mirror of
https://github.com/edk2-porting/linux-next.git
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d919b33daf
Now that "struct proc_ops" exist we can start putting there stuff which could not fly with VFS "struct file_operations"... Most of fs/proc/inode.c file is dedicated to make open/read/.../close reliable in the event of disappearing /proc entries which usually happens if module is getting removed. Files like /proc/cpuinfo which never disappear simply do not need such protection. Save 2 atomic ops, 1 allocation, 1 free per open/read/close sequence for such "permanent" files. Enable "permanent" flag for /proc/cpuinfo /proc/kmsg /proc/modules /proc/slabinfo /proc/stat /proc/sysvipc/* /proc/swaps More will come once I figure out foolproof way to prevent out module authors from marking their stuff "permanent" for performance reasons when it is not. This should help with scalability: benchmark is "read /proc/cpuinfo R times by N threads scattered over the system". N R t, s (before) t, s (after) ----------------------------------------------------- 64 4096 1.582458 1.530502 -3.2% 256 4096 6.371926 6.125168 -3.9% 1024 4096 25.64888 24.47528 -4.6% Benchmark source: #include <chrono> #include <iostream> #include <thread> #include <vector> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> const int NR_CPUS = sysconf(_SC_NPROCESSORS_ONLN); int N; const char *filename; int R; int xxx = 0; int glue(int n) { cpu_set_t m; CPU_ZERO(&m); CPU_SET(n, &m); return sched_setaffinity(0, sizeof(cpu_set_t), &m); } void f(int n) { glue(n % NR_CPUS); while (*(volatile int *)&xxx == 0) { } for (int i = 0; i < R; i++) { int fd = open(filename, O_RDONLY); char buf[4096]; ssize_t rv = read(fd, buf, sizeof(buf)); asm volatile ("" :: "g" (rv)); close(fd); } } int main(int argc, char *argv[]) { if (argc < 4) { std::cerr << "usage: " << argv[0] << ' ' << "N /proc/filename R "; return 1; } N = atoi(argv[1]); filename = argv[2]; R = atoi(argv[3]); for (int i = 0; i < NR_CPUS; i++) { if (glue(i) == 0) break; } std::vector<std::thread> T; T.reserve(N); for (int i = 0; i < N; i++) { T.emplace_back(f, i); } auto t0 = std::chrono::system_clock::now(); { *(volatile int *)&xxx = 1; for (auto& t: T) { t.join(); } } auto t1 = std::chrono::system_clock::now(); std::chrono::duration<double> dt = t1 - t0; std::cout << dt.count() << ' '; return 0; } P.S.: Explicit randomization marker is added because adding non-function pointer will silently disable structure layout randomization. [akpm@linux-foundation.org: coding style fixes] Reported-by: kbuild test robot <lkp@intel.com> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Joe Perches <joe@perches.com> Link: http://lkml.kernel.org/r/20200222201539.GA22576@avx2 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
643 lines
16 KiB
C
643 lines
16 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* linux/fs/proc/inode.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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#include <linux/cache.h>
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#include <linux/time.h>
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#include <linux/proc_fs.h>
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#include <linux/kernel.h>
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#include <linux/pid_namespace.h>
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#include <linux/mm.h>
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#include <linux/string.h>
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#include <linux/stat.h>
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#include <linux/completion.h>
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#include <linux/poll.h>
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#include <linux/printk.h>
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#include <linux/file.h>
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#include <linux/limits.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/sysctl.h>
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#include <linux/seq_file.h>
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#include <linux/slab.h>
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#include <linux/mount.h>
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#include <linux/uaccess.h>
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#include "internal.h"
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static void proc_evict_inode(struct inode *inode)
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{
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struct proc_dir_entry *de;
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struct ctl_table_header *head;
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struct proc_inode *ei = PROC_I(inode);
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truncate_inode_pages_final(&inode->i_data);
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clear_inode(inode);
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/* Stop tracking associated processes */
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if (ei->pid) {
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proc_pid_evict_inode(ei);
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ei->pid = NULL;
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}
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/* Let go of any associated proc directory entry */
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de = ei->pde;
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if (de) {
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pde_put(de);
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ei->pde = NULL;
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}
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head = ei->sysctl;
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if (head) {
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RCU_INIT_POINTER(ei->sysctl, NULL);
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proc_sys_evict_inode(inode, head);
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}
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}
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static struct kmem_cache *proc_inode_cachep __ro_after_init;
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static struct kmem_cache *pde_opener_cache __ro_after_init;
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static struct inode *proc_alloc_inode(struct super_block *sb)
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{
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struct proc_inode *ei;
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ei = kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL);
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if (!ei)
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return NULL;
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ei->pid = NULL;
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ei->fd = 0;
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ei->op.proc_get_link = NULL;
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ei->pde = NULL;
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ei->sysctl = NULL;
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ei->sysctl_entry = NULL;
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INIT_HLIST_NODE(&ei->sibling_inodes);
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ei->ns_ops = NULL;
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return &ei->vfs_inode;
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}
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static void proc_free_inode(struct inode *inode)
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{
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kmem_cache_free(proc_inode_cachep, PROC_I(inode));
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}
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static void init_once(void *foo)
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{
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struct proc_inode *ei = (struct proc_inode *) foo;
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inode_init_once(&ei->vfs_inode);
