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Subject[PATCH 03/12] cpumask: reduce stack pressure in sched_affinity
Remove local and passed cpumask_t variables in kernel/sched.c

Based on:
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git
git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-x86.git

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Jackson <pj@sgi.com>
Cc: Cliff Wickman <cpw@sgi.com>

Signed-off-by: Mike Travis <travis@sgi.com>
---
arch/x86/kernel/cpu/mcheck/mce_amd_64.c | 46 ++++++++++++++++----------------
include/linux/sched.h | 2 -
kernel/compat.c | 2 -
kernel/rcupreempt.c | 4 +-
kernel/sched.c | 5 ++-
5 files changed, 30 insertions(+), 29 deletions(-)
--- linux.trees.git.orig/arch/x86/kernel/cpu/mcheck/mce_amd_64.c
+++ linux.trees.git/arch/x86/kernel/cpu/mcheck/mce_amd_64.c
@@ -251,18 +251,18 @@ struct threshold_attr {
ssize_t(*store) (struct threshold_block *, const char *, size_t count);
};

-static cpumask_t affinity_set(unsigned int cpu)
+static void affinity_set(unsigned int cpu, cpumask_t *oldmask,
+ cpumask_t *newmask)
{
- cpumask_t oldmask = current->cpus_allowed;
- cpumask_t newmask = CPU_MASK_NONE;
- cpu_set(cpu, newmask);
- set_cpus_allowed(current, &newmask);
- return oldmask;
+ *oldmask = current->cpus_allowed;
+ *newmask = CPU_MASK_NONE;
+ cpu_set(cpu, *newmask);
+ set_cpus_allowed(current, newmask);
}

-static void affinity_restore(cpumask_t oldmask)
+static void affinity_restore(cpumask_t *oldmask)
{
- set_cpus_allowed(current, &oldmask);
+ set_cpus_allowed(current, oldmask);
}

#define SHOW_FIELDS(name) \
@@ -277,15 +277,15 @@ static ssize_t store_interrupt_enable(st
const char *buf, size_t count)
{
char *end;
- cpumask_t oldmask;
+ cpumask_t oldmask, newmask;
unsigned long new = simple_strtoul(buf, &end, 0);
if (end == buf)
return -EINVAL;
b->interrupt_enable = !!new;

- oldmask = affinity_set(b->cpu);
+ affinity_set(b->cpu, &oldmask, &newmask);
threshold_restart_bank(b, 0, 0);
- affinity_restore(oldmask);
+ affinity_restore(&oldmask);

return end - buf;
}
@@ -294,7 +294,7 @@ static ssize_t store_threshold_limit(str
const char *buf, size_t count)
{
char *end;
- cpumask_t oldmask;
+ cpumask_t oldmask, newmask;
u16 old;
unsigned long new = simple_strtoul(buf, &end, 0);
if (end == buf)
@@ -306,9 +306,9 @@ static ssize_t store_threshold_limit(str
old = b->threshold_limit;
b->threshold_limit = new;

- oldmask = affinity_set(b->cpu);
+ affinity_set(b->cpu, &oldmask, &newmask);
threshold_restart_bank(b, 0, old);
- affinity_restore(oldmask);
+ affinity_restore(&oldmask);

return end - buf;
}
@@ -316,10 +316,10 @@ static ssize_t store_threshold_limit(str
static ssize_t show_error_count(struct threshold_block *b, char *buf)
{
u32 high, low;
- cpumask_t oldmask;
- oldmask = affinity_set(b->cpu);
+ cpumask_t oldmask, newmask;
+ affinity_set(b->cpu, &oldmask, &newmask);
rdmsr(b->address, low, high);
- affinity_restore(oldmask);
+ affinity_restore(&oldmask);
return sprintf(buf, "%x\n",
(high & 0xFFF) - (THRESHOLD_MAX - b->threshold_limit));
}
@@ -327,10 +327,10 @@ static ssize_t show_error_count(struct t
static ssize_t store_error_count(struct threshold_block *b,
const char *buf, size_t count)
{
- cpumask_t oldmask;
- oldmask = affinity_set(b->cpu);
+ cpumask_t oldmask, newmask;
+ affinity_set(b->cpu, &oldmask, &newmask);
threshold_restart_bank(b, 1, 0);
- affinity_restore(oldmask);
+ affinity_restore(&oldmask);
return 1;
}

@@ -468,7 +468,7 @@ static __cpuinit int threshold_create_ba
{
int i, err = 0;
struct threshold_bank *b = NULL;
- cpumask_t oldmask = CPU_MASK_NONE;
+ cpumask_t oldmask = CPU_MASK_NONE, newmask;
char name[32];

sprintf(name, "threshold_bank%i", bank);
@@ -519,10 +519,10 @@ static __cpuinit int threshold_create_ba

per_cpu(threshold_banks, cpu)[bank] = b;

- oldmask = affinity_set(cpu);
+ affinity_set(cpu, &oldmask, &newmask);
err = allocate_threshold_blocks(cpu, bank, 0,
MSR_IA32_MC0_MISC + bank * 4);
- affinity_restore(oldmask);
+ affinity_restore(&oldmask);

if (err)
goto out_free;
--- linux.trees.git.orig/include/linux/sched.h
+++ linux.trees.git/include/linux/sched.h
@@ -2026,7 +2026,7 @@ static inline void arch_pick_mmap_layout
}
#endif

-extern long sched_setaffinity(pid_t pid, cpumask_t new_mask);
+extern long sched_setaffinity(pid_t pid, const cpumask_t *new_mask);
extern long sched_getaffinity(pid_t pid, cpumask_t *mask);

extern int sched_mc_power_savings, sched_smt_power_savings;
--- linux.trees.git.orig/kernel/compat.c
+++ linux.trees.git/kernel/compat.c
@@ -446,7 +446,7 @@ asmlinkage long compat_sys_sched_setaffi
if (retval)
return retval;

- return sched_setaffinity(pid, new_mask);
+ return sched_setaffinity(pid, &new_mask);
}

asmlinkage long compat_sys_sched_getaffinity(compat_pid_t pid, unsigned int len,
--- linux.trees.git.orig/kernel/rcupreempt.c
+++ linux.trees.git/kernel/rcupreempt.c
@@ -1007,10 +1007,10 @@ void __synchronize_sched(void)
if (sched_getaffinity(0, &oldmask) < 0)
oldmask = cpu_possible_map;
for_each_online_cpu(cpu) {
- sched_setaffinity(0, cpumask_of_cpu(cpu));
+ sched_setaffinity(0, &cpumask_of_cpu(cpu));
schedule();
}
- sched_setaffinity(0, oldmask);
+ sched_setaffinity(0, &oldmask);
}
EXPORT_SYMBOL_GPL(__synchronize_sched);

--- linux.trees.git.orig/kernel/sched.c
+++ linux.trees.git/kernel/sched.c
@@ -4706,9 +4706,10 @@ out_unlock:
return retval;
}

-long sched_setaffinity(pid_t pid, cpumask_t new_mask)
+long sched_setaffinity(pid_t pid, const cpumask_t *in_mask)
{
cpumask_t cpus_allowed;
+ cpumask_t new_mask = *in_mask;
struct task_struct *p;
int retval;

@@ -4789,7 +4790,7 @@ asmlinkage long sys_sched_setaffinity(pi
if (retval)
return retval;

- return sched_setaffinity(pid, new_mask);
+ return sched_setaffinity(pid, &new_mask);
}

/*
--


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