A question about proc file system

A question about proc file system

[Yangbin (Robin)]

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Hi all:

	I write a kernel module which make a dir and create a file in proc file system. 
I use proc_mkdir() and create_proc_entry() in init and use remove_proc_entry() in exit.
Now I got a problem during my test:
1. open terminal A, insmod and cd into the dir the module created in proc
2. open terminal B. rmmod and insmod angain.
Then I cannot see the file which should be created by the module, unless terminal A quit the dir.

This will be ok with regale file system like ext3, one teminal's operation will not affert others.
Is this a bug or not?

Regards
Robin
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Re: A question about proc file system

[Alan Cox]

On Wed, 28 Nov 2012 02:55:30 +0000
"Yangbin (Robin)" <robin.yb@huawei.com> wrote:

> Hi all:
> 
> 	I write a kernel module which make a dir and create a file in proc file system. 
> I use proc_mkdir() and create_proc_entry() in init and use remove_proc_entry() in exit.
> Now I got a problem during my test:
> 1. open terminal A, insmod and cd into the dir the module created in proc
> 2. open terminal B. rmmod and insmod angain.
> Then I cannot see the file which should be created by the module, unless terminal A quit the dir.
> 
> This will be ok with regale file system like ext3, one teminal's operation will not affert others.
> Is this a bug or not?

It's not. You are doing the same as this


	mkdir /tmp/example
	cd /tmp/example
	rmdir /tmp/example

	mkdir /tmp/example

in Unix like systems the file handles and current directory references
apply to the object itself not to the path.

When yo reload the driver you create a new and different directory that
has the same name but is not the same thing.