Re: use of basic C syntax with kernel

[Anuz Pratap Singh Tomar <chambilkethakur@xxxxxxxxx>]

On Wed, Sep 8, 2010 at 11:59 AM, Bond <jamesbond.2k.g@xxxxxxxxx> wrote:

Hi,

I am not clear with some C syntax.

I looked at a file 

fs.h

there I have 2-3 doubts

1) A variable NR_OPEN is used what is this used for?

2) const struct iovec *iov; 

  What is the meaning of const before struct here.

const means it is stored in readonly memory and hence an indication, that it cannot be modified once it is assigned some value.
Please read any C book to understand that(recommendations KnR)

3) Some places in the comments I see atomic operations.

What is that?

atomic operations are to be performed in a single go i.e. they are kind of locking mechanism. read LDD by Rubini,corbet and G K-H
 

4) blkcnt_t,loff_t,seqcount,spinlock,__u32    are defined in structure inode.

these are data types, you need to see Robert love's book LKD

Suggestion: read more before you ask all this, i think even googling around will answer some of these queries.