From: Roland Dreier <rolandd@cisco.com>
Date: Fri, 25 Jul 2008 03:36:59 +0000 (-0700)
Subject: RDMA/ucm: BKL is not needed for ib_ucm_open()
X-Git-Tag: upstream/snapshot3+hdmi~23350^2~1
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=5ba18b186c979283a2bf75a28b7ea325184b0c08;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git

RDMA/ucm: BKL is not needed for ib_ucm_open()

Remove explicit cycle_kernel_lock() call and document why the code is safe.

Signed-off-by: Roland Dreier <rolandd@cisco.com>
---

diff --git a/drivers/infiniband/core/ucm.c b/drivers/infiniband/core/ucm.c
index 9494005..e603736 100644
--- a/drivers/infiniband/core/ucm.c
+++ b/drivers/infiniband/core/ucm.c
@@ -43,7 +43,6 @@
 #include <linux/cdev.h>
 #include <linux/idr.h>
 #include <linux/mutex.h>
-#include <linux/smp_lock.h>
 
 #include <asm/uaccess.h>
 
@@ -1154,11 +1153,18 @@ static unsigned int ib_ucm_poll(struct file *filp,
 	return mask;
 }
 
+/*
+ * ib_ucm_open() does not need the BKL:
+ *
+ *  - no global state is referred to;
+ *  - there is no ioctl method to race against;
+ *  - no further module initialization is required for open to work
+ *    after the device is registered.
+ */
 static int ib_ucm_open(struct inode *inode, struct file *filp)
 {
 	struct ib_ucm_file *file;
 
-	cycle_kernel_lock();
 	file = kmalloc(sizeof(*file), GFP_KERNEL);
 	if (!file)
 		return -ENOMEM;