PageRenderTime 536ms CodeModel.GetById 93ms app.highlight 11ms RepoModel.GetById 0ms app.codeStats 1ms

/arch/mips/kernel/mips-mt-fpaff.c

https://bitbucket.org/thekraven/iscream_thunderc-2.6.35
C | 214 lines | 146 code | 28 blank | 40 comment | 22 complexity | 72df9bdd43cf679c262ee6446fc34f87 MD5 | raw file
Possible License(s): GPL-2.0, LGPL-2.0, AGPL-1.0
  1/*
  2 * General MIPS MT support routines, usable in AP/SP, SMVP, or SMTC kernels
  3 * Copyright (C) 2005 Mips Technologies, Inc
  4 */
  5#include <linux/cpu.h>
  6#include <linux/cpuset.h>
  7#include <linux/cpumask.h>
  8#include <linux/delay.h>
  9#include <linux/kernel.h>
 10#include <linux/init.h>
 11#include <linux/sched.h>
 12#include <linux/security.h>
 13#include <linux/types.h>
 14#include <asm/uaccess.h>
 15
 16/*
 17 * CPU mask used to set process affinity for MT VPEs/TCs with FPUs
 18 */
 19cpumask_t mt_fpu_cpumask;
 20
 21static int fpaff_threshold = -1;
 22unsigned long mt_fpemul_threshold;
 23
 24/*
 25 * Replacement functions for the sys_sched_setaffinity() and
 26 * sys_sched_getaffinity() system calls, so that we can integrate
 27 * FPU affinity with the user's requested processor affinity.
 28 * This code is 98% identical with the sys_sched_setaffinity()
 29 * and sys_sched_getaffinity() system calls, and should be
 30 * updated when kernel/sched.c changes.
 31 */
 32
 33/*
 34 * find_process_by_pid - find a process with a matching PID value.
 35 * used in sys_sched_set/getaffinity() in kernel/sched.c, so
 36 * cloned here.
 37 */
 38static inline struct task_struct *find_process_by_pid(pid_t pid)
 39{
 40	return pid ? find_task_by_vpid(pid) : current;
 41}
 42
 43/*
 44 * check the target process has a UID that matches the current process's
 45 */
 46static bool check_same_owner(struct task_struct *p)
 47{
 48	const struct cred *cred = current_cred(), *pcred;
 49	bool match;
 50
 51	rcu_read_lock();
 52	pcred = __task_cred(p);
 53	match = (cred->euid == pcred->euid ||
 54		 cred->euid == pcred->uid);
 55	rcu_read_unlock();
 56	return match;
 57}
 58
 59/*
 60 * mipsmt_sys_sched_setaffinity - set the cpu affinity of a process
 61 */
 62asmlinkage long mipsmt_sys_sched_setaffinity(pid_t pid, unsigned int len,
 63				      unsigned long __user *user_mask_ptr)
 64{
 65	cpumask_var_t cpus_allowed, new_mask, effective_mask;
 66	struct thread_info *ti;
 67	struct task_struct *p;
 68	int retval;
 69
 70	if (len < sizeof(new_mask))
 71		return -EINVAL;
 72
 73	if (copy_from_user(&new_mask, user_mask_ptr, sizeof(new_mask)))
 74		return -EFAULT;
 75
 76	get_online_cpus();
 77	rcu_read_lock();
 78
 79	p = find_process_by_pid(pid);
 80	if (!p) {
 81		rcu_read_unlock();
 82		put_online_cpus();
 83		return -ESRCH;
 84	}
 85
 86	/* Prevent p going away */
 87	get_task_struct(p);
 88	rcu_read_unlock();
 89
 90	if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
 91		retval = -ENOMEM;
 92		goto out_put_task;
 93	}
 94	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL)) {
 95		retval = -ENOMEM;
 96		goto out_free_cpus_allowed;
 97	}
