kernelHow to read/write files within kernel module?

Posted by Methos on Stack Overflow See other posts from Stack Overflow or by Methos
Published on 2009-07-26T10:59:12Z Indexed on 2010/04/23 20:53 UTC
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linux-kernel

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file-io

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kernel-module

I know all the discussions about why one should not read/write files from kernel, instead how to use /proc or netlink to do that. I want to read/write anyway. I have also read http://www.linuxjournal.com/article/8110

However, problem is 2.6.30 does not export sys_read(). Rather its wrapped in SYSCALL_DEFINE3. So if I use that in my module, I get following warnings: WARNING: "sys_read" [xxx.ko] undefined! WARNING: "sys_open" [xxx.ko] undefined!

Obviously insmod cannot load the module because linking does not happen correctly.

Questions:

How to read/write within kernel after 2.6.22 (where sys_read()/sys_open() are not exported)?
In general, how to use system calls wrapped in macro SYSCALL_DEFINEn() from within the kernel?

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