Re: [PATCH v2] CONNECTOR: add a proc entry to list connectors

I got a problem when I wanted to check if the kernel supports process
event connector, and It seems there's no way to do this check.

At best I can check if the kernel supports connector or not, by looking
into /proc/net/netlink, or maybe checking the return value of bind() to
see if it's ENOENT.

So it would be useful to add /proc/net/connector to list all supported
connectors:
 # cat /proc/net/connector
 Name            ID
 connector       4294967295:4294967295
 cn_proc         1:1
 w1              3:1

Changelog:
- fix memory leak: s/seq_release/single_release
- use spin_lock_bh instead of spin_lock_irqsave

Signed-off-by: Li Zefan <redacted>
Acked-by: Evgeniy Polyakov <redacted>
---
 drivers/connector/connector.c |   40
++++++++++++++++++++++++++++++++++++++++
 1 files changed, 40 insertions(+), 0 deletions(-)

diff --git a/drivers/connector/connector.c b/drivers/connector/connector.c
index 85e2ba7..bf48300 100644
--- a/drivers/connector/connector.c
+++ b/drivers/connector/connector.c

@@ -27,6 +27,8 @@
 #include <linux/moduleparam.h>
 #include <linux/connector.h>
 #include <linux/mutex.h>
+#include <linux/proc_fs.h>
+#include <linux/spinlock.h>

 #include <net/sock.h>

@@ -403,6 +405,40 @@ static void cn_callback(void *data)
       mutex_unlock(&notify_lock);
 }

+static int cn_proc_show(struct seq_file *m, void *v)
+{
+       struct cn_queue_dev *dev = cdev.cbdev;
+       struct cn_callback_entry *cbq;
+
+       seq_printf(m, "Name            ID\n");
+
+       spin_lock_bh(&dev->queue_lock);
+
+       list_for_each_entry(cbq, &dev->queue_list, callback_entry) {
+               seq_printf(m, "%-15s %u:%u\n",
+                          cbq->id.name,
+                          cbq->id.id.idx,
+                          cbq->id.id.val);
+       }
+
+       spin_unlock_bh(&dev->queue_lock);
+
+       return 0;
+}
+
+static int cn_proc_open(struct inode *inode, struct file *file)
+{
+       return single_open(file, cn_proc_show, NULL);
+}
+
+static const struct file_operations cn_file_ops = {
+       .owner   = THIS_MODULE,
+       .open    = cn_proc_open,
+       .read    = seq_read,
+       .llseek  = seq_lseek,
+       .release = single_release
+};
+
 static int __devinit cn_init(void)
 {
       struct cn_dev *dev = &cdev;

@@ -434,6 +470,8 @@ static int __devinit cn_init(void)
               return -EINVAL;
       }

+       proc_net_fops_create(&init_net, "connector", S_IRUGO,

&cn_file_ops);
+
       return 0;
 }

@@ -443,6 +481,8 @@ static void __devexit cn_fini(void)

       cn_already_initialized = 0;

+       proc_net_remove(&init_net, "connector");
+
       cn_del_callback(&dev->id);
       cn_queue_free_dev(dev->cbdev);
       netlink_kernel_release(dev->nls);
--

1.5.4.rc3
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