diff mbox

[v3,2/9] IB/core: Replace semaphore sm_sem with an atomic wait

Message ID 1477468874-16328-3-git-send-email-binoy.jayan@linaro.org
State Superseded
Headers show

Commit Message

Binoy Jayan Oct. 26, 2016, 8:01 a.m. UTC 
The semaphore 'sm_sem' is used for an exclusive ownership of the device
so model the same as an atomic variable with an associated wait_event.
Semaphores are going away in the future.

Signed-off-by: Binoy Jayan <binoy.jayan@linaro.org>

---
 drivers/infiniband/core/user_mad.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
diff mbox

Patch

diff --git a/drivers/infiniband/core/user_mad.c b/drivers/infiniband/core/user_mad.c
index 415a318..6101c0a 100644
--- a/drivers/infiniband/core/user_mad.c
+++ b/drivers/infiniband/core/user_mad.c
@@ -67,6 +67,8 @@  enum {
 	IB_UMAD_MINOR_BASE = 0
 };
 
+#define UMAD_F_CLAIM	0x01
+
 /*
  * Our lifetime rules for these structs are the following:
  * device special file is opened, we take a reference on the
@@ -87,7 +89,8 @@  struct ib_umad_port {
 
 	struct cdev           sm_cdev;
 	struct device	      *sm_dev;
-	struct semaphore       sm_sem;
+	wait_queue_head_t     wq;
+	unsigned long         flags;
 
 	struct mutex	       file_mutex;
 	struct list_head       file_list;
@@ -1030,12 +1033,14 @@  static int ib_umad_sm_open(struct inode *inode, struct file *filp)
 	port = container_of(inode->i_cdev, struct ib_umad_port, sm_cdev);
 
 	if (filp->f_flags & O_NONBLOCK) {
-		if (down_trylock(&port->sm_sem)) {
+		if (test_and_set_bit(UMAD_F_CLAIM, &port->flags)) {
 			ret = -EAGAIN;
 			goto fail;
 		}
 	} else {
-		if (down_interruptible(&port->sm_sem)) {
+		if (wait_event_interruptible(port->wq,
+					     !test_and_set_bit(UMAD_F_CLAIM,
+					     &port->flags))) {
 			ret = -ERESTARTSYS;
 			goto fail;
 		}
@@ -1060,7 +1065,8 @@  static int ib_umad_sm_open(struct inode *inode, struct file *filp)
 	ib_modify_port(port->ib_dev, port->port_num, 0, &props);
 
 err_up_sem:
-	up(&port->sm_sem);
+	clear_bit(UMAD_F_CLAIM, &port->flags);
+	wake_up(&port->wq);
 
 fail:
 	return ret;
@@ -1079,7 +1085,8 @@  static int ib_umad_sm_close(struct inode *inode, struct file *filp)
 		ret = ib_modify_port(port->ib_dev, port->port_num, 0, &props);
 	mutex_unlock(&port->file_mutex);
 
-	up(&port->sm_sem);
+	clear_bit(UMAD_F_CLAIM, &port->flags);
+	wake_up(&port->wq);
 
 	kobject_put(&port->umad_dev->kobj);
 
@@ -1177,7 +1184,8 @@  static int ib_umad_init_port(struct ib_device *device, int port_num,
 
 	port->ib_dev   = device;
 	port->port_num = port_num;
-	sema_init(&port->sm_sem, 1);
+	init_waitqueue_head(&port->wq);
+	__clear_bit(UMAD_F_CLAIM, &port->flags);
 	mutex_init(&port->file_mutex);
 	INIT_LIST_HEAD(&port->file_list);