IB/uverbs: Convert *cdev to cdev in struct ib_uverbs_device

Instead of storing a pointer to a cdev, embed the entire struct cdev.

This change allows us to use the container_of() macro in
ib_uverbs_open() in a future patch.

This change increases the size of struct ib_uverbs_device to 168 bytes
across 3 cachelines from 80 bytes in 2 cachelines.  However, we
rearrange the members so that everything fits into the first cacheline
except for the struct cdev. Finally, we don't touch the cdev in any
fastpaths, so this change shouldn't negatively affect performance.

Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

2 files changed, 14 insertions, 16 deletions

diff --git a/drivers/infiniband/core/uverbs.h b/drivers/infiniband/core/uverbs.h
index b3ea9587dc80..e695f65328a3 100644
--- a/drivers/infiniband/core/uverbs.h
+++ b/drivers/infiniband/core/uverbs.h
@@ -41,6 +41,7 @@
 #include <linux/idr.h>
 #include <linux/mutex.h>
 #include <linux/completion.h>
+#include <linux/cdev.h>
 
 #include <rdma/ib_verbs.h>
 #include <rdma/ib_umem.h>
@@ -69,12 +70,12 @@
 
 struct ib_uverbs_device {
         struct kref                             ref;
+        int                                     num_comp_vectors;
         struct completion                       comp;
-        int                                     devnum;
-        struct cdev                            *cdev;
         struct device                          *dev;
         struct ib_device                       *ib_dev;
-        int                                     num_comp_vectors;
+        int                                     devnum;
+        struct cdev                             cdev;
 };
 
 struct ib_uverbs_event_file {
diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
index 5f284ffd430e..5da9a734959a 100644
--- a/drivers/infiniband/core/uverbs_main.c
+++ b/drivers/infiniband/core/uverbs_main.c
@@ -43,7 +43,6 @@
 #include <linux/sched.h>
 #include <linux/file.h>
 #include <linux/mount.h>
-#include <linux/cdev.h>
 
 #include <asm/uaccess.h>
 
@@ -761,17 +760,15 @@ static void ib_uverbs_add_one(struct ib_device *device)
         uverbs_dev->ib_dev           = device;
         uverbs_dev->num_comp_vectors = device->num_comp_vectors;
 
-        uverbs_dev->cdev = cdev_alloc();
-        if (!uverbs_dev->cdev)
-                goto err;
-        uverbs_dev->cdev->owner = THIS_MODULE;
-        uverbs_dev->cdev->ops = device->mmap ? &uverbs_mmap_fops : &uverbs_fops;
-        kobject_set_name(&uverbs_dev->cdev->kobj, "uverbs%d", uverbs_dev->devnum);
-        if (cdev_add(uverbs_dev->cdev, IB_UVERBS_BASE_DEV + uverbs_dev->devnum, 1))
+        cdev_init(&uverbs_dev->cdev, NULL);
+        uverbs_dev->cdev.owner = THIS_MODULE;
+        uverbs_dev->cdev.ops = device->mmap ? &uverbs_mmap_fops : &uverbs_fops;
+        kobject_set_name(&uverbs_dev->cdev.kobj, "uverbs%d", uverbs_dev->devnum);
+        if (cdev_add(&uverbs_dev->cdev, IB_UVERBS_BASE_DEV + uverbs_dev->devnum, 1))
                 goto err_cdev;
 
         uverbs_dev->dev = device_create(uverbs_class, device->dma_device,
-                                        uverbs_dev->cdev->dev, uverbs_dev,
+                                        uverbs_dev->cdev.dev, uverbs_dev,
                                         "uverbs%d", uverbs_dev->devnum);
         if (IS_ERR(uverbs_dev->dev))
                 goto err_cdev;
@@ -790,10 +787,10 @@ static void ib_uverbs_add_one(struct ib_device *device)
         return;
 
 err_class:
-        device_destroy(uverbs_class, uverbs_dev->cdev->dev);
+        device_destroy(uverbs_class, uverbs_dev->cdev.dev);
 
 err_cdev:
-        cdev_del(uverbs_dev->cdev);
+        cdev_del(&uverbs_dev->cdev);
         clear_bit(uverbs_dev->devnum, dev_map);
 
 err:
@@ -811,8 +808,8 @@ static void ib_uverbs_remove_one(struct ib_device *device)
                 return;
 
         dev_set_drvdata(uverbs_dev->dev, NULL);
-        device_destroy(uverbs_class, uverbs_dev->cdev->dev);
-        cdev_del(uverbs_dev->cdev);
+        device_destroy(uverbs_class, uverbs_dev->cdev.dev);
+        cdev_del(&uverbs_dev->cdev);
 
         spin_lock(&map_lock);
         dev_table[uverbs_dev->devnum] = NULL;