How to get pointer of task_struct corresponding to a pid value.

rach_993 · 06-12-2012, 12:45 PM

Hi Guys,

I have written a kernel module code.where I have list of pid (process ids) stored in a Singular link list. I want to know if processes corresponding to its pids is alive or killed.in order to meet this requirement I need pointer of task_struct corresponding to the pid.

Also if any one know about what is namespace in linux OS??

Please help me.

Regards
Rach D

bsat · 06-13-2012, 12:45 AM

Well one method I can think of, not very efficient though, is to loop through all the task_structs comparing the pids. If the processes that you have are related to each other ,that is they have a common parent then it will be easier .

Here is an example of how you can iterate over processes.
http://tuxthink.blogspot.in/2011/03/...roc-entry.html

rach_993 · 06-13-2012, 01:00 AM

Hey

Is it possible if we could travel in task_struct. I have pid but not relevant to any other pid. i have just a value of pid ,can i get pointer of task_struct using that pid value only if yes help me please

Regards

Rach D

rach_993 · 06-13-2012, 05:22 AM

Hi All,

Can any one let me know what that function working and how to use it to get task_struct pointer please help me !!!

Regards
Rach D

micscherer · 06-14-2012, 11:48 AM

find_task_by_pid will return a pointer to a task_struct,
though it is now deprecated, because with namespaces it
will return only the task in an initial namespace.

you can use task_by_pid_ns and pass it the namespace
where your pid resides.

regards, michael

sundialsvcs · 06-26-2012, 12:43 PM

Best thing to do is to find the handler for some function-call, in the source code of your particular distribution, that uses a PID as one of its inputs. Trace through the code to find out how it's used. Copy that example, and of course, "Google it."