Hi all,
i have written a kernel module while modifies the sys_call_table and inserts
new syscalls to bring some performance counters to the userland.
I m stuck in bringing process counters.
The idea behind it is, instead of reading /proc/<pid>/ for data
we decided to bring the data down to the userland from the kernel through our
system call.
This is what my assumption is:
the process information is stored in a link list of struct task_struct.
If i can copy the contents of the link list to the user memory
using the macro for_each_task(p) defined in linux/sched.h
for_each_task (p) {
/*do copy and all that stuff*/
}
i can read the appropriate values from that copied link list from that
userland program.
Now my questions are:
i have used copy_to_user to copy a structure to the userland program
but i donno how to copy a link list.
initially i thought of allocating memory in the module and copy the original
contents to the memory and give it to useprogram.but i donno whether it is
possible to allocate userland memory from kernel or not.
Is there any other decent way of doing it.
pls clarify if i my understanding is wrong.
thanks and regards,
mohan.
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