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@cn.fujitsu.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Rusty Russell <rusty@rustcorp.com.au> Acked-by: Mike Travis <travis@sgi.com> Cc: Paul Menage <menage@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Li Zefan
Linus Torvalds
Родитель
2341d1b659
Коммит
645fcc9d2f
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@ -415,6 +415,24 @@ static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)
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is_mem_exclusive(p) <= is_mem_exclusive(q);
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}
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/**
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* alloc_trial_cpuset - allocate a trial cpuset
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* @cs: the cpuset that the trial cpuset duplicates
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*/
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static struct cpuset *alloc_trial_cpuset(const struct cpuset *cs)
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{
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return kmemdup(cs, sizeof(*cs), GFP_KERNEL);
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}
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/**
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* free_trial_cpuset - free the trial cpuset
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* @trial: the trial cpuset to be freed
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*/
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static void free_trial_cpuset(struct cpuset *trial)
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{
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kfree(trial);
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}
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/*
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* validate_change() - Used to validate that any proposed cpuset change
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* follows the structural rules for cpusets.
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@ -880,10 +898,10 @@ static void update_tasks_cpumask(struct cpuset *cs, struct ptr_heap *heap)
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* @cs: the cpuset to consider
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* @buf: buffer of cpu numbers written to this cpuset
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*/
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static int update_cpumask(struct cpuset *cs, const char *buf)
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static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
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const char *buf)
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{
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struct ptr_heap heap;
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struct cpuset trialcs;
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int retval;
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int is_load_balanced;
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@ -891,8 +909,6 @@ static int update_cpumask(struct cpuset *cs, const char *buf)
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if (cs == &top_cpuset)
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return -EACCES;
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trialcs = *cs;
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/*
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* An empty cpus_allowed is ok only if the cpuset has no tasks.
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* Since cpulist_parse() fails on an empty mask, we special case
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@ -900,31 +916,31 @@ static int update_cpumask(struct cpuset *cs, const char *buf)
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* with tasks have cpus.
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*/
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if (!*buf) {
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cpus_clear(trialcs.cpus_allowed);
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cpus_clear(trialcs->cpus_allowed);
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} else {
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retval = cpulist_parse(buf, &trialcs.cpus_allowed);
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retval = cpulist_parse(buf, &trialcs->cpus_allowed);
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if (retval < 0)
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return retval;
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if (!cpus_subset(trialcs.cpus_allowed, cpu_online_map))
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if (!cpus_subset(trialcs->cpus_allowed, cpu_online_map))
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return -EINVAL;
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}
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retval = validate_change(cs, &trialcs);
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retval = validate_change(cs, trialcs);
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if (retval < 0)
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return retval;
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/* Nothing to do if the cpus didn't change */
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if (cpus_equal(cs->cpus_allowed, trialcs.cpus_allowed))
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if (cpus_equal(cs->cpus_allowed, trialcs->cpus_allowed))
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return 0;
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retval = heap_init(&heap, PAGE_SIZE, GFP_KERNEL, NULL);
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if (retval)
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return retval;
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is_load_balanced = is_sched_load_balance(&trialcs);
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is_load_balanced = is_sched_load_balance(trialcs);
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mutex_lock(&callback_mutex);
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cs->cpus_allowed = trialcs.cpus_allowed;
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cs->cpus_allowed = trialcs->cpus_allowed;
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mutex_unlock(&callback_mutex);
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/*
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@ -1099,9 +1115,9 @@ done:
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* lock each such tasks mm->mmap_sem, scan its vma's and rebind
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* their mempolicies to the cpusets new mems_allowed.
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*/
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static int update_nodemask(struct cpuset *cs, const char *buf)
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static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
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const char *buf)
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{
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struct cpuset trialcs;
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nodemask_t oldmem;
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int retval;
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@ -1112,8 +1128,6 @@ static int update_nodemask(struct cpuset *cs, const char *buf)
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if (cs == &top_cpuset)
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return -EACCES;
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trialcs = *cs;
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/*
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* An empty mems_allowed is ok iff there are no tasks in the cpuset.