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}
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void __init proc_init_kmemcache(void)
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{
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proc_inode_cachep = kmem_cache_create("proc_inode_cache",
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sizeof(struct proc_inode),
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0, (SLAB_RECLAIM_ACCOUNT|
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SLAB_MEM_SPREAD|SLAB_ACCOUNT|
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SLAB_PANIC),
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init_once);
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pde_opener_cache =
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kmem_cache_create("pde_opener", sizeof(struct pde_opener), 0,
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SLAB_ACCOUNT|SLAB_PANIC, NULL);
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proc_dir_entry_cache = kmem_cache_create_usercopy(
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"proc_dir_entry", SIZEOF_PDE, 0, SLAB_PANIC,
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offsetof(struct proc_dir_entry, inline_name),
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SIZEOF_PDE_INLINE_NAME, NULL);
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BUILD_BUG_ON(sizeof(struct proc_dir_entry) >= SIZEOF_PDE);
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}
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void proc_invalidate_siblings_dcache(struct hlist_head *inodes, spinlock_t *lock)
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{
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struct inode *inode;
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struct proc_inode *ei;
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struct hlist_node *node;
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struct super_block *old_sb = NULL;
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rcu_read_lock();
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for (;;) {
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struct super_block *sb;
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node = hlist_first_rcu(inodes);
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if (!node)
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break;
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ei = hlist_entry(node, struct proc_inode, sibling_inodes);
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spin_lock(lock);
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hlist_del_init_rcu(&ei->sibling_inodes);
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spin_unlock(lock);
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inode = &ei->vfs_inode;
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sb = inode->i_sb;
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if ((sb != old_sb) && !atomic_inc_not_zero(&sb->s_active))
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continue;
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inode = igrab(inode);
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rcu_read_unlock();
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if (sb != old_sb) {
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if (old_sb)
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deactivate_super(old_sb);
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old_sb = sb;
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}
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if (unlikely(!inode)) {
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rcu_read_lock();
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continue;
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}
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if (S_ISDIR(inode->i_mode)) {
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struct dentry *dir = d_find_any_alias(inode);
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if (dir) {
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d_invalidate(dir);
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dput(dir);
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}
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} else {
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struct dentry *dentry;
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while ((dentry = d_find_alias(inode))) {
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d_invalidate(dentry);
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dput(dentry);
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}
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}
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iput(inode);
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rcu_read_lock();
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}
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rcu_read_unlock();
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if (old_sb)
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deactivate_super(old_sb);
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}
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static int proc_show_options(struct seq_file *seq, struct dentry *root)
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{
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struct super_block *sb = root->d_sb;
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struct pid_namespace *pid = sb->s_fs_info;
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if (!gid_eq(pid->pid_gid, GLOBAL_ROOT_GID))
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seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, pid->pid_gid));
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if (pid->hide_pid != HIDEPID_OFF)
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seq_printf(seq, ",hidepid=%u", pid->hide_pid);
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return 0;
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}
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const struct super_operations proc_sops = {
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.alloc_inode = proc_alloc_inode,
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.free_inode = proc_free_inode,
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.drop_inode = generic_delete_inode,
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.evict_inode = proc_evict_inode,
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.statfs = simple_statfs,
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.show_options = proc_show_options,
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};
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enum {BIAS = -1U<<31};
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static inline int use_pde(struct proc_dir_entry *pde)
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{
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return likely(atomic_inc_unless_negative(&pde->in_use));
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}
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static void unuse_pde(struct proc_dir_entry *pde)
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{
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if (unlikely(atomic_dec_return(&pde->in_use) == BIAS))
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complete(pde->pde_unload_completion);
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}
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/* pde is locked on entry, unlocked on exit */
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static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo)
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__releases(&pde->pde_unload_lock)
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{
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/*
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* close() (proc_reg_release()) can't delete an entry and proceed:
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* ->release hook needs to be available at the right moment.
