diff options
Diffstat (limited to 'kernel/cpuset.c')
| -rw-r--r-- | kernel/cpuset.c | 1564 |
1 files changed, 1564 insertions, 0 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c new file mode 100644 index 00000000000..69792bbe228 --- /dev/null +++ b/kernel/cpuset.c @@ -0,0 +1,1564 @@ +/* + * kernel/cpuset.c + * + * Processor and Memory placement constraints for sets of tasks. + * + * Copyright (C) 2003 BULL SA. + * Copyright (C) 2004 Silicon Graphics, Inc. + * + * Portions derived from Patrick Mochel's sysfs code. + * sysfs is Copyright (c) 2001-3 Patrick Mochel + * Portions Copyright (c) 2004 Silicon Graphics, Inc. + * + * 2003-10-10 Written by Simon Derr <simon.derr@bull.net> + * 2003-10-22 Updates by Stephen Hemminger. + * 2004 May-July Rework by Paul Jackson <pj@sgi.com> + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file COPYING in the main directory of the Linux + * distribution for more details. + */ + +#include <linux/config.h> +#include <linux/cpu.h> +#include <linux/cpumask.h> +#include <linux/cpuset.h> +#include <linux/err.h> +#include <linux/errno.h> +#include <linux/file.h> +#include <linux/fs.h> +#include <linux/init.h> +#include <linux/interrupt.h> +#include <linux/kernel.h> +#include <linux/kmod.h> +#include <linux/list.h> +#include <linux/mm.h> +#include <linux/module.h> +#include <linux/mount.h> +#include <linux/namei.h> +#include <linux/pagemap.h> +#include <linux/proc_fs.h> +#include <linux/sched.h> +#include <linux/seq_file.h> +#include <linux/slab.h> +#include <linux/smp_lock.h> +#include <linux/spinlock.h> +#include <linux/stat.h> +#include <linux/string.h> +#include <linux/time.h> +#include <linux/backing-dev.h> +#include <linux/sort.h> + +#include <asm/uaccess.h> +#include <asm/atomic.h> +#include <asm/semaphore.h> + +#define CPUSET_SUPER_MAGIC 0x27e0eb + +struct cpuset { + unsigned long flags; /* "unsigned long" so bitops work */ + cpumask_t cpus_allowed; /* CPUs allowed to tasks in cpuset */ + nodemask_t mems_allowed; /* Memory Nodes allowed to tasks */ + + atomic_t count; /* count tasks using this cpuset */ + + /* + * We link our 'sibling' struct into our parents 'children'. + * Our children link their 'sibling' into our 'children'. + */ + struct list_head sibling; /* my parents children */ + struct list_head children; /* my children */ + + struct cpuset *parent; /* my parent */ + struct dentry *dentry; /* cpuset fs entry */ + + /* + * Copy of global cpuset_mems_generation as of the most + * recent time this cpuset changed its mems_allowed. + */ + int mems_generation; +}; + +/* bits in struct cpuset flags field */ +typedef enum { + CS_CPU_EXCLUSIVE, + CS_MEM_EXCLUSIVE, + CS_REMOVED, + CS_NOTIFY_ON_RELEASE +} cpuset_flagbits_t; + +/* convenient tests for these bits */ +static inline int is_cpu_exclusive(const struct cpuset *cs) +{ + return !!test_bit(CS_CPU_EXCLUSIVE, &cs->flags); +} + +static inline int is_mem_exclusive(const struct cpuset *cs) +{ + return !!test_bit(CS_MEM_EXCLUSIVE, &cs->flags); +} + +static inline int is_removed(const struct cpuset *cs) +{ + return !!test_bit(CS_REMOVED, &cs->flags); +} + +static inline int notify_on_release(const struct cpuset *cs) +{ + return !!test_bit(CS_NOTIFY_ON_RELEASE, &cs->flags); +} + +/* + * Increment this atomic integer everytime any cpuset changes its + * mems_allowed value. Users of cpusets can track this generation + * number, and avoid having to lock and reload mems_allowed unless + * the cpuset they're using changes generation. + * + * A single, global generation is needed because attach_task() could + * reattach a task to a different cpuset, which must not have its + * generation numbers aliased with those of that tasks previous cpuset. + * + * Generations are needed for mems_allowed because one task cannot + * modify anothers memory placement. So we must enable every task, + * on every visit to __alloc_pages(), to efficiently check whether + * its current->cpuset->mems_allowed has changed, requiring an update + * of its current->mems_allowed. + */ +static atomic_t cpuset_mems_generation = ATOMIC_INIT(1); + +static struct cpuset top_cpuset = { + .flags = ((1 << CS_CPU_EXCLUSIVE) | (1 << CS_MEM_EXCLUSIVE)), + .cpus_allowed = CPU_MASK_ALL, + .mems_allowed = NODE_MASK_ALL, + .count = ATOMIC_INIT(0), + .sibling = LIST_HEAD_INIT(top_cpuset.sibling), + .children = LIST_HEAD_INIT(top_cpuset.children), + .parent = NULL, + .dentry = NULL, + .mems_generation = 0, +}; + +static struct vfsmount *cpuset_mount; +static struct super_block *cpuset_sb = NULL; + +/* + * cpuset_sem should be held by anyone who is depending on the children + * or sibling lists of any cpuset, or performing non-atomic operations + * on the flags or *_allowed values of a cpuset, such as raising the + * CS_REMOVED flag bit iff it is not already raised, or reading and + * conditionally modifying the *_allowed values. One kernel global + * cpuset semaphore should be sufficient - these things don't change + * that much. + * + * The code that modifies cpusets holds cpuset_sem across the entire + * operation, from cpuset_common_file_write() down, single threading + * all cpuset modifications (except for counter manipulations from + * fork and exit) across the system. This presumes