MIPS: MT: Fix FPU affinity.
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>
diff --git a/arch/mips/kernel/mips-mt-fpaff.c b/arch/mips/kernel/mips-mt-fpaff.c
index f5981c4..2340f11 100644
--- a/arch/mips/kernel/mips-mt-fpaff.c
+++ b/arch/mips/kernel/mips-mt-fpaff.c
@@ -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 @@
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 @@
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 @@
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;
+ cpumask_copy(&p->thread.user_cpus_allowed, new_mask);
- /* Unlock the task list */
- read_unlock(&tasklist_lock);
-
+ 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;