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Date: Wed, 31 Dec 2008 16:36:41 +0800
From: Li Zefan <lizf@...fujitsu.com>
To: Andrew Morton <akpm@...ux-foundation.org>
CC: Ingo Molnar <mingo@...e.hu>, Rusty Russell <rusty@...tcorp.com.au>,
Mike Travis <travis@....com>, Paul Menage <menage@...gle.com>,
LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 4/6] cpuset: don't allocate trial cpuset on stack
Impact: cleanups, reduce stack usage
This patch prepares for the next patch. When we convert cpuset.cpus_allowed
to cpumask_var_t, (trialcs = *cs) no longer works.
Another result of this patch is reducing stack usage of trialcs. sizeof(*cs)
can be as large as 148 bytes on x86_64, so it's really not good to have it
on stack.
Signed-off-by: Li Zefan <lizf@...fujitsu.com>
---
kernel/cpuset.c | 93 +++++++++++++++++++++++++++++++++++-------------------
1 files changed, 60 insertions(+), 33 deletions(-)
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index b4c36d5..480932a 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -415,6 +415,24 @@ static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)
is_mem_exclusive(p) <= is_mem_exclusive(q);
}
+/**
+ * alloc_trial_cpuset - allocate a trial cpuset
+ * @cs: the cpuset that the trial cpuset duplicates
+ */
+static struct cpuset *alloc_trial_cpuset(const struct cpuset *cs)
+{
+ return kmemdup(cs, sizeof(*cs), GFP_KERNEL);
+}
+
+/**
+ * free_trial_cpuset - free the trial cpuset
+ * @trial: the trial cpuset to be freed
+ */
+static void free_trial_cpuset(struct cpuset *trial)
+{
+ kfree(trial);
+}
+
/*
* validate_change() - Used to validate that any proposed cpuset change
* follows the structural rules for cpusets.
@@ -880,10 +898,10 @@ static void update_tasks_cpumask(struct cpuset *cs, struct ptr_heap *heap)
* @cs: the cpuset to consider
* @buf: buffer of cpu numbers written to this cpuset
*/
-static int update_cpumask(struct cpuset *cs, const char *buf)
+static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
+ const char *buf)
{
struct ptr_heap heap;
- struct cpuset trialcs;
int retval;
int is_load_balanced;
@@ -891,8 +909,6 @@ static int update_cpumask(struct cpuset *cs, const char *buf)
if (cs == &top_cpuset)
return -EACCES;
- trialcs = *cs;
-
/*
* An empty cpus_allowed is ok only if the cpuset has no tasks.
* Since cpulist_parse() fails on an empty mask, we special case
@@ -900,31 +916,31 @@ static int update_cpumask(struct cpuset *cs, const char *buf)
* with tasks have cpus.
*/
if (!*buf) {
- cpus_clear(trialcs.cpus_allowed);
+ cpus_clear(trialcs->cpus_allowed);
} else {
- retval = cpulist_parse(buf, &trialcs.cpus_allowed);
+ retval = cpulist_parse(buf, &trialcs->cpus_allowed);
if (retval < 0)
return retval;
- if (!cpus_subset(trialcs.cpus_allowed, cpu_online_map))
+ if (!cpus_subset(trialcs->cpus_allowed, cpu_online_map))
return -EINVAL;
}
- retval = validate_change(cs, &trialcs);
+ retval = validate_change(cs, trialcs);
if (retval < 0)
return retval;
/* Nothing to do if the cpus didn't change */
- if (cpus_equal(cs->cpus_allowed, trialcs.cpus_allowed))
+ if (cpus_equal(cs->cpus_allowed, trialcs->cpus_allowed))
return 0;
retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
if (retval)
return retval;
- is_load_balanced = is_sched_load_balance(&trialcs);
+ is_load_balanced = is_sched_load_balance(trialcs);
mutex_lock(&callback_mutex);
- cs->cpus_allowed = trialcs.cpus_allowed;
+ cs->cpus_allowed = trialcs->cpus_allowed;
mutex_unlock(&callback_mutex);
/*
@@ -1099,9 +1115,9 @@ done:
* lock each such tasks mm->mmap_sem, scan its vma's and rebind
* their mempolicies to the cpusets new mems_allowed.
