Dear All, I was trying the following and had a doubt.
From my kernel module I want to iterate over task list and do some sleepy operation for all the process for which my task->flag is set .I know by holding read_lock(tasklist_lock)/rcu_read_lock I should not be performing any sleepy operation. So I have coded like below :
1. Take the read lock 2. Iterate over task (for_each_process) 3. If my flag is set I unlock the tasklist_lock and get_task_struct 4. Perform the sleepy operation 5. Then put_task_struct 6. Again take read_lock(&tasklist_lock); 7. Loop continues The code snippet is as shown below : read_lock(&tasklist_lock); for_each_process(c) { if (c->my_flag) { read_unlock(&tasklist_lock); get_task_struct(c); ... perform_sleepy_operation(); ... put_task_struct(c); read_lock(&tasklist_lock); } } Please let me know if this approach is correct. Thanks and Regards, Pranami