commit b835996f628eadb55c5fb222ba46fe9395bf73c7
author Dipankar Sarma <dipankar@in.ibm.com> Fri Sep 09 13:04:14 2005 -0700
committer Linus Torvalds <torvalds@g5.osdl.org> Fri Sep 09 13:57:55 2005 -0700
tree d63d80585d197e1ffc299af4a0034049790fb197
parent ab2af1f5005069321c5d130f09cce577b03f43ef

[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

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(&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 @@
 		if(ttyp->magic != TTY_MAGIC)
 			ttyp =NULL;
 	}
-	spin_unlock(&current->files->file_lock);
+	rcu_read_unlock();
 	return ttyp;
 }