that cpuset + * modifications are rare - better kept simple and safe, even if slow. + * + * The code that reads cpusets, such as in cpuset_common_file_read() + * and below, only holds cpuset_sem across small pieces of code, such + * as when reading out possibly multi-word cpumasks and nodemasks, as + * the risks are less, and the desire for performance a little greater. + * The proc_cpuset_show() routine needs to hold cpuset_sem to insure + * that no cs->dentry is NULL, as it walks up the cpuset tree to root. + * + * The hooks from fork and exit, cpuset_fork() and cpuset_exit(), don't + * (usually) grab cpuset_sem. These are the two most performance + * critical pieces of code here. The exception occurs on exit(), + * if the last task using a cpuset exits, and the cpuset was marked + * notify_on_release. In that case, the cpuset_sem is taken, the + * path to the released cpuset calculated, and a usermode call made + * to /sbin/cpuset_release_agent with the name of the cpuset (path + * relative to the root of cpuset file system) as the argument. + * + * A cpuset can only be deleted if both its 'count' of using tasks is + * zero, and its list of 'children' cpusets is empty. Since all tasks + * in the system use _some_ cpuset, and since there is always at least + * one task in the system (init, pid == 1), therefore, top_cpuset + * always has either children cpusets and/or using tasks. So no need + * for any special hack to ensure that top_cpuset cannot be deleted. + */ + +static DECLARE_MUTEX(cpuset_sem); + +/* + * A couple of forward declarations required, due to cyclic reference loop: + * cpuset_mkdir -> cpuset_create -> cpuset_populate_dir -> cpuset_add_file + * -> cpuset_create_file -> cpuset_dir_inode_operations -> cpuset_mkdir. + */ + +static int cpuset_mkdir(struct inode *dir, struct dentry *dentry, int mode); +static int cpuset_rmdir(struct inode *unused_dir, struct dentry *dentry); + +static struct backing_dev_info cpuset_backing_dev_info = { + .ra_pages = 0, /* No readahead */ + .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK, +}; + +static struct inode *cpuset_new_inode(mode_t mode) +{ + struct inode *inode = new_inode(cpuset_sb); + + if (inode) { + inode->i_mode = mode; + inode->i_uid = current->fsuid; + inode->i_gid = current->fsgid; + inode->i_blksize = PAGE_CACHE_SIZE; + inode->i_blocks = 0; + inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; + inode->i_mapping->backing_dev_info = &cpuset_backing_dev_info; + } + return inode; +} + +static void cpuset_diput(struct dentry *dentry, struct inode *inode) +{ + /* is dentry a directory ? if so, kfree() associated cpuset */ + if (S_ISDIR(inode->i_mode)) { + struct cpuset *cs = dentry->d_fsdata; + BUG_ON(!(is_removed(cs))); + kfree(cs); + } + iput(inode); +} + +static struct dentry_operations cpuset_dops = { + .d_iput = cpuset_diput, +}; + +static struct dentry *cpuset_get_dentry(struct dentry *parent, const char *name) +{ + struct qstr qstr; + struct dentry *d; + + qstr.name = name; + qstr.len = strlen(name); + qstr.hash = full_name_hash(name, qstr.len); + d = lookup_hash(&qstr, parent); + if (!IS_ERR(d)) + d->d_op = &cpuset_dops; + return d; +} + +static void remove_dir(struct dentry *d) +{ + struct dentry *parent = dget(d->d_parent); + + d_delete(d); + simple_rmdir(parent->d_inode, d); + dput(parent); +} + +/* + * NOTE : the dentry must have been dget()'ed + */ +static void cpuset_d_remove_dir(struct dentry *dentry) +{ + struct list_head *node; + + spin_lock(&dcache_lock); + node = dentry->d_subdirs.next; + while (node != &dentry->d_subdirs) { + struct dentry *d = list_entry(node, struct dentry, d_child); + list_del_init(node); + if (d->d_inode) { + d = dget_locked(d); + spin_unlock(&dcache_lock); + d_delete(d); + simple_unlink(dentry->d_inode, d); + dput(d); + spin_lock(&dcache_lock); + } + node = dentry->d_subdirs.next; + } + list_del_init(&dentry->d_child); + spin_unlock(&dcache_lock); + remove_dir(dentry); +} + +static struct super_operations cpuset_ops = { + .statfs = simple_statfs, + .drop_inode = generic_delete_inode, +}; + +static int cpuset_fill_super(struct super_block *sb, void *unused_data, + int unused_silent) +{ + struct inode *inode; + struct dentry *root; + + sb->s_blocksize = PAGE_CACHE_SIZE; + sb->s_blocksize_bits = PAGE_CACHE_SHIFT; + sb->s_magic = CPUSET_SUPER_MAGIC; + sb->s_op = &cpuset_ops; + cpuset_sb = sb; + + inode = cpuset_new_inode(S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR); + if (inode) { + inode->i_op = &simple_dir_inode_operations; + inode->i_fop = &simple_dir_operations; + /* directories start off with i_nlink == 2 (for "." entry) */ + inode->i_nlink++; + } else { + return -ENOMEM; + } + + root = d_alloc_root(inode); + if (!root) { + iput(inode); + return -ENOMEM; + } + sb->s_root = root; + return 0; +} + +static struct super_block *cpuset_get_sb(struct file_system_type *fs_type, + int flags, const char *unused_dev_name, + void *data) +{ + return get_sb_single(fs_type, flags, data, cpuset_fill_super); +} + +static struct file_system_type cpuset_fs_type = { + .name = "cpuset", + .get_sb = cpuset_get_sb, + .kill_sb = kill_litter_super, +}; + +/* struct cftype: + * + * The files in the cpuset filesystem mostly have a