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* Since nodelist_parse() fails on an empty mask, we special case
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@ -1121,27 +1135,27 @@ static int update_nodemask(struct cpuset *cs, const char *buf)
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* with tasks have memory.
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*/
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if (!*buf) {
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nodes_clear(trialcs.mems_allowed);
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nodes_clear(trialcs->mems_allowed);
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} else {
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retval = nodelist_parse(buf, trialcs.mems_allowed);
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retval = nodelist_parse(buf, trialcs->mems_allowed);
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if (retval < 0)
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goto done;
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if (!nodes_subset(trialcs.mems_allowed,
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if (!nodes_subset(trialcs->mems_allowed,
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node_states[N_HIGH_MEMORY]))
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return -EINVAL;
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}
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oldmem = cs->mems_allowed;
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if (nodes_equal(oldmem, trialcs.mems_allowed)) {
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if (nodes_equal(oldmem, trialcs->mems_allowed)) {
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retval = 0; /* Too easy - nothing to do */
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goto done;
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}
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retval = validate_change(cs, &trialcs);
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retval = validate_change(cs, trialcs);
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if (retval < 0)
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goto done;
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mutex_lock(&callback_mutex);
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cs->mems_allowed = trialcs.mems_allowed;
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cs->mems_allowed = trialcs->mems_allowed;
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cs->mems_generation = cpuset_mems_generation++;
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mutex_unlock(&callback_mutex);
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@ -1181,31 +1195,36 @@ static int update_relax_domain_level(struct cpuset *cs, s64 val)
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static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
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int turning_on)
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{
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struct cpuset trialcs;
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struct cpuset *trialcs;
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int err;
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int balance_flag_changed;
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trialcs = *cs;
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if (turning_on)
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set_bit(bit, &trialcs.flags);
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else
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clear_bit(bit, &trialcs.flags);
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trialcs = alloc_trial_cpuset(cs);
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if (!trialcs)
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return -ENOMEM;
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err = validate_change(cs, &trialcs);
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if (turning_on)
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set_bit(bit, &trialcs->flags);
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else
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clear_bit(bit, &trialcs->flags);
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err = validate_change(cs, trialcs);
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if (err < 0)
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return err;
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goto out;
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balance_flag_changed = (is_sched_load_balance(cs) !=
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is_sched_load_balance(&trialcs));
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is_sched_load_balance(trialcs));
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mutex_lock(&callback_mutex);
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cs->flags = trialcs.flags;
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cs->flags = trialcs->flags;
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mutex_unlock(&callback_mutex);
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if (!cpus_empty(trialcs.cpus_allowed) && balance_flag_changed)
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if (!cpus_empty(trialcs->cpus_allowed) && balance_flag_changed)
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async_rebuild_sched_domains();
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return 0;
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out:
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free_trial_cpuset(trialcs);
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return err;
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}
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/*
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@ -1453,21 +1472,29 @@ static int cpuset_write_resmask(struct cgroup *cgrp, struct cftype *cft,
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const char *buf)
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{
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int retval = 0;
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struct cpuset *cs = cgroup_cs(cgrp);
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struct cpuset *trialcs;
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if (!cgroup_lock_live_group(cgrp))
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return -ENODEV;
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trialcs = alloc_trial_cpuset(cs);
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if (!trialcs)
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return -ENOMEM;
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switch (cft->private) {
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case FILE_CPULIST:
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retval = update_cpumask(cgroup_cs(cgrp), buf);
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retval = update_cpumask(cs, trialcs, buf);
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break;
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case FILE_MEMLIST:
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retval = update_nodemask(cgroup_cs(cgrp), buf);
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retval = update_nodemask(cs, trialcs, buf);
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break;
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default:
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retval = -EINVAL;
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break;
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}
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free_trial_cpuset(trialcs);
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cgroup_unlock();
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return retval;
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}
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