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>
183 lines
7.1 KiB
C
183 lines
7.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* The proc filesystem constants/structures
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*/
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#ifndef _LINUX_PROC_FS_H
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#define _LINUX_PROC_FS_H
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#include <linux/compiler.h>
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#include <linux/types.h>
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#include <linux/fs.h>
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struct proc_dir_entry;
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struct seq_file;
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struct seq_operations;
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enum {
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/*
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* All /proc entries using this ->proc_ops instance are never removed.
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*
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* If in doubt, ignore this flag.
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*/
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#ifdef MODULE
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PROC_ENTRY_PERMANENT = 0U,
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#else
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PROC_ENTRY_PERMANENT = 1U << 0,
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#endif
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};
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struct proc_ops {
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unsigned int proc_flags;
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int (*proc_open)(struct inode *, struct file *);
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ssize_t (*proc_read)(struct file *, char __user *, size_t, loff_t *);
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ssize_t (*proc_write)(struct file *, const char __user *, size_t, loff_t *);
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loff_t (*proc_lseek)(struct file *, loff_t, int);
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int (*proc_release)(struct inode *, struct file *);
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__poll_t (*proc_poll)(struct file *, struct poll_table_struct *);
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long (*proc_ioctl)(struct file *, unsigned int, unsigned long);
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#ifdef CONFIG_COMPAT
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long (*proc_compat_ioctl)(struct file *, unsigned int, unsigned long);
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#endif
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int (*proc_mmap)(struct file *, struct vm_area_struct *);
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unsigned long (*proc_get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
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} __randomize_layout;
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#ifdef CONFIG_PROC_FS
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typedef int (*proc_write_t)(struct file *, char *, size_t);
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extern void proc_root_init(void);
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extern void proc_flush_pid(struct pid *);
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extern struct proc_dir_entry *proc_symlink(const char *,
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struct proc_dir_entry *, const char *);
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extern struct proc_dir_entry *proc_mkdir(const char *, struct proc_dir_entry *);
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extern struct proc_dir_entry *proc_mkdir_data(const char *, umode_t,
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struct proc_dir_entry *, void *);
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extern struct proc_dir_entry *proc_mkdir_mode(const char *, umode_t,
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struct proc_dir_entry *);
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struct proc_dir_entry *proc_create_mount_point(const char *name);
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struct proc_dir_entry *proc_create_seq_private(const char *name, umode_t mode,
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struct proc_dir_entry *parent, const struct seq_operations *ops,
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unsigned int state_size, void *data);
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#define proc_create_seq_data(name, mode, parent, ops, data) \
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proc_create_seq_private(name, mode, parent, ops, 0, data)
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#define proc_create_seq(name, mode, parent, ops) \
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proc_create_seq_private(name, mode, parent, ops, 0, NULL)
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struct proc_dir_entry *proc_create_single_data(const char *name, umode_t mode,
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struct proc_dir_entry *parent,
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int (*show)(struct seq_file *, void *), void *data);
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#define proc_create_single(name, mode, parent, show) \
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proc_create_single_data(name, mode, parent, show, NULL)
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extern struct proc_dir_entry *proc_create_data(const char *, umode_t,
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struct proc_dir_entry *,
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const struct proc_ops *,
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void *);
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struct proc_dir_entry *proc_create(const char *name, umode_t mode, struct proc_dir_entry *parent, const struct proc_ops *proc_ops);
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extern void proc_set_size(struct proc_dir_entry *, loff_t);
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extern void proc_set_user(struct proc_dir_entry *, kuid_t, kgid_t);
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extern void *PDE_DATA(const struct inode *);
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extern void *proc_get_parent_data(const struct inode *);
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extern void proc_remove(struct proc_dir_entry *);
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extern void remove_proc_entry(const char *, struct proc_dir_entry *);
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extern int remove_proc_subtree(const char *, struct proc_dir_entry *);
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struct proc_dir_entry *proc_create_net_data(const char *name, umode_t mode,
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struct proc_dir_entry *parent, const struct seq_operations *ops,
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unsigned int state_size, void *data);
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#define proc_create_net(name, mode, parent, ops, state_size) \
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proc_create_net_data(name, mode, parent, ops, state_size, NULL)
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struct proc_dir_entry *proc_create_net_single(const char *name, umode_t mode,
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struct proc_dir_entry *parent,
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int (*show)(struct seq_file *, void *), void *data);
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struct proc_dir_entry *proc_create_net_data_write(const char *name, umode_t mode,
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struct proc_dir_entry *parent,
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const struct seq_operations *ops,
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proc_write_t write,
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unsigned int state_size, void *data);
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struct proc_dir_entry *proc_create_net_single_write(const char *name, umode_t mode,
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struct proc_dir_entry *parent,
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int (*show)(struct seq_file *, void *),
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proc_write_t write,
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void *data);
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extern struct pid *tgid_pidfd_to_pid(const struct file *file);
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#ifdef CONFIG_PROC_PID_ARCH_STATUS
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/*
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* The architecture which selects CONFIG_PROC_PID_ARCH_STATUS must
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* provide proc_pid_arch_status() definition.
