[PATCH] files: lock-free fd look-up
With the use of RCU in files structure, the look-up of files using fds can now
be lock-free. The lookup is protected by rcu_read_lock()/rcu_read_unlock().
This patch changes the readers to use lock-free lookup.
Signed-off-by: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: Ravikiran Thirumalai <kiran_th@gmail.com>
Signed-off-by: Dipankar Sarma <dipankar@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/mips/kernel/irixioctl.c b/arch/mips/kernel/irixioctl.c
index 4cd3d38..3cdc223 100644
--- a/arch/mips/kernel/irixioctl.c
+++ b/arch/mips/kernel/irixioctl.c
@@ -14,6 +14,7 @@
#include <linux/syscalls.h>
#include <linux/tty.h>
#include <linux/file.h>
+#include <linux/rcupdate.h>
#include <asm/uaccess.h>
#include <asm/ioctl.h>
@@ -33,7 +34,7 @@
struct file *filp;
struct tty_struct *ttyp = NULL;
- spin_lock(¤t->files->file_lock);
+ rcu_read_lock();
filp = fcheck(fd);
if(filp && filp->private_data) {
ttyp = (struct tty_struct *) filp->private_data;
@@ -41,7 +42,7 @@
if(ttyp->magic != TTY_MAGIC)
ttyp =NULL;
}
- spin_unlock(¤t->files->file_lock);
+ rcu_read_unlock();
return ttyp;
}
diff --git a/arch/sparc64/solaris/ioctl.c b/arch/sparc64/solaris/ioctl.c
index 3747664..be0a054 100644
--- a/arch/sparc64/solaris/ioctl.c
+++ b/arch/sparc64/solaris/ioctl.c
@@ -24,6 +24,7 @@
#include <linux/netdevice.h>
#include <linux/mtio.h>
#include <linux/time.h>
+#include <linux/rcupdate.h>
#include <linux/compat.h>
#include <net/sock.h>
@@ -295,16 +296,16 @@
struct inode *ino;
struct fdtable *fdt;
/* I wonder which of these tests are superfluous... --patrik */
- spin_lock(¤t->files->file_lock);
+ rcu_read_lock();
fdt = files_fdtable(current->files);
if (! fdt->fd[fd] ||
! fdt->fd[fd]->f_dentry ||
! (ino = fdt->fd[fd]->f_dentry->d_inode) ||
! S_ISSOCK(ino->i_mode)) {
- spin_unlock(¤t->files->file_lock);
+ rcu_read_unlock();
return TBADF;
}
- spin_unlock(¤t->files->file_lock);
+ rcu_read_unlock();
switch (cmd & 0xff) {
case 109: /* SI_SOCKPARAMS */
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 0bfc7af..e5953f3 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -2480,7 +2480,7 @@
}
task_lock(p);
if (p->files) {
- spin_lock(&p->files->file_lock);
+ rcu_read_lock();
fdt = files_fdtable(p->files);
for (i=0; i < fdt->max_fds; i++) {
filp = fcheck_files(p->files, i);
@@ -2495,7 +2495,7 @@
break;
}
}
- spin_unlock(&p->files->file_lock);
+ rcu_read_unlock();
}
task_unlock(p);
} while_each_task_pid(session, PIDTYPE_SID, p);
diff --git a/fs/fcntl.c b/fs/fcntl.c
index d2f3ed8..863b46e 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -40,10 +40,10 @@
struct files_struct *files = current->files;
struct fdtable *fdt;
int res;
- spin_lock(&files->file_lock);
+ rcu_read_lock();
fdt = files_fdtable(files);
res = FD_ISSET(fd, fdt->close_on_exec);
- spin_unlock(&files->file_lock);
+ rcu_read_unlock();
return res;
}
diff --git a/fs/proc/base.c b/fs/proc/base.c
index d0087a0..23db452 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -62,6 +62,7 @@
#include <linux/namespace.h>
#include <linux/mm.h>
#include <linux/smp_lock.h>
+#include <linux/rcupdate.h>
#include <linux/kallsyms.h>
#include <linux/mount.h>
#include <linux/security.h>
@@ -283,16 +284,16 @@
files = get_files_struct(task);
if (files) {
- spin_lock(&files->file_lock);
+ rcu_read_lock();
file = fcheck_files(files, fd);
if (file) {
*mnt = mntget(file->f_vfsmnt);
*dentry = dget(file->f_dentry);
- spin_unlock(&files->file_lock);
+ rcu_read_unlock();
put_files_struct(files);
return 0;
}
- spin_unlock(&files->file_lock);
+ rcu_read_unlock();
put_files_struct(files);
}
return -ENOENT;
@@ -1062,7 +1063,7 @@
files = get_files_struct(p);
if (!files)
goto out;
- spin_lock(&files->file_lock);
+ rcu_read_lock();
fdt = files_fdtable(files);