 98	if (!alloc_cpumask_var(&effective_mask, GFP_KERNEL)) {
 99		retval = -ENOMEM;
100		goto out_free_new_mask;
101	}
102	retval = -EPERM;
103	if (!check_same_owner(p) && !capable(CAP_SYS_NICE))
104		goto out_unlock;
105
106	retval = security_task_setscheduler(p, 0, NULL);
107	if (retval)
108		goto out_unlock;
109
110	/* Record new user-specified CPU set for future reference */
111	cpumask_copy(&p->thread.user_cpus_allowed, new_mask);
112
113 again:
114	/* Compute new global allowed CPU set if necessary */
115	ti = task_thread_info(p);
116	if (test_ti_thread_flag(ti, TIF_FPUBOUND) &&
117	    cpus_intersects(*new_mask, mt_fpu_cpumask)) {
118		cpus_and(*effective_mask, *new_mask, mt_fpu_cpumask);
119		retval = set_cpus_allowed_ptr(p, effective_mask);
120	} else {
121		cpumask_copy(effective_mask, new_mask);
122		clear_ti_thread_flag(ti, TIF_FPUBOUND);
123		retval = set_cpus_allowed_ptr(p, new_mask);
124	}
125
126	if (!retval) {
127		cpuset_cpus_allowed(p, cpus_allowed);
128		if (!cpumask_subset(effective_mask, cpus_allowed)) {
129			/*
130			 * We must have raced with a concurrent cpuset
131			 * update. Just reset the cpus_allowed to the
132			 * cpuset's cpus_allowed
133			 */
134			cpumask_copy(new_mask, cpus_allowed);
135			goto again;
136		}
137	}
138out_unlock:
139	free_cpumask_var(effective_mask);
140out_free_new_mask:
141	free_cpumask_var(new_mask);
142out_free_cpus_allowed:
143	free_cpumask_var(cpus_allowed);
144out_put_task:
145	put_task_struct(p);
146	put_online_cpus();
147	return retval;
148}
149
150/*
151 * mipsmt_sys_sched_getaffinity - get the cpu affinity of a process
152 */
153asmlinkage long mipsmt_sys_sched_getaffinity(pid_t pid, unsigned int len,
154				      unsigned long __user *user_mask_ptr)
155{
156	unsigned int real_len;
157	cpumask_t mask;
158	int retval;
159	struct task_struct *p;
160
161	real_len = sizeof(mask);
162	if (len < real_len)
163		return -EINVAL;
164
165	get_online_cpus();
166	read_lock(&tasklist_lock);
167
168	retval = -ESRCH;
169	p = find_process_by_pid(pid);
170	if (!p)
171		goto out_unlock;
172	retval = security_task_getscheduler(p);
173	if (retval)
174		goto out_unlock;
175
176	cpus_and(mask, p->thread.user_cpus_allowed, cpu_possible_map);
177
178out_unlock:
179	read_unlock(&tasklist_lock);
180	put_online_cpus();
181	if (retval)
182		return retval;
183	if (copy_to_user(user_mask_ptr, &mask, real_len))
184		return -EFAULT;
185	return real_len;
186}
187
188
189static int __init fpaff_thresh(char *str)
190{
191	get_option(&str, &fpaff_threshold);
192	return 1;
193}
194__setup("fpaff=", fpaff_thresh);
195
196/*
197 * FPU Use Factor empirically derived from experiments on 34K
198 */
199#define FPUSEFACTOR 2000
200
201static __init int mt_fp_affinity_init(void)
202{
203	if (fpaff_threshold >= 0) {
204		mt_fpemul_threshold = fpaff_threshold;
205	} else {
206		mt_fpemul_threshold =
207			(FPUSEFACTOR * (loops_per_jiffy/(500000/HZ))) / HZ;
208	}
209	printk(KERN_DEBUG "FPU Affinity set after %ld emulations\n",
210	       mt_fpemul_threshold);
211
212	return 0;
213}
214arch_initcall(mt_fp_affinity_init);