very simple read/write + * handling, some common function will take care of it. Nevertheless some cases + * (read tasks) are special and therefore I define this structure for every + * kind of file. + * + * + * When reading/writing to a file: + * - the cpuset to use in file->f_dentry->d_parent->d_fsdata + * - the 'cftype' of the file is file->f_dentry->d_fsdata + */ + +struct cftype { + char *name; + int private; + int (*open) (struct inode *inode, struct file *file); + ssize_t (*read) (struct file *file, char __user *buf, size_t nbytes, + loff_t *ppos); + int (*write) (struct file *file, const char __user *buf, size_t nbytes, + loff_t *ppos); + int (*release) (struct inode *inode, struct file *file); +}; + +static inline struct cpuset *__d_cs(struct dentry *dentry) +{ + return dentry->d_fsdata; +} + +static inline struct cftype *__d_cft(struct dentry *dentry) +{ + return dentry->d_fsdata; +} + +/* + * Call with cpuset_sem held. Writes path of cpuset into buf. + * Returns 0 on success, -errno on error. + */ + +static int cpuset_path(const struct cpuset *cs, char *buf, int buflen) +{ + char *start; + + start = buf + buflen; + + *--start = '\0'; + for (;;) { + int len = cs->dentry->d_name.len; + if ((start -= len) < buf) + return -ENAMETOOLONG; + memcpy(start, cs->dentry->d_name.name, len); + cs = cs->parent; + if (!cs) + break; + if (!cs->parent) + continue; + if (--start < buf) + return -ENAMETOOLONG; + *start = '/'; + } + memmove(buf, start, buf + buflen - start); + return 0; +} + +/* + * Notify userspace when a cpuset is released, by running + * /sbin/cpuset_release_agent with the name of the cpuset (path + * relative to the root of cpuset file system) as the argument. + * + * Most likely, this user command will try to rmdir this cpuset. + * + * This races with the possibility that some other task will be + * attached to this cpuset before it is removed, or that some other + * user task will 'mkdir' a child cpuset of this cpuset. That's ok. + * The presumed 'rmdir' will fail quietly if this cpuset is no longer + * unused, and this cpuset will be reprieved from its death sentence, + * to continue to serve a useful existence. Next time it's released, + * we will get notified again, if it still has 'notify_on_release' set. + * + * Note final arg to call_usermodehelper() is 0 - that means + * don't wait. Since we are holding the global cpuset_sem here, + * and we are asking another thread (started from keventd) to rmdir a + * cpuset, we can't wait - or we'd deadlock with the removing thread + * on cpuset_sem. + */ + +static int cpuset_release_agent(char *cpuset_str) +{ + char *argv[3], *envp[3]; + int i; + + i = 0; + argv[i++] = "/sbin/cpuset_release_agent"; + argv[i++] = cpuset_str; + argv[i] = NULL; + + i = 0; + /* minimal command environment */ + envp[i++] = "HOME=/"; + envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; + envp[i] = NULL; + + return call_usermodehelper(argv[0], argv, envp, 0); +} + +/* + * Either cs->count of using tasks transitioned to zero, or the + * cs->children list of child cpusets just became empty. If this + * cs is notify_on_release() and now both the user count is zero and + * the list of children is empty, send notice to user land. + */ + +static void check_for_release(struct cpuset *cs) +{ + if (notify_on_release(cs) && atomic_read(&cs->count) == 0 && + list_empty(&cs->children)) { + char *buf; + + buf = kmalloc(PAGE_SIZE, GFP_KERNEL); + if (!buf) + return; + if (cpuset_path(cs, buf, PAGE_SIZE) < 0) + goto out; + cpuset_release_agent(buf); +out: + kfree(buf); + } +} + +/* + * Return in *pmask the portion of a cpusets's cpus_allowed that + * are online. If none are online, walk up the cpuset hierarchy + * until we find one that does have some online cpus. If we get + * all the way to the top and still haven't found any online cpus, + * return cpu_online_map. Or if passed a NULL cs from an exit'ing + * task, return cpu_online_map. + * + * One way or another, we guarantee to return some non-empty subset + * of cpu_online_map. + * + * Call with cpuset_sem held. + */ + +static void guarantee_online_cpus(const struct cpuset *cs, cpumask_t *pmask) +{ + while (cs && !cpus_intersects(cs->cpus_allowed, cpu_online_map)) + cs = cs->parent; + if (cs) + cpus_and(*pmask, cs->cpus_allowed, cpu_online_map); + else + *pmask = cpu_online_map; + BUG_ON(!cpus_intersects(*pmask, cpu_online_map)); +} + +/* + * Return in *pmask the portion of a cpusets's mems_allowed that + * are online. If none are online, walk up the cpuset hierarchy + * until we find one that does have some online mems. If we get + * all the way to the top and still haven't found any online mems, + * return node_online_map. + * + * One way or another, we guarantee to return some non-empty subset + * of node_online_map. + * + * Call with cpuset_sem held. + */ + +static void guarantee_online_mems(const struct cpuset *cs, nodemask_t *pmask) +{ + while (cs && !nodes_intersects(cs->mems_allowed, node_online_map)) + cs = cs->parent; + if (cs) + nodes_and(*pmask, cs->mems_allowed, node_online_map); + else + *pmask = node_online_map; + BUG_ON(!nodes_intersects(*pmask, node_online_map)); +} + +/* + * Refresh current tasks mems_allowed and mems_generation from + * current tasks cpuset. Call with cpuset_sem held. + * + * Be sure to call refresh_mems() on any cpuset operation which + * (1) holds cpuset_sem, and (2) might possibly alloc memory. + * Call after obtaining cpuset_sem lock, before any possible + * allocation. Otherwise one risks trying to allocate memory + * while the task cpuset_mems_generation is not the same as + * the mems_generation in its cpuset, which would deadlock on + * cpuset_sem in cpuset_update_current_mems_allowed(). + * + * Since we hold cpuset_sem, once refresh_mems() is called, the + * test (current->cpuset_mems_generation != cs->mems_generation) + * in cpuset_update_current_mems_allowed() will remain false, + * until we drop cpuset_sem. Anyone else who would change our + * cpusets mems_generation needs to lock cpuset_sem first. + */ + +static void refresh_mems(void) +{ + struct cpuset *cs = current->cpuset; + + if (current->cpuset_mems_generation != cs->mems_generation) { + guarantee_online_mems(cs, ¤t->mems_allowed); + current->cpuset_mems_generation = cs->mems_generation; + } +} + +/* + * is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q? + * + * One cpuset is a subset of another if all its allowed CPUs and + * Memory Nodes are a subset of the other, and its exclusive flags + * are only set if the other's are set. + */ + +static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q) +{ + return cpus_subset(p->cpus_allowed, q->cpus_allowed) && + nodes_subset(p->mems_allowed, q->mems_allowed) && + is_cpu_exclusive(p) <= is_cpu_exclusive(q) && + is_mem_exclusive(p) <= is_mem_exclusive(q); +} + +/* + * validate_change() - Used to validate that any proposed cpuset change + * follows the structural rules for cpusets. + * + * If we replaced the flag and mask values of the current cpuset + * (cur) with those values in the trial cpuset (trial), would + * our various subset and exclusive rules still be valid? Presumes + * cpuset_sem held. + * + * 'cur' is the address of an actual, in-use cpuset. Operations + * such as list traversal that depend on the actual address of the + * cpuset in the list must use cur below, not trial. + * + * 'trial' is the address of bulk structure copy of cur, with + * perhaps one or more of the fields cpus_allowed, mems_allowed, + * or flags changed to new, trial values. + * + * Return 0 if valid, -errno if not. + */ + +static int validate_change(const struct cpuset *cur, const struct cpuset *trial) +{ + struct cpuset *c, *par; + + /* Each of our child cpusets must be a subset of us */ + list_for_each_entry(c, &cur->children, sibling) { + if (!is_cpuset_subset(c, trial)) + return -EBUSY; + } + + /* Remaining checks don't apply to root cpuset */ + if ((par = cur->parent) == NULL) + return 0; + + /* We must be a subset of our parent cpuset */ + if (!is_cpuset_subset(trial, par)) + return -EACCES; + + /* If either I or some sibling (!= me) is exclusive, we can't overlap */ + list_for_each_entry(c, &par->children, sibling) { + if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) && + c != cur && + cpus_intersects(trial->cpus_allowed, c->cpus_allowed)) + return -EINVAL; + if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) && + c != cur && + nodes_intersects(trial->mems_allowed, c->mems_allowed)) + return -EINVAL; + } + + return 0; +} + +static int update_cpumask(struct cpuset *cs, char *buf) +{ + struct cpuset trialcs; + int retval; + + trialcs = *cs; + retval = cpulist_parse(buf, trialcs.cpus_allowed); + if (retval < 0) + return retval; + cpus_and(trialcs.cpus_allowed, trialcs.cpus_allowed, cpu_online_map); + if (cpus_empty(trialcs.cpus_allowed)) + return -ENOSPC; + retval = validate_change(cs, &trialcs); + if (retval == 0) + cs->cpus_allowed = trialcs.cpus_allowed; + return retval; +} + +static int update_nodemask(struct cpuset *cs, char *buf) +{ + struct cpuset trialcs; + int retval; + + trialcs = *cs; + retval = nodelist_parse(buf, trialcs.mems_allowed); + if (retval < 0) + return retval; + nodes_and(trialcs.mems_allowed, trialcs.mems_allowed, node_online_map); + if (nodes_empty(trialcs.mems_allowed)) + return -ENOSPC; + retval = validate_change(cs, &trialcs); + if (retval == 0) { + cs->mems_allowed = trialcs.mems_allowed; + atomic_inc(&cpuset_mems_generation); + cs->mems_generation = atomic_read(&cpuset_mems_generation); + } + return retval; +} + +/* + * update_flag - read a 0 or a 1 in a file and update associated flag + * bit: the bit to update (CS_CPU_EXCLUSIVE, CS_MEM_EXCLUSIVE, + * CS_NOTIFY_ON_RELEASE) + * cs: the cpuset to update + * buf: the buffer where we read the 0 or 1 + */ + +static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs, char *buf) +{ + int turning_on; + struct cpuset trialcs; + int err; + + turning_on = (simple_strtoul(buf, NULL, 10) != 0); + + trialcs = *cs; + if (turning_on) + set_bit(bit, &trialcs.flags); + else + clear_bit(bit, &trialcs.flags); + + err = validate_change(cs, &trialcs); + if (err == 0) { + if (turning_on) + set_bit(bit, &cs->flags); + else + clear_bit(bit, &cs->flags); + } + return err; +} + +static int attach_task(struct cpuset *cs, char *buf) +{ + pid_t pid; + struct task_struct *tsk; + struct cpuset *oldcs; + cpumask_t cpus; + + if (sscanf(buf, "%d", &pid) != 1) + return -EIO; + if (cpus_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)) + return -ENOSPC; + + if (pid) { + read_lock(&tasklist_lock); + + tsk = find_task_by_pid(pid); + if (!tsk) { + read_unlock(&tasklist_lock); + return -ESRCH; + } + + get_task_struct(tsk); + read_unlock(&tasklist_lock); + + if ((current->euid) && (current->euid != tsk->uid) + && (current->euid != tsk->suid)) { + put_task_struct(tsk); + return -EACCES; + } + } else { + tsk = current; + get_task_struct(tsk); + } + + task_lock(tsk); + oldcs = tsk->cpuset; + if (!oldcs) { + task_unlock(tsk); + put_task_struct(tsk); + return -ESRCH; + } + atomic_inc(&cs->count); + tsk->cpuset = cs; + task_unlock(tsk); + + guarantee_online_cpus(cs, &cpus); + set_cpus_allowed(tsk, cpus); + + put_task_struct(tsk); + if (atomic_dec_and_test(&oldcs->count)) + check_for_release(oldcs); + return 0; +} + +/* The various types of files and directories in a cpuset file system */ + +typedef enum { + FILE_ROOT, + FILE_DIR, + FILE_CPULIST, + FILE_MEMLIST, + FILE_CPU_EXCLUSIVE, + FILE_MEM_EXCLUSIVE, + FILE_NOTIFY_ON_RELEASE, + FILE_TASKLIST, +} cpuset_filetype_t; + +static ssize_t cpuset_common_file_write(struct file *file, const char __user *userbuf, + size_t nbytes, loff_t *unused_ppos) +{ + struct cpuset *cs = __d_cs(file->f_dentry->d_parent); + struct cftype *cft = __d_cft(file->f_dentry); + cpuset_filetype_t type = cft->private; + char *buffer; + int retval = 0; + + /* Crude upper limit on largest legitimate cpulist user might write. */ + if (nbytes > 100 + 6 * NR_CPUS) + return -E2BIG; + + /* +1 for nul-terminator */ + if ((buffer = kmalloc(nbytes + 1, GFP_KERNEL)) == 0) + return -ENOMEM; + + if (copy_from_user(buffer, userbuf, nbytes)) { + retval = -EFAULT; + goto out1; + } + buffer[nbytes] = 0; /* nul-terminate */ + + down(&cpuset_sem); + + if (is_removed(cs)) { + retval = -ENODEV; + goto out2; + } + + switch (type) { + case FILE_CPULIST: + retval = update_cpumask(cs, buffer); + break; + case FILE_MEMLIST: + retval = update_nodemask(cs, buffer); + break; + case FILE_CPU_EXCLUSIVE: + retval = update_flag(CS_CPU_EXCLUSIVE, cs, buffer); + break; + case FILE_MEM_EXCLUSIVE: + retval = update_flag(CS_MEM_EXCLUSIVE, cs, buffer); + break; + case FILE_NOTIFY_ON_RELEASE: + retval = update_flag(CS_NOTIFY_ON_RELEASE, cs, buffer); + break; + case FILE_TASKLIST: + retval = attach_task(cs, buffer); + break; + default: + retval = -EINVAL; + goto out2; + } + + if (retval == 0) + retval = nbytes; +out2: + up(&cpuset_sem); +out1: + kfree(buffer); + return retval; +} + +static ssize_t cpuset_file_write(struct file *file, const char __user *buf, + size_t nbytes, loff_t *ppos) +{ + ssize_t retval = 0; + struct cftype *cft = __d_cft(file->f_dentry); + if (!cft) + return -ENODEV; + + /* special function ? */ + if (cft->write) + retval = cft->write(file, buf, nbytes, ppos); + else + retval = cpuset_common_file_write(file, buf, nbytes, ppos); + + return retval; +} + +/* + * These ascii lists should be read in a single call, by using a user + * buffer large enough to hold the entire map. If read in smaller + * chunks, there is no guarantee of atomicity. Since the display format + * used, list of ranges of sequential numbers, is variable length, + * and since these maps can change value dynamically, one could read + * gibberish by doing partial reads while a list was changing. + * A single large read to a buffer that crosses a page boundary is + * ok, because the result being copied to user land is not recomputed + * across a page fault. + */ + +static int cpuset_sprintf_cpulist(char *page, struct cpuset *cs) +{ + cpumask_t mask; + + down(&cpuset_sem); + mask = cs->cpus_allowed; + up(&cpuset_sem); + + return cpulist_scnprintf(page, PAGE_SIZE, mask); +} + +static int cpuset_sprintf_memlist(char *page, struct cpuset *cs) +{ + nodemask_t mask; + + down(&cpuset_sem); + mask = cs->mems_allowed; + up(&cpuset_sem); + + return nodelist_scnprintf(page, PAGE_SIZE, mask); +} + +static ssize_t cpuset_common_file_read(struct file *file, char __user *buf, + size_t nbytes, loff_t *ppos) +{ + struct cftype *cft = __d_cft(file->f_dentry); + struct cpuset *cs = __d_cs(file->f_dentry->d_parent); + cpuset_filetype_t type = cft->private; + char *page; + ssize_t retval = 0; + char *s; + char *start; + size_t n; + + if (!(page = (char *)__get_free_page(GFP_KERNEL))) + return -ENOMEM; + + s = page; + + switch (type) { + case FILE_CPULIST: + s += cpuset_sprintf_cpulist(s, cs); + break; + case FILE_MEMLIST: + s += cpuset_sprintf_memlist(s, cs); + break; + case FILE_CPU_EXCLUSIVE: + *s++ = is_cpu_exclusive(cs) ? '1' : '0'; + break; + case FILE_MEM_EXCLUSIVE: + *s++ = is_mem_exclusive(cs) ? '1' : '0'; + break; + case FILE_NOTIFY_ON_RELEASE: + *s++ = notify_on_release(cs) ? '1' : '0'; + break; + default: + retval = -EINVAL; + goto out; + } + *s++ = '\n'; + *s = '\0'; + + start = page + *ppos; + n = s - start; + retval = n - copy_to_user(buf, start, min(n, nbytes)); + *ppos += retval; +out: + free_page((unsigned long)page); + return retval; +} + +static ssize_t cpuset_file_read(struct file *file, char __user *buf, size_t nbytes, + loff_t *ppos) +{ + ssize_t retval = 0; + struct cftype *cft = __d_cft(file->f_dentry); + if (!cft) + return -ENODEV; + + /* special function ? */ + if (cft->read) + retval = cft->read(file, buf, nbytes, ppos); + else + retval = cpuset_common_file_read(file, buf, nbytes, ppos); + + return retval; +} + +static int cpuset_file_open(struct inode *inode, struct file *file) +{ + int err; + struct cftype *cft; + + err = generic_file_open(inode, file); + if (err) + return err; + + cft = __d_cft(file->f_dentry); + if (!cft) + return -ENODEV; + if (cft->open) + err = cft->open(inode, file); + else + err = 0; + + return err; +} + +static int cpuset_file_release(struct inode *inode, struct file *file) +{ + struct cftype *cft = __d_cft(file->f_dentry); + if (cft->release) + return cft->release(inode, file); + return 0; +} + +static struct file_operations cpuset_file_operations = { + .read = cpuset_file_read, + .write = cpuset_file_write, + .llseek = generic_file_llseek, + .open = cpuset_file_open, + .release = cpuset_file_release, +}; + +static struct inode_operations cpuset_dir_inode_operations = { + .lookup = simple_lookup, + .mkdir = cpuset_mkdir, + .rmdir = cpuset_rmdir, +}; + +static int cpuset_create_file(struct dentry *dentry, int mode) +{ + struct inode *inode; + + if (!dentry) + return -ENOENT; + if (dentry->d_inode) + return -EEXIST; + + inode = cpuset_new_inode(mode); + if (!inode) + return -ENOMEM; + + if (S_ISDIR(mode)) { + inode->i_op = &cpuset_dir_inode_operations; + inode->i_fop = &simple_dir_operations; + + /* start off with i_nlink == 2 (for "." entry) */ + inode->i_nlink++; + } else if (S_ISREG(mode)) { + inode->i_size = 0; + inode->i_fop = &cpuset_file_operations; + } + + d_instantiate(dentry, inode); + dget(dentry); /* Extra count - pin the dentry in core */ + return 0; +} + +/* + * cpuset_create_dir - create a directory for an object. + * cs: the cpuset we create the directory for. + * It must have a valid ->parent field + * And we are going to fill its ->dentry field. + * name: The name to give to the cpuset directory. Will be copied. + * mode: mode to set on new directory. + */ + +static int cpuset_create_dir(struct cpuset *cs, const char *name, int mode) +{ + struct dentry *dentry = NULL; + struct dentry *parent; + int error = 0; + + parent = cs->parent->dentry; + dentry = cpuset_get_dentry(parent, name); + if (IS_ERR(dentry)) + return PTR_ERR(dentry); + error = cpuset_create_file(dentry, S_IFDIR | mode); + if (!error) { + dentry->d_fsdata = cs; + parent->d_inode->i_nlink++; + cs->dentry = dentry; + } + dput(dentry); + + return error; +} + +static int cpuset_add_file(struct dentry *dir, const struct cftype *cft) +{ + struct dentry *dentry; + int error; + + down(&dir->d_inode->i_sem); + dentry = cpuset_get_dentry(dir, cft->name); + if (!IS_ERR(dentry)) { + error = cpuset_create_file(dentry, 0644 | S_IFREG); + if (!error) + dentry->d_fsdata = (void *)cft; + dput(dentry); + } else + error = PTR_ERR(dentry); + up(&dir->d_inode->i_sem); + return error; +} + +/* + * Stuff for reading the 'tasks' file. + * + * Reading this file can return large amounts of data if a cpuset has + * *lots* of attached tasks. So it may need several calls to read(), + * but we cannot guarantee that the information we produce is correct + * unless we produce it entirely atomically. + * + * Upon tasks file open(), a struct ctr_struct is allocated, that + * will have a pointer to an array (also allocated here). The struct + * ctr_struct * is stored in file->private_data. Its resources will + * be freed by release() when the file is closed. The array is used + * to sprintf the PIDs and then used by read(). + */ + +/* cpusets_tasks_read array */ + +struct ctr_struct { + char *buf; + int bufsz; +}; + +/* + * Load into 'pidarray' up to 'npids' of the tasks using cpuset 'cs'. + * Return actual number of pids loaded. + */ +static inline int pid_array_load(pid_t *pidarray, int npids, struct cpuset *cs) +{ + int n = 0; + struct task_struct *g, *p; + + read_lock(&tasklist_lock); + + do_each_thread(g, p) { + if (p->cpuset == cs) { + pidarray[n++] = p->pid; + if (unlikely(n == npids)) + goto array_full; + } + } while_each_thread(g, p); + +array_full: + read_unlock(&tasklist_lock); + return n; +} + +static int cmppid(const void *a, const void *b) +{ + return *(pid_t *)a - *(pid_t *)b; +} + +/* + * Convert array 'a' of 'npids' pid_t's to a string of newline separated + * decimal pids in 'buf'. Don't write more than 'sz' chars, but return + * count 'cnt' of how many chars would be written if buf were large enough. + */ +static int pid_array_to_buf(char *buf, int sz, pid_t *a, int npids) +{ + int cnt = 0; + int i; + + for (i = 0; i < npids; i++) + cnt += snprintf(buf + cnt, max(sz - cnt, 0), "%d\n", a[i]); + return cnt; +} + +static int cpuset_tasks_open(struct inode *unused, struct file *file) +{ + struct cpuset *cs = __d_cs(file->f_dentry->d_parent); + struct ctr_struct *ctr; + pid_t *pidarray; + int npids; + char c; + + if (!