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Subject[PATCH] RDMA/ucma: BKL is not needed for ucma_open()
Date
Remove explicit lock_kernel() calls and document why the code is safe.

Signed-off-by: Roland Dreier <rolandd@cisco.com>
---
I'll merge this through my tree unless someone sees something wrong with it...

drivers/infiniband/core/ucma.c | 11 ++++++++---
1 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
index 195f973..b41dd26 100644
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -38,7 +38,6 @@
#include <linux/in.h>
#include <linux/in6.h>
#include <linux/miscdevice.h>
-#include <linux/smp_lock.h>

#include <rdma/rdma_user_cm.h>
#include <rdma/ib_marshall.h>
@@ -1149,6 +1148,14 @@ static unsigned int ucma_poll(struct file *filp, struct poll_table_struct *wait)
return mask;
}

+/*
+ * ucma_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 ucma_open(struct inode *inode, struct file *filp)
{
struct ucma_file *file;
@@ -1157,7 +1164,6 @@ static int ucma_open(struct inode *inode, struct file *filp)
if (!file)
return -ENOMEM;

- lock_kernel();
INIT_LIST_HEAD(&file->event_list);
INIT_LIST_HEAD(&file->ctx_list);
init_waitqueue_head(&file->poll_wait);
@@ -1165,7 +1171,6 @@ static int ucma_open(struct inode *inode, struct file *filp)

filp->private_data = file;
file->filp = filp;
- unlock_kernel();
return 0;
}

--
1.5.6.2


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