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*/
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int proc_pid_arch_status(struct seq_file *m, struct pid_namespace *ns,
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struct pid *pid, struct task_struct *task);
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#endif /* CONFIG_PROC_PID_ARCH_STATUS */
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#else /* CONFIG_PROC_FS */
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static inline void proc_root_init(void)
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{
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}
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static inline void proc_flush_pid(struct pid *pid)
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{
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}
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static inline struct proc_dir_entry *proc_symlink(const char *name,
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struct proc_dir_entry *parent,const char *dest) { return NULL;}
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static inline struct proc_dir_entry *proc_mkdir(const char *name,
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struct proc_dir_entry *parent) {return NULL;}
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static inline struct proc_dir_entry *proc_create_mount_point(const char *name) { return NULL; }
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static inline struct proc_dir_entry *proc_mkdir_data(const char *name,
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umode_t mode, struct proc_dir_entry *parent, void *data) { return NULL; }
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static inline struct proc_dir_entry *proc_mkdir_mode(const char *name,
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umode_t mode, struct proc_dir_entry *parent) { return NULL; }
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#define proc_create_seq_private(name, mode, parent, ops, size, data) ({NULL;})
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#define proc_create_seq_data(name, mode, parent, ops, data) ({NULL;})
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#define proc_create_seq(name, mode, parent, ops) ({NULL;})
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#define proc_create_single(name, mode, parent, show) ({NULL;})
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#define proc_create_single_data(name, mode, parent, show, data) ({NULL;})
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#define proc_create(name, mode, parent, proc_ops) ({NULL;})
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#define proc_create_data(name, mode, parent, proc_ops, data) ({NULL;})
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static inline void proc_set_size(struct proc_dir_entry *de, loff_t size) {}
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static inline void proc_set_user(struct proc_dir_entry *de, kuid_t uid, kgid_t gid) {}
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static inline void *PDE_DATA(const struct inode *inode) {BUG(); return NULL;}
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static inline void *proc_get_parent_data(const struct inode *inode) { BUG(); return NULL; }
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static inline void proc_remove(struct proc_dir_entry *de) {}
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#define remove_proc_entry(name, parent) do {} while (0)
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static inline int remove_proc_subtree(const char *name, struct proc_dir_entry *parent) { return 0; }
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#define proc_create_net_data(name, mode, parent, ops, state_size, data) ({NULL;})
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#define proc_create_net(name, mode, parent, state_size, ops) ({NULL;})
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#define proc_create_net_single(name, mode, parent, show, data) ({NULL;})
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static inline struct pid *tgid_pidfd_to_pid(const struct file *file)
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{
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return ERR_PTR(-EBADF);
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}
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#endif /* CONFIG_PROC_FS */
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struct net;
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static inline struct proc_dir_entry *proc_net_mkdir(
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struct net *net, const char *name, struct proc_dir_entry *parent)
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{
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return proc_mkdir_data(name, 0, parent, net);
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}
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struct ns_common;
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int open_related_ns(struct ns_common *ns,
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struct ns_common *(*get_ns)(struct ns_common *ns));
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/* get the associated pid namespace for a file in procfs */
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static inline struct pid_namespace *proc_pid_ns(const struct inode *inode)
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{
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return inode->i_sb->s_fs_info;
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}
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#endif /* _LINUX_PROC_FS_H */
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