_address(page);

}
return NOTIFY_OK;
return 0;
}

static int profile_online_cpu(unsigned int cpu)
{
if (prof_cpu_mask != NULL)
cpumask_set_cpu(cpu, prof_cpu_mask);

return 0;
}

#else /* !CONFIG_SMP */
#define profile_flip_buffers() do { } while (0)
#define profile_discard_flip_buffers() do { } while (0)
#define profile_cpu_callback NULL

static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
{
Expand Down Expand Up @@ -531,83 +520,43 @@ static const struct file_operations proc_profile_operations = {
.llseek = default_llseek,
};

#ifdef CONFIG_SMP
static void profile_nop(void *unused)
{
}

static int create_hash_tables(void)
int __ref create_proc_profile(void)
{
int cpu;

for_each_online_cpu(cpu) {
int node = cpu_to_mem(cpu);
struct page *page;

page = __alloc_pages_node(node,
GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE,
0);
if (!page)
goto out_cleanup;
per_cpu(cpu_profile_hits, cpu)[1]
= (struct profile_hit *)page_address(page);
page = __alloc_pages_node(node,
GFP_KERNEL | __GFP_ZERO | __GFP_THISNODE,
0);
if (!page)
goto out_cleanup;
per_cpu(cpu_profile_hits, cpu)[0]
= (struct profile_hit *)page_address(page);
}
return 0;
out_cleanup:
prof_on = 0;
smp_mb();
on_each_cpu(profile_nop, NULL, 1);
for_each_online_cpu(cpu) {
struct page *page;

if (per_cpu(cpu_profile_hits, cpu)[0]) {
page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
per_cpu(cpu_profile_hits, cpu)[0] = NULL;
__free_page(page);
}
if (per_cpu(cpu_profile_hits, cpu)[1]) {
page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
per_cpu(cpu_profile_hits, cpu)[1] = NULL;
__free_page(page);
}
}
return -1;
}
#else
#define create_hash_tables() ({ 0; })
struct proc_dir_entry *entry;
#ifdef CONFIG_SMP
enum cpuhp_state online_state;
#endif

int __ref create_proc_profile(void) /* false positive from hotcpu_notifier */
{
struct proc_dir_entry *entry;
int err = 0;

if (!prof_on)
return 0;

cpu_notifier_register_begin();

if (create_hash_tables()) {
err = -ENOMEM;
goto out;
}

#ifdef CONFIG_SMP
err = cpuhp_setup_state(CPUHP_PROFILE_PREPARE, "PROFILE_PREPARE",
profile_prepare_cpu, profile_dead_cpu);
if (err)
return err;

err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "AP_PROFILE_ONLINE",
profile_online_cpu, NULL);
if (err < 0)
goto err_state_prep;
online_state = err;
err = 0;
#endif
entry = proc_create("profile", S_IWUSR | S_IRUGO,
NULL, &proc_profile_operations);
if (!entry)
goto out;
goto err_state_onl;
proc_set_size(entry, (1 + prof_len) * sizeof(atomic_t));
__hotcpu_notifier(profile_cpu_callback, 0);

out:
cpu_notifier_register_done();
return err;
err_state_onl:
#ifdef CONFIG_SMP
cpuhp_remove_state(online_state);
err_state_prep:
cpuhp_remove_state(CPUHP_PROFILE_PREPARE);
#endif
return err;
}
subsys_initcall(create_proc_profile);
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