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MIPS: MT: Fix FPU affinity.

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The fragile MT sys_sched_setaffinity wrapper needs its regular dose of
fixes.

Nose-poked-at-pile-o-crap-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Ralf Baechle 2010-05-29 03:19:57 +01:00
parent 1d84267480
commit 17c04139fd
1 changed files with 62 additions and 27 deletions
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89
arch/mips/kernel/mips-mt-fpaff.c
View File

@ -3,6 +3,7 @@
* Copyright (C) 2005 Mips Technologies, Inc
*/
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/cpumask.h>
#include <linux/delay.h>
#include <linux/kernel.h>
@ -39,6 +40,21 @@ static inline struct task_struct *find_process_by_pid(pid_t pid)
return pid ? find_task_by_vpid(pid) : current;
}
/*
* check the target process has a UID that matches the current process's
*/
static bool check_same_owner(struct task_struct *p)
{
const struct cred *cred = current_cred(), *pcred;
bool match;
rcu_read_lock();
pcred = __task_cred(p);
match = (cred->euid == pcred->euid ||
cred->euid == pcred->uid);
rcu_read_unlock();
return match;
}
/*
* mipsmt_sys_sched_setaffinity - set the cpu affinity of a process
@ -46,12 +62,10 @@ static inline struct task_struct *find_process_by_pid(pid_t pid)
asmlinkage long mipsmt_sys_sched_setaffinity(pid_t pid, unsigned int len,
unsigned long __user *user_mask_ptr)
{
cpumask_t new_mask;
cpumask_t effective_mask;
int retval;
struct task_struct *p;
cpumask_var_t cpus_allowed, new_mask, effective_mask;
struct thread_info *ti;
uid_t euid;
struct task_struct *p;
int retval;
if (len < sizeof(new_mask))
return -EINVAL;
@ -60,53 +74,74 @@ asmlinkage long mipsmt_sys_sched_setaffinity(pid_t pid, unsigned int len,
return -EFAULT;
get_online_cpus();
read_lock(&tasklist_lock);
rcu_read_lock();
p = find_process_by_pid(pid);
if (!p) {
read_unlock(&tasklist_lock);
rcu_read_unlock();
put_online_cpus();
return -ESRCH;
}
/*
* It is not safe to call set_cpus_allowed with the
* tasklist_lock held. We will bump the task_struct's
* usage count and drop tasklist_lock before invoking
* set_cpus_allowed.
*/
/* Prevent p going away */
get_task_struct(p);
rcu_read_unlock();
euid = current_euid();
retval = -EPERM;
if (euid != p->cred->euid && euid != p->cred->uid &&
!capable(CAP_SYS_NICE)) {
read_unlock(&tasklist_lock);
goto out_unlock;
if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
retval = -ENOMEM;
goto out_put_task;
}
if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
retval = -ENOMEM;
goto out_free_cpus_allowed;
}
if (!alloc_cpumask_var(&effective_mask, GFP_KERNEL)) {
retval = -ENOMEM;
goto out_free_new_mask;
}
retval = -EPERM;
if (!check_same_owner(p) && !capable(CAP_SYS_NICE))
goto out_unlock;
retval = security_task_setscheduler(p, 0, NULL);
if (retval)
goto out_unlock;
/* Record new user-specified CPU set for future reference */
p->thread.user_cpus_allowed = new_mask;
/* Unlock the task list */
read_unlock(&tasklist_lock);
cpumask_copy(&p->thread.user_cpus_allowed, new_mask);
again:
/* Compute new global allowed CPU set if necessary */
ti = task_thread_info(p);
if (test_ti_thread_flag(ti, TIF_FPUBOUND) &&
cpus_intersects(new_mask, mt_fpu_cpumask)) {
cpus_and(effective_mask, new_mask, mt_fpu_cpumask);
retval = set_cpus_allowed_ptr(p, &effective_mask);
cpus_intersects(*new_mask, mt_fpu_cpumask)) {
cpus_and(*effective_mask, *new_mask, mt_fpu_cpumask);
retval = set_cpus_allowed_ptr(p, effective_mask);
} else {
cpumask_copy(effective_mask, new_mask);
clear_ti_thread_flag(ti, TIF_FPUBOUND);
retval = set_cpus_allowed_ptr(p, &new_mask);
retval = set_cpus_allowed_ptr(p, new_mask);
}
if (!retval) {
cpuset_cpus_allowed(p, cpus_allowed);
if (!cpumask_subset(effective_mask, cpus_allowed)) {
/*
* We must have raced with a concurrent cpuset
* update. Just reset the cpus_allowed to the
* cpuset's cpus_allowed
*/
cpumask_copy(new_mask, cpus_allowed);
goto again;
}
}
out_unlock:
free_cpumask_var(effective_mask);
out_free_new_mask:
free_cpumask_var(new_mask);
out_free_cpus_allowed:
free_cpumask_var(cpus_allowed);
out_put_task:
put_task_struct(p);
put_online_cpus();
return retval;