*/
-static int update_nodemask(struct cpuset *cs, const char *buf)
+static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
+ const char *buf)
{
- struct cpuset trialcs;
nodemask_t oldmem;
int retval;
@@ -1112,8 +1128,6 @@ static int update_nodemask(struct cpuset *cs, const char *buf)
if (cs == &top_cpuset)
return -EACCES;
- trialcs = *cs;
-
/*
* An empty mems_allowed is ok iff there are no tasks in the cpuset.
* Since nodelist_parse() fails on an empty mask, we special case
@@ -1121,27 +1135,27 @@ static int update_nodemask(struct cpuset *cs, const char *buf)
* with tasks have memory.
*/
if (!*buf) {
- nodes_clear(trialcs.mems_allowed);
+ nodes_clear(trialcs->mems_allowed);
} else {
- retval = nodelist_parse(buf, trialcs.mems_allowed);
+ retval = nodelist_parse(buf, trialcs->mems_allowed);
if (retval < 0)
goto done;
- if (!nodes_subset(trialcs.mems_allowed,
+ if (!nodes_subset(trialcs->mems_allowed,
node_states[N_HIGH_MEMORY]))
return -EINVAL;
}
oldmem = cs->mems_allowed;
- if (nodes_equal(oldmem, trialcs.mems_allowed)) {
+ if (nodes_equal(oldmem, trialcs->mems_allowed)) {
retval = 0; /* Too easy - nothing to do */
goto done;
}
- retval = validate_change(cs, &trialcs);
+ retval = validate_change(cs, trialcs);
if (retval < 0)
goto done;
mutex_lock(&callback_mutex);
- cs->mems_allowed = trialcs.mems_allowed;
+ cs->mems_allowed = trialcs->mems_allowed;
cs->mems_generation = cpuset_mems_generation++;
mutex_unlock(&callback_mutex);
@@ -1181,31 +1195,36 @@ static int update_relax_domain_level(struct cpuset *cs, s64 val)
static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
int turning_on)
{
- struct cpuset trialcs;
+ struct cpuset *trialcs;
int err;
int balance_flag_changed;
- trialcs = *cs;
+ trialcs = alloc_trial_cpuset(cs);
+ if (!trialcs)
+ return -ENOMEM;
+
if (turning_on)
- set_bit(bit, &trialcs.flags);
+ set_bit(bit, &trialcs->flags);
else
- clear_bit(bit, &trialcs.flags);
+ clear_bit(bit, &trialcs->flags);
- err = validate_change(cs, &trialcs);
+ err = validate_change(cs, trialcs);
if (err < 0)
- return err;
+ goto out;
balance_flag_changed = (is_sched_load_balance(cs) !=
- is_sched_load_balance(&trialcs));
+ is_sched_load_balance(trialcs));
mutex_lock(&callback_mutex);
- cs->flags = trialcs.flags;
+ cs->flags = trialcs->flags;
mutex_unlock(&callback_mutex);
- if (!cpus_empty(trialcs.cpus_allowed) && balance_flag_changed)
+ if (!cpus_empty(trialcs->cpus_allowed) && balance_flag_changed)
async_rebuild_sched_domains();
- return 0;
+out:
+ free_trial_cpuset(trialcs);
+ return err;
}
/*
@@ -1471,21 +1490,29 @@ static int cpuset_write_resmask(struct cgroup *cgrp, struct cftype *cft,
const char *buf)
{
int retval = 0;
+ struct cpuset *cs = cgroup_cs(cgrp);
+ struct cpuset *trialcs;
if (!cgroup_lock_live_group(cgrp))
return -ENODEV;
+ trialcs = alloc_trial_cpuset(cs);
+ if (!trialcs)
+ return -ENOMEM;
+
switch (cft->private) {
case FILE_CPULIST:
- retval = update_cpumask(cgroup_cs(cgrp), buf);
+ retval = update_cpumask(cs, trialcs, buf);
break;
case FILE_MEMLIST:
- retval = update_nodemask(cgroup_cs(cgrp), buf);
+ retval = update_nodemask(cs, trialcs, buf);
break;
default:
retval = -EINVAL;
break;
}
+
+ free_trial_cpuset(trialcs);
cgroup_unlock();
return retval;
}
--
1.5.4.rc3
--
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