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*
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* rmmod (remove_proc_entry() et al) can't delete an entry and proceed:
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* "struct file" needs to be available at the right moment.
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*
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* Therefore, first process to enter this function does ->release() and
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* signals its completion to the other process which does nothing.
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*/
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if (pdeo->closing) {
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/* somebody else is doing that, just wait */
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DECLARE_COMPLETION_ONSTACK(c);
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pdeo->c = &c;
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spin_unlock(&pde->pde_unload_lock);
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wait_for_completion(&c);
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} else {
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struct file *file;
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struct completion *c;
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pdeo->closing = true;
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spin_unlock(&pde->pde_unload_lock);
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file = pdeo->file;
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pde->proc_ops->proc_release(file_inode(file), file);
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spin_lock(&pde->pde_unload_lock);
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/* After ->release. */
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list_del(&pdeo->lh);
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c = pdeo->c;
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spin_unlock(&pde->pde_unload_lock);
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if (unlikely(c))
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complete(c);
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kmem_cache_free(pde_opener_cache, pdeo);
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}
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}
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void proc_entry_rundown(struct proc_dir_entry *de)
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{
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DECLARE_COMPLETION_ONSTACK(c);
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/* Wait until all existing callers into module are done. */
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de->pde_unload_completion = &c;
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if (atomic_add_return(BIAS, &de->in_use) != BIAS)
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wait_for_completion(&c);
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/* ->pde_openers list can't grow from now on. */
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spin_lock(&de->pde_unload_lock);
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while (!list_empty(&de->pde_openers)) {
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struct pde_opener *pdeo;
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pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh);
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close_pdeo(de, pdeo);
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spin_lock(&de->pde_unload_lock);
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}
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spin_unlock(&de->pde_unload_lock);
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}
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static loff_t pde_lseek(struct proc_dir_entry *pde, struct file *file, loff_t offset, int whence)
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{
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typeof_member(struct proc_ops, proc_lseek) lseek;
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lseek = pde->proc_ops->proc_lseek;
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if (!lseek)
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lseek = default_llseek;
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return lseek(file, offset, whence);
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}
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static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
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{
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struct proc_dir_entry *pde = PDE(file_inode(file));
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loff_t rv = -EINVAL;
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if (pde_is_permanent(pde)) {
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return pde_lseek(pde, file, offset, whence);
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} else if (use_pde(pde)) {
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rv = pde_lseek(pde, file, offset, whence);
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unuse_pde(pde);