for (fd = filp->f_pos-2;
fd < fdt->max_fds;
@@ -1071,7 +1072,7 @@
if (!fcheck_files(files, fd))
continue;
- spin_unlock(&files->file_lock);
+ rcu_read_unlock();
j = NUMBUF;
i = fd;
@@ -1083,12 +1084,12 @@
ino = fake_ino(tid, PROC_TID_FD_DIR + fd);
if (filldir(dirent, buf+j, NUMBUF-j, fd+2, ino, DT_LNK) < 0) {
- spin_lock(&files->file_lock);
+ rcu_read_lock();
break;
}
- spin_lock(&files->file_lock);
+ rcu_read_lock();
}
- spin_unlock(&files->file_lock);
+ rcu_read_unlock();
put_files_struct(files);
}
out:
@@ -1263,9 +1264,9 @@
files = get_files_struct(task);
if (files) {
- spin_lock(&files->file_lock);
+ rcu_read_lock();
if (fcheck_files(files, fd)) {
- spin_unlock(&files->file_lock);
+ rcu_read_unlock();
put_files_struct(files);
if (task_dumpable(task)) {
inode->i_uid = task->euid;
@@ -1277,7 +1278,7 @@
security_task_to_inode(task, inode);
return 1;
}
- spin_unlock(&files->file_lock);
+ rcu_read_unlock();
put_files_struct(files);
}
d_drop(dentry);
@@ -1369,7 +1370,7 @@
if (!files)
goto out_unlock;
inode->i_mode = S_IFLNK;
- spin_lock(&files->file_lock);
+ rcu_read_lock();
file = fcheck_files(files, fd);
if (!file)
goto out_unlock2;
@@ -1377,7 +1378,7 @@
inode->i_mode |= S_IRUSR | S_IXUSR;
if (file->f_mode & 2)
inode->i_mode |= S_IWUSR | S_IXUSR;
- spin_unlock(&files->file_lock);
+ rcu_read_unlock();
put_files_struct(files);
inode->i_op = &proc_pid_link_inode_operations;
inode->i_size = 64;
@@ -1387,7 +1388,7 @@
return NULL;
out_unlock2:
- spin_unlock(&files->file_lock);
+ rcu_read_unlock();
put_files_struct(files);
out_unlock:
iput(inode);
diff --git a/fs/select.c b/fs/select.c
index 2e56325..f10a103 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -22,6 +22,7 @@
#include <linux/personality.h> /* for STICKY_TIMEOUTS */
#include <linux/file.h>
#include <linux/fs.h>
+#include <linux/rcupdate.h>
#include <asm/uaccess.h>
@@ -185,9 +186,9 @@
int retval, i;
long __timeout = *timeout;
- spin_lock(¤t->files->file_lock);
+ rcu_read_lock();
retval = max_select_fd(n, fds);
- spin_unlock(¤t->files->file_lock);
+ rcu_read_unlock();
if (retval < 0)
return retval;
@@ -329,8 +330,10 @@
goto out_nofds;
/* max_fdset can increase, so grab it once to avoid race */
+ rcu_read_lock();
fdt = files_fdtable(current->files);
max_fdset = fdt->max_fdset;
+ rcu_read_unlock();
if (n > max_fdset)
n = max_fdset;
@@ -469,10 +472,14 @@
struct poll_list *head;
struct poll_list *walk;
struct fdtable *fdt;
+ int max_fdset;
/* Do a sanity check on nfds ... */
+ rcu_read_lock();
fdt = files_fdtable(current->files);
- if (nfds > fdt->max_fdset && nfds > OPEN_MAX)
+ max_fdset = fdt->max_fdset;
+ rcu_read_unlock();
+ if (nfds > max_fdset && nfds > OPEN_MAX)
return -EINVAL;
if (timeout) {
diff --git a/net/ipv4/netfilter/ipt_owner.c b/net/ipv4/netfilter/ipt_owner.c
index c1889f8..0cee286 100644
--- a/net/ipv4/netfilter/ipt_owner.c
+++ b/net/ipv4/netfilter/ipt_owner.c
@@ -11,6 +11,7 @@
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/file.h>
+#include <linux/rcupdate.h>
#include <net/sock.h>
#include <linux/netfilter_ipv4/ipt_owner.h>
diff --git a/net/ipv6/netfilter/ip6t_owner.c b/net/ipv6/netfilter/ip6t_owner.c
index 9b91dec..4de4cda 100644
--- a/net/ipv6/netfilter/ip6t_owner.c
+++ b/net/ipv6/netfilter/ip6t_owner.c
@@ -11,6 +11,7 @@
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/file.h>
+#include <linux/rcupdate.h>
#include <net/sock.h>
#include <linux/netfilter_ipv6/ip6t_owner.h>
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index acb5a49..f40c822 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -1652,7 +1652,7 @@
continue;
}
if (devnull) {
- atomic_inc(&devnull->f_count);
+ rcuref_inc(&devnull->f_count);
} else {
devnull = dentry_open(dget(selinux_null), mntget(selinuxfs_mount), O_RDWR);
if (!devnull) {