(file->f_mode & FMODE_READ)) + return 0; + + ctr = kmalloc(sizeof(*ctr), GFP_KERNEL); + if (!ctr) + goto err0; + + /* + * If cpuset gets more users after we read count, we won't have + * enough space - tough. This race is indistinguishable to the + * caller from the case that the additional cpuset users didn't + * show up until sometime later on. + */ + npids = atomic_read(&cs->count); + pidarray = kmalloc(npids * sizeof(pid_t), GFP_KERNEL); + if (!pidarray) + goto err1; + + npids = pid_array_load(pidarray, npids, cs); + sort(pidarray, npids, sizeof(pid_t), cmppid, NULL); + + /* Call pid_array_to_buf() twice, first just to get bufsz */ + ctr->bufsz = pid_array_to_buf(&c, sizeof(c), pidarray, npids) + 1; + ctr->buf = kmalloc(ctr->bufsz, GFP_KERNEL); + if (!ctr->buf) + goto err2; + ctr->bufsz = pid_array_to_buf(ctr->buf, ctr->bufsz, pidarray, npids); + + kfree(pidarray); + file->private_data = ctr; + return 0; + +err2: + kfree(pidarray); +err1: + kfree(ctr); +err0: + return -ENOMEM; +} + +static ssize_t cpuset_tasks_read(struct file *file, char __user *buf, + size_t nbytes, loff_t *ppos) +{ + struct ctr_struct *ctr = file->private_data; + + if (*ppos + nbytes > ctr->bufsz) + nbytes = ctr->bufsz - *ppos; + if (copy_to_user(buf, ctr->buf + *ppos, nbytes)) + return -EFAULT; + *ppos += nbytes; + return nbytes; +} + +static int cpuset_tasks_release(struct inode *unused_inode, struct file *file) +{ + struct ctr_struct *ctr; + + if (file->f_mode & FMODE_READ) { + ctr = file->private_data; + kfree(ctr->buf); + kfree(ctr); + } + return 0; +} + +/* + * for the common functions, 'private' gives the type of file + */ + +static struct cftype cft_tasks = { + .name = "tasks", + .open = cpuset_tasks_open, + .read = cpuset_tasks_read, + .release = cpuset_tasks_release, + .private = FILE_TASKLIST, +}; + +static struct cftype cft_cpus = { + .name = "cpus", + .private = FILE_CPULIST, +}; + +static struct cftype cft_mems = { + .name = "mems", + .private = FILE_MEMLIST, +}; + +static struct cftype cft_cpu_exclusive = { + .name = "cpu_exclusive", + .private = FILE_CPU_EXCLUSIVE, +}; + +static struct cftype cft_mem_exclusive = { + .name = "mem_exclusive", + .private = FILE_MEM_EXCLUSIVE, +}; + +static struct cftype cft_notify_on_release = { + .name = "notify_on_release", + .private = FILE_NOTIFY_ON_RELEASE, +}; + +static int cpuset_populate_dir(struct dentry *cs_dentry) +{ + int err; + + if ((err = cpuset_add_file(cs_dentry, &cft_cpus)) < 0) + return err; + if ((err = cpuset_add_file(cs_dentry, &cft_mems)) < 0) + return err; + if ((err = cpuset_add_file(cs_dentry, &cft_cpu_exclusive)) < 0) + return err; + if ((err = cpuset_add_file(cs_dentry, &cft_mem_exclusive)) < 0) + return err; + if ((err = cpuset_add_file(cs_dentry, &cft_notify_on_release)) < 0) + return err; + if ((err = cpuset_add_file(cs_dentry, &cft_tasks)) < 0) + return err; + return 0; +} + +/* + * cpuset_create - create a cpuset + * parent: cpuset that will be parent of the new cpuset. + * name: name of the new cpuset. Will be strcpy'ed. + * mode: mode to set on new inode + * + * Must be called with the semaphore on the parent inode held + */ + +static long cpuset_create(struct cpuset *parent, const char *name, int mode) +{ + struct cpuset *cs; + int err; + + cs = kmalloc(sizeof(*cs), GFP_KERNEL); + if (!cs) + return -ENOMEM; + + down(&cpuset_sem); + refresh_mems(); + cs->flags = 0; + if (notify_on_release(parent)) + set_bit(CS_NOTIFY_ON_RELEASE, &cs->flags); + cs->cpus_allowed = CPU_MASK_NONE; + cs->mems_allowed = NODE_MASK_NONE; + atomic_set(&cs->count, 0); + INIT_LIST_HEAD(&cs->sibling); + INIT_LIST_HEAD(&cs->children); + atomic_inc(&cpuset_mems_generation); + cs->mems_generation = atomic_read(&cpuset_mems_generation); + + cs->parent = parent; + + list_add(&cs->sibling, &cs->parent->children); + + err = cpuset_create_dir(cs, name, mode); + if (err < 0) + goto err; + + /* + * Release cpuset_sem before cpuset_populate_dir() because it + * will down() this new directory's i_sem and if we race with + * another mkdir, we might deadlock. + */ + up(&cpuset_sem); + + err = cpuset_populate_dir(cs->dentry); + /* If err < 0, we have a half-filled directory - oh well ;) */ + return 0; +err: + list_del(&cs->sibling); + up(&cpuset_sem); + kfree(cs); + return err; +} + +static int cpuset_mkdir(struct inode *dir, struct dentry *dentry, int mode) +{ + struct cpuset *c_parent = dentry->d_parent->d_fsdata; + + /* the vfs holds inode->i_sem already */ + return cpuset_create(c_parent, dentry->d_name.name, mode | S_IFDIR); +} + +static int cpuset_rmdir(struct inode *unused_dir, struct dentry *dentry) +{ + struct cpuset *cs = dentry->d_fsdata; + struct dentry *d; + struct cpuset *parent; + + /* the vfs holds both inode->i_sem already */ + + down(&cpuset_sem); + refresh_mems(); + if (atomic_read(&cs->count) > 0) { + up(&cpuset_sem); + return -EBUSY; + } + if (!list_empty(&cs->children)) { + up(&cpuset_sem); + return -EBUSY; + } + spin_lock(&cs->dentry->d_lock); + parent = cs->parent; + set_bit(CS_REMOVED, &cs->flags); + list_del(&cs->sibling); /* delete my sibling from parent->children */ + if (list_empty(&parent->children)) + check_for_release(parent); + d = dget(cs->dentry); + cs->dentry = NULL; + spin_unlock(&d->d_lock); + cpuset_d_remove_dir(d); + dput(d); + up(&cpuset_sem); + return 0; +} + +/** + * cpuset_init - initialize cpusets at system boot + * + * Description: Initialize top_cpuset and the cpuset internal file system, + **/ + +int __init cpuset_init(void) +{ + struct dentry *root; + int err; + + top_cpuset.cpus_allowed = CPU_MASK_ALL; + top_cpuset.mems_allowed = NODE_MASK_ALL; + + atomic_inc(&cpuset_mems_generation); + top_cpuset.mems_generation = atomic_read(&cpuset_mems_generation); + + init_task.cpuset = &top_cpuset; + + err = register_filesystem(&cpuset_fs_type); + if (err < 0) + goto out; + cpuset_mount = kern_mount(&cpuset_fs_type); + if (IS_ERR(cpuset_mount)) { + printk(KERN_ERR "cpuset: could not mount!