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}
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return rv;
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}
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static ssize_t pde_read(struct proc_dir_entry *pde, struct file *file, char __user *buf, size_t count, loff_t *ppos)
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{
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typeof_member(struct proc_ops, proc_read) read;
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read = pde->proc_ops->proc_read;
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if (read)
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return read(file, buf, count, ppos);
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return -EIO;
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}
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static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
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{
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struct proc_dir_entry *pde = PDE(file_inode(file));
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ssize_t rv = -EIO;
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if (pde_is_permanent(pde)) {
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return pde_read(pde, file, buf, count, ppos);
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} else if (use_pde(pde)) {
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rv = pde_read(pde, file, buf, count, ppos);
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unuse_pde(pde);
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}
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return rv;
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}
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static ssize_t pde_write(struct proc_dir_entry *pde, struct file *file, const char __user *buf, size_t count, loff_t *ppos)
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{
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typeof_member(struct proc_ops, proc_write) write;
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write = pde->proc_ops->proc_write;
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if (write)
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return write(file, buf, count, ppos);
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return -EIO;
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}
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static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
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{
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struct proc_dir_entry *pde = PDE(file_inode(file));
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ssize_t rv = -EIO;
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if (pde_is_permanent(pde)) {
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return pde_write(pde, file, buf, count, ppos);
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} else if (use_pde(pde)) {
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rv = pde_write(pde, file, buf, count, ppos);
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unuse_pde(pde);
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}
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return rv;
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}
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static __poll_t pde_poll(struct proc_dir_entry *pde, struct file *file, struct poll_table_struct *pts)
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{
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typeof_member(struct proc_ops, proc_poll) poll;
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poll = pde->proc_ops->proc_poll;
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if (poll)
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return poll(file, pts);
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return DEFAULT_POLLMASK;
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}
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static __poll_t proc_reg_poll(struct file *file, struct poll_table_struct *pts)
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{
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struct proc_dir_entry *pde = PDE(file_inode(file));
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__poll_t rv = DEFAULT_POLLMASK;
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if (pde_is_permanent(pde)) {
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return pde_poll(pde, file, pts);
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} else if (use_pde(pde)) {
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rv = pde_poll(pde, file, pts);
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unuse_pde(pde);
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}
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return rv;
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}
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static long pde_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg)
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{
