Can I get thread ID in user-mode program?

[gprabhunath@gmail.com (Prabhu nath)]

Try this.
syscall(SYS_gettid);

This should return the value of task_struct->pid

Regards,
Prabhu



On Wed, Dec 29, 2010 at 11:00 PM, CP YEH <ntdev74@gmail.com> wrote:

> Hi,
>
> I would like to know if I can obtain thread id of calling thread. Let
> me clarify what I mean by this.
>
> First, here is task_struct from linux kernel code.
>
> struct task_struct {
>       struct list_head tasks;
>       pid_t pid;
>       pid_t tgid;
>       struct task_struct *group_leader;  /* threadgroup leader */
>       struct list_head thread_group;
> };
>
> I understand that getpid returns tgid and gettid via __NR_gettid
> returns tid but according to manpage, it seems to me that it is same
> as what I get from getpid().
>
> Man page of gettid:
>       gettid() returns the thread ID of the current process.  This is
> equal to the
>       process ID (as returned by getpid(2)), unless  the  process  is
>  part  of  a
>       thread  group
>
> However, I would like to obtain pid of task_struct. Is there any way I
> can get that information?
> Thank you.
>
> YEH
>
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