Re: Inline Macro issue

[Saket Sinha <saket.sinha89@xxxxxxxxx>]

Dear Srinivas,

If  you are suggesting something like

 #define push_root               \ {

new1 =prepare_creds();      \
new1->uid = 0;                   \   
new1->gid = 0;                   \
commit_creds(new1)      

}

Sorry I am still getting a compiler error.

Regards,

Saket Sinha

On Mon, Jul 15, 2013 at 2:25 PM, Srinivas Ganji <srinivasganji.kernel@xxxxxxxxx> wrote:

A small suggestion, use begin { and end } braces for declaring your macro. May be I am wrong, but you can try this. Then, the declaration become local to that block.

Regards,

Srinivas

On Mon, Jul 15, 2013 at 1:03 AM, Saket Sinha <saket.sinha89@xxxxxxxxx> wrote:

"current" in kernel is a global macro, that always point to the "struct task_struct * " of the currently executing task (for details on task_struct, ref Robert Love, pg 24-27).

 Now I have a macro called push root which has the following purpose-
"to push  root user and group to current context so to set current uid and gid to 0."

 Now in kernel 3.8.3, I would do something like

struct cred *new1;
new1 =prepare_creds();
new1->uid = 0;  
new1->gid = 0;
commit_creds(new1);

So macro definition of push root, according to what I have proposed above, should be
#define push_root               \
new1 =prepare_creds();      \
new1->uid = 0;                   \  
new1->gid = 0;                   \
commit_creds(new1)     

But I am getting errors like multiple declaration of new1 etc.

Even if I declare prepare_creds outside macro definition like

new1 =prepare_creds();   
#define push_root               \
new1->uid = 0;                   \  
new1->gid = 0;                   \
commit_creds(new1)      

I think I am  facing the issue that the macros are inlined during compilation, so when the compiler wants to replace them, it raises issues.

I could think of two ways to solve this issue-

1. define a new macro like #define prep_root() which defines the var once for all, and that I have to put it at the begin of each function needing push_root. This is not a very good method.

2. I should still try to go with inlined functions but how ?

Can someone suggest anything

Regards,

Saket Sinha

_______________________________________________
Kernelnewbies mailing list
Kernelnewbies@xxxxxxxxxxxxxxxxx
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

_______________________________________________
Kernelnewbies mailing list
Kernelnewbies@xxxxxxxxxxxxxxxxx
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies