From b835996f628eadb55c5fb222ba46fe9395bf73c7 Mon Sep 17 00:00:00 2001
From: Dipankar Sarma <dipankar@in.ibm.com>
Date: Fri, 9 Sep 2005 13:04:14 -0700
Subject: [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>
---
 arch/mips/kernel/irixioctl.c | 5 +++--
 arch/sparc64/solaris/ioctl.c | 7 ++++---
 2 files changed, 7 insertions(+), 5 deletions(-)

(limited to 'arch')

diff --git a/arch/mips/kernel/irixioctl.c b/arch/mips/kernel/irixioctl.c
index 4cd3d38a22c2..3cdc22346f4c 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 @@ static struct tty_struct *get_tty(int fd)
 	struct file *filp;
 	struct tty_struct *ttyp = NULL;
 
-	spin_lock(&current->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 @@ static struct tty_struct *get_tty(int fd)
 		if(ttyp->magic != TTY_MAGIC)
 			ttyp =NULL;
 	}
-	spin_unlock(&current->files->file_lock);
+	rcu_read_unlock();
 	return ttyp;
 }
 
diff --git a/arch/sparc64/solaris/ioctl.c b/arch/sparc64/solaris/ioctl.c
index 374766455f5e..be0a054e3ed6 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 @@ static inline int solaris_sockmod(unsigned int fd, unsigned int cmd, u32 arg)
 	struct inode *ino;
 	struct fdtable *fdt;
 	/* I wonder which of these tests are superfluous... --patrik */
-	spin_lock(&current->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(&current->files->file_lock);
+		rcu_read_unlock();
 		return TBADF;
 	}
-	spin_unlock(&current->files->file_lock);
+	rcu_read_unlock();
 	
 	switch (cmd & 0xff) {
 	case 109: /* SI_SOCKPARAMS */
-- 
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