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typeof_member(struct proc_ops, proc_ioctl) ioctl;
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ioctl = pde->proc_ops->proc_ioctl;
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if (ioctl)
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return ioctl(file, cmd, arg);
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return -ENOTTY;
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}
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static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
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{
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struct proc_dir_entry *pde = PDE(file_inode(file));
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long rv = -ENOTTY;
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if (pde_is_permanent(pde)) {
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return pde_ioctl(pde, file, cmd, arg);
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} else if (use_pde(pde)) {
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rv = pde_ioctl(pde, file, cmd, arg);
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unuse_pde(pde);
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}
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return rv;
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}
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#ifdef CONFIG_COMPAT
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static long pde_compat_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg)
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{
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typeof_member(struct proc_ops, proc_compat_ioctl) compat_ioctl;
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compat_ioctl = pde->proc_ops->proc_compat_ioctl;
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if (compat_ioctl)
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return compat_ioctl(file, cmd, arg);
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return -ENOTTY;
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}
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static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
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{
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struct proc_dir_entry *pde = PDE(file_inode(file));
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long rv = -ENOTTY;
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if (pde_is_permanent(pde)) {
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return pde_compat_ioctl(pde, file, cmd, arg);
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} else if (use_pde(pde)) {
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rv = pde_compat_ioctl(pde, file, cmd, arg);
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unuse_pde(pde);
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}
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return rv;
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}
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#endif
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static int pde_mmap(struct proc_dir_entry *pde, struct file *file, struct vm_area_struct *vma)
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{
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typeof_member(struct proc_ops, proc_mmap) mmap;
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mmap = pde->proc_ops->proc_mmap;
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if (mmap)
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return mmap(file, vma);
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return -EIO;
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}
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static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma)
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{
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struct proc_dir_entry *pde = PDE(file_inode(file));
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int rv = -EIO;
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if (pde_is_permanent(pde)) {
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return pde_mmap(pde, file, vma);
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} else if (use_pde(pde)) {
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rv = pde_mmap(pde, file, vma);
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unuse_pde(pde);
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}
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return rv;
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}
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static unsigned long
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pde_get_unmapped_area(struct proc_dir_entry *pde, struct file *file, unsigned long orig_addr,
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unsigned long len, unsigned long pgoff,
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unsigned long flags)
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{
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typeof_member(struct proc_ops, proc_get_unmapped_area) get_area;
|
|
|
|
get_area = pde->proc_ops->proc_get_unmapped_area;
|
|