\n"); + err = PTR_ERR(cpuset_mount); + cpuset_mount = NULL; + goto out; + } + root = cpuset_mount->mnt_sb->s_root; + root->d_fsdata = &top_cpuset; + root->d_inode->i_nlink++; + top_cpuset.dentry = root; + root->d_inode->i_op = &cpuset_dir_inode_operations; + err = cpuset_populate_dir(root); +out: + return err; +} + +/** + * cpuset_init_smp - initialize cpus_allowed + * + * Description: Finish top cpuset after cpu, node maps are initialized + **/ + +void __init cpuset_init_smp(void) +{ + top_cpuset.cpus_allowed = cpu_online_map; + top_cpuset.mems_allowed = node_online_map; +} + +/** + * cpuset_fork - attach newly forked task to its parents cpuset. + * @p: pointer to task_struct of forking parent process. + * + * Description: By default, on fork, a task inherits its + * parents cpuset. The pointer to the shared cpuset is + * automatically copied in fork.c by dup_task_struct(). + * This cpuset_fork() routine need only increment the usage + * counter in that cpuset. + **/ + +void cpuset_fork(struct task_struct *tsk) +{ + atomic_inc(&tsk->cpuset->count); +} + +/** + * cpuset_exit - detach cpuset from exiting task + * @tsk: pointer to task_struct of exiting process + * + * Description: Detach cpuset from @tsk and release it. + * + **/ + +void cpuset_exit(struct task_struct *tsk) +{ + struct cpuset *cs; + + task_lock(tsk); + cs = tsk->cpuset; + tsk->cpuset = NULL; + task_unlock(tsk); + + if (atomic_dec_and_test(&cs->count)) { + down(&cpuset_sem); + check_for_release(cs); + up(&cpuset_sem); + } +} + +/** + * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset. + * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed. + * + * Description: Returns the cpumask_t cpus_allowed of the cpuset + * attached to the specified @tsk. Guaranteed to return some non-empty + * subset of cpu_online_map, even if this means going outside the + * tasks cpuset. + **/ + +const cpumask_t cpuset_cpus_allowed(const struct task_struct *tsk) +{ + cpumask_t mask; + + down(&cpuset_sem); + task_lock((struct task_struct *)tsk); + guarantee_online_cpus(tsk->cpuset, &mask); + task_unlock((struct task_struct *)tsk); + up(&cpuset_sem); + + return mask; +} + +void cpuset_init_current_mems_allowed(void) +{ + current->mems_allowed = NODE_MASK_ALL; +} + +/* + * If the current tasks cpusets mems_allowed changed behind our backs, + * update current->mems_allowed and mems_generation to the new value. + * Do not call this routine if in_interrupt(). + */ + +void cpuset_update_current_mems_allowed(void) +{ + struct cpuset *cs = current->cpuset; + + if (!cs) + return; /* task is exiting */ + if (current->cpuset_mems_generation != cs->mems_generation) { + down(&cpuset_sem); + refresh_mems(); + up(&cpuset_sem); + } +} + +void cpuset_restrict_to_mems_allowed(unsigned long *nodes) +{ + bitmap_and(nodes, nodes, nodes_addr(current->mems_allowed), + MAX_NUMNODES); +} + +/* + * Are any of the nodes on zonelist zl allowed in current->mems_allowed? + */ +int cpuset_zonelist_valid_mems_allowed(struct zonelist *zl) +{ + int i; + + for (i = 0; zl->zones[i]; i++) { + int nid = zl->zones[i]->zone_pgdat->node_id; + + if (node_isset(nid, current->mems_allowed)) + return 1; + } + return 0; +} + +/* + * Is 'current' valid, and is zone z allowed in current->mems_allowed? + */ +int cpuset_zone_allowed(struct zone *z) +{ + return in_interrupt() || + node_isset(z->zone_pgdat->node_id, current->mems_allowed); +} + +/* + * proc_cpuset_show() + * - Print tasks cpuset path into seq_file. + * - Used for /proc/<pid>/cpuset. + */ + +static int proc_cpuset_show(struct seq_file *m, void *v) +{ + struct cpuset *cs; + struct task_struct *tsk; + char *buf; + int retval = 0; + + buf = kmalloc(PAGE_SIZE, GFP_KERNEL); + if (!buf) + return -ENOMEM; + + tsk = m->private; + down(&cpuset_sem); + task_lock(tsk); + cs = tsk->cpuset; + task_unlock(tsk); + if (!cs) { + retval = -EINVAL; + goto out; + } + + retval = cpuset_path(cs, buf, PAGE_SIZE); + if (retval < 0) + goto out; + seq_puts(m, buf); + seq_putc(m, '\n'); +out: + up(&cpuset_sem); + kfree(buf); + return retval; +} + +static int cpuset_open(struct inode *inode, struct file *file) +{ + struct task_struct *tsk = PROC_I(inode)->task; + return single_open(file, proc_cpuset_show, tsk); +} + +struct file_operations proc_cpuset_operations = { + .open = cpuset_open, + .read = seq_read, + .llseek = seq_lseek, + .release = single_release, +}; + +/* Display task cpus_allowed, mems_allowed in /proc/<pid>/status file. */ +char *cpuset_task_status_allowed(struct task_struct *task, char *buffer) +{ + buffer += sprintf(buffer, "Cpus_allowed:\t"); + buffer += cpumask_scnprintf(buffer, PAGE_SIZE, task->cpus_allowed); + buffer += sprintf(buffer, "\n"); + buffer += sprintf(buffer, "Mems_allowed:\t"); + buffer += nodemask_scnprintf(buffer, PAGE_SIZE, task->mems_allowed); + buffer += sprintf(buffer, "\n"); + return buffer; +} |