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Subject[PATCH v2 09/18] IB/umad: remove port_table[]
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We no longer need this data structure, as it was used to associate
an inode back to a struct ib_umad_port during ->open().

But now that we're embedding a struct cdev in struct ib_umad_port,
we can use the container_of() macro to go from the inode back to
the device instead.

Signed-off-by: Alex Chiang <achiang@hp.com>
---
drivers/infiniband/core/user_mad.c | 45 +++++++-----------------------------
1 files changed, 9 insertions(+), 36 deletions(-)
diff --git a/drivers/infiniband/core/user_mad.c b/drivers/infiniband/core/user_mad.c
index 40440ef..46c8879 100644
--- a/drivers/infiniband/core/user_mad.c
+++ b/drivers/infiniband/core/user_mad.c
@@ -65,12 +65,9 @@ enum {
};

/*
- * Our lifetime rules for these structs are the following: each time a
- * device special file is opened, we look up the corresponding struct
- * ib_umad_port by minor in the umad_port[] table while holding the
- * port_lock. If this lookup succeeds, we take a reference on the
- * ib_umad_port's struct ib_umad_device while still holding the
- * port_lock; if the lookup fails, we fail the open(). We drop these
+ * Our lifetime rules for these structs are the following:
+ * device special file is opened, we take a reference on the
+ * ib_umad_port's struct ib_umad_device. We drop these
* references in the corresponding close().
*
* In addition to references coming from open character devices, there
@@ -78,12 +75,7 @@ enum {
* module's reference taken when allocating the ib_umad_device in
* ib_umad_add_one().
*
- * When destroying an ib_umad_device, we clear all of its
- * ib_umad_ports from umad_port[] while holding port_lock before
- * dropping the module's reference to the ib_umad_device. This is
- * always safe because any open() calls will either succeed and obtain
- * a reference before we clear the umad_port[] entries, or fail after
- * we clear the umad_port[] entries.
+ * When destroying an ib_umad_device, we drop the module's reference.
*/

struct ib_umad_port {
@@ -136,7 +128,6 @@ static struct class *umad_class;
static const dev_t base_dev = MKDEV(IB_UMAD_MAJOR, IB_UMAD_MINOR_BASE);

static DEFINE_SPINLOCK(port_lock);
-static struct ib_umad_port *umad_port[IB_UMAD_MAX_PORTS];
static DECLARE_BITMAP(dev_map, IB_UMAD_MAX_PORTS);

static void ib_umad_add_one(struct ib_device *device);
@@ -779,15 +770,11 @@ static long ib_umad_compat_ioctl(struct file *filp, unsigned int cmd,
/*
* ib_umad_open() does not need the BKL:
*
- * - umad_port[] accesses are protected by port_lock, the
- * ib_umad_port structures are properly reference counted, and
+ * - the ib_umad_port structures are properly reference counted, and
* everything else is purely local to the file being created, so
* races against other open calls are not a problem;
* - the ioctl method does not affect any global state outside of the
* file structure being operated on;
- * - the port is added to umad_port[] as the last part of module
- * initialization so the open method will either immediately run
- * -ENXIO, or all required initialization will be done.
*/
static int ib_umad_open(struct inode *inode, struct file *filp)
{
@@ -795,13 +782,10 @@ static int ib_umad_open(struct inode *inode, struct file *filp)
struct ib_umad_file *file;
int ret = 0;

- spin_lock(&port_lock);
- port = umad_port[iminor(inode) - IB_UMAD_MINOR_BASE];
+ port = container_of(inode->i_cdev, struct ib_umad_port, cdev);
if (port)
kref_get(&port->umad_dev->ref);
- spin_unlock(&port_lock);
-
- if (!port)
+ else
return -ENXIO;

mutex_lock(&port->file_mutex);
@@ -892,13 +876,10 @@ static int ib_umad_sm_open(struct inode *inode, struct file *filp)
};
int ret;

- spin_lock(&port_lock);
- port = umad_port[iminor(inode) - IB_UMAD_MINOR_BASE - IB_UMAD_MAX_PORTS];
+ port = container_of(inode->i_cdev, struct ib_umad_port, sm_cdev);
if (port)
kref_get(&port->umad_dev->ref);
- spin_unlock(&port_lock);
-
- if (!port)
+ else
return -ENXIO;

if (filp->f_flags & O_NONBLOCK) {
@@ -1042,10 +1023,6 @@ static int ib_umad_init_port(struct ib_device *device, int port_num,
if (device_create_file(port->sm_dev, &dev_attr_port))
goto err_sm_dev;

- spin_lock(&port_lock);
- umad_port[port->dev_num] = port;
- spin_unlock(&port_lock);
-
return 0;

err_sm_dev:
@@ -1079,10 +1056,6 @@ static void ib_umad_kill_port(struct ib_umad_port *port)
cdev_del(&port->cdev);
cdev_del(&port->sm_cdev);

- spin_lock(&port_lock);
- umad_port[port->dev_num] = NULL;
- spin_unlock(&port_lock);
-
mutex_lock(&port->file_mutex);

port->ib_dev = NULL;


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