#ifdef CONFIG_MMU
|
|
if (!get_area)
|
|
get_area = current->mm->get_unmapped_area;
|
|
#endif
|
|
if (get_area)
|
|
return get_area(file, orig_addr, len, pgoff, flags);
|
|
return orig_addr;
|
|
}
|
|
|
|
static unsigned long
|
|
proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr,
|
|
unsigned long len, unsigned long pgoff,
|
|
unsigned long flags)
|
|
{
|
|
struct proc_dir_entry *pde = PDE(file_inode(file));
|
|
unsigned long rv = -EIO;
|
|
|
|
if (pde_is_permanent(pde)) {
|
|
return pde_get_unmapped_area(pde, file, orig_addr, len, pgoff, flags);
|
|
} else if (use_pde(pde)) {
|
|
rv = pde_get_unmapped_area(pde, file, orig_addr, len, pgoff, flags);
|
|
unuse_pde(pde);
|
|
}
|
|
return rv;
|
|
}
|
|
|
|
static int proc_reg_open(struct inode *inode, struct file *file)
|
|
{
|
|
struct proc_dir_entry *pde = PDE(inode);
|
|
int rv = 0;
|
|
typeof_member(struct proc_ops, proc_open) open;
|
|
typeof_member(struct proc_ops, proc_release) release;
|
|
struct pde_opener *pdeo;
|
|
|
|
if (pde_is_permanent(pde)) {
|
|
open = pde->proc_ops->proc_open;
|
|
if (open)
|
|
rv = open(inode, file);
|
|
return rv;
|
|
}
|
|
|
|
/*
|
|
* Ensure that
|
|
* 1) PDE's ->release hook will be called no matter what
|
|
* either normally by close()/->release, or forcefully by
|
|
* rmmod/remove_proc_entry.
|
|
*
|
|
* 2) rmmod isn't blocked by opening file in /proc and sitting on
|
|
* the descriptor (including "rmmod foo </proc/foo" scenario).
|
|
*
|
|
* Save every "struct file" with custom ->release hook.
|
|
*/
|
|
if (!use_pde(pde))
|
|
return -ENOENT;
|
|
|
|
release = pde->proc_ops->proc_release;
|
|
if (release) {
|
|
pdeo = kmem_cache_alloc(pde_opener_cache, GFP_KERNEL);
|
|
if (!pdeo) {
|
|
rv = -ENOMEM;
|
|
goto out_unuse;
|
|
}
|
|
}
|
|
|
|
open = pde->proc_ops->proc_open;
|
|
if (open)
|
|
rv = open(inode, file);
|
|
|
|
if (release) {
|
|
if (rv == 0) {
|
|
/* To know what to release. */
|
|
pdeo->file = file;
|
|
pdeo->closing = false;
|
|
pdeo->c = NULL;
|
|
spin_lock(&pde->pde_unload_lock);
|
|
list_add(&pdeo->lh, &pde->pde_openers);
|
|
spin_unlock(&pde->pde_unload_lock);
|
|
} else
|
|
kmem_cache_free(pde_opener_cache, pdeo);
|
|
}
|
|
|
|
out_unuse:
|
|
unuse_pde(pde);
|
|
return rv;
|
|
}
|
|
|
|
static int proc_reg_release(struct inode *inode, struct file *file)
|
|
{
|
|
struct proc_dir_entry *pde = PDE(inode);
|
|
struct pde_opener *pdeo;
|
|
|
|
if (pde_is_permanent(pde)) {
|
|
typeof_member(struct proc_ops, proc_release) release;
|
|
|
|
release = pde->proc_ops->proc_release;
|
|
if (release) {
|
|
return release(inode, file);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
spin_lock(&pde->pde_unload_lock);
|
|
list_for_each_entry(pdeo, &pde->pde_openers, lh) {
|
|
if (pdeo->file == file) {
|
|
close_pdeo(pde, pdeo);
|
|
return 0;
|
|
}
|
|
}
|
|
spin_unlock(&pde->pde_unload_lock);
|
|
return 0;
|
|
}
|
|
|
|
static const struct file_operations proc_reg_file_ops = {
|
|
.llseek = proc_reg_llseek,
|
|
.read = proc_reg_read,
|
|
.write = proc_reg_write,
|
|
.poll = proc_reg_poll,
|
|
.unlocked_ioctl = proc_reg_unlocked_ioctl,
|
|
#ifdef CONFIG_COMPAT
|
|
.compat_ioctl = proc_reg_compat_ioctl,
|
|
#endif
|
|
.mmap = proc_reg_mmap,
|
|
.get_unmapped_area = proc_reg_get_unmapped_area,
|
|
.open = proc_reg_open,
|
|
.release = proc_reg_release,
|
|
};
|
|
|
|
#ifdef CONFIG_COMPAT
|
|
static const struct file_operations proc_reg_file_ops_no_compat = {
|
|
.llseek = proc_reg_llseek,
|
|
.read = proc_reg_read,
|
|
.write = proc_reg_write,
|
|
.poll = proc_reg_poll,
|
|
.unlocked_ioctl = proc_reg_unlocked_ioctl,
|
|
.mmap = proc_reg_mmap,
|
|
.get_unmapped_area = proc_reg_get_unmapped_area,
|
|
.open = proc_reg_open,
|
|
.release = proc_reg_release,
|
|
};
|
|
#endif
|
|
|
|
static void proc_put_link(void *p)
|
|
{
|
|
unuse_pde(p);
|
|
}
|
|
|
|
static const char *proc_get_link(struct dentry *dentry,
|
|
struct inode *inode,
|
|
struct delayed_call *done)
|
|
{
|
|
struct proc_dir_entry *pde = PDE(inode);
|
|
if (!use_pde(pde))
|
|
return ERR_PTR(-EINVAL);
|
|
set_delayed_call(done, proc_put_link, pde);
|
|
return pde->data;
|
|
}
|
|
|
|
const struct inode_operations proc_link_inode_operations = {
|
|
.get_link = proc_get_link,
|
|
};
|
|
|
|
struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
|
|
{
|
|
struct inode *inode = new_inode_pseudo(sb);
|
|
|
|
if (inode) {
|
|
inode->i_ino = de->low_ino;
|
|
inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
|
|
PROC_I(inode)->pde = de;
|
|
|
|
if (is_empty_pde(de)) {
|
|
make_empty_dir_inode(inode);
|
|
return inode;
|
|
}
|
|
if (de->mode) {
|
|
inode->i_mode = de->mode;
|
|
inode->i_uid = de->uid;
|
|
inode->i_gid = de->gid;
|
|
}
|
|
if (de->size)
|
|
inode->i_size = de->size;
|
|
if (de->nlink)
|
|
set_nlink(inode, de->nlink);
|
|
|
|
if (S_ISREG(inode->i_mode)) {
|
|
inode->i_op = de->proc_iops;
|
|
inode->i_fop = &proc_reg_file_ops;
|
|
#ifdef CONFIG_COMPAT
|
|
if (!de->proc_ops->proc_compat_ioctl) {
|
|
inode->i_fop = &proc_reg_file_ops_no_compat;
|
|
}
|
|
#endif
|
|
} else if (S_ISDIR(inode->i_mode)) {
|
|
inode->i_op = de->proc_iops;
|
|
inode->i_fop = de->proc_dir_ops;
|
|
} else if (S_ISLNK(inode->i_mode)) {
|
|
inode->i_op = de->proc_iops;
|
|
inode->i_fop = NULL;
|
|
} else
|
|
BUG();
|
|
} else
|
|
pde_put(de);
|
|
return inode;
|
|
}
|