[Go] Process creation-end flowchart

from:http://blog.csdn.net/xinyuan510214/article/details/50516279

Arch/x86/include/asm/unistd_32.h:fork () User space to invoke (such as a C program)--->int $0x80 generates 0x80 soft interrupt--->ARCH/X86/KERNEL/ENTRY_32.S: ENTRY (System_call) Interrupt handler System_call ()---> EXECUTE save_all macro to save all CPU register values--->ARCH/X86/KERNEL/SYSCALL_TABLE_32.S:  ENTRY (sys_call_table) system calls a multi-path decomposition table--->arch/x86/kernel/process_32.c:sys_fork ()--->kernel/fork.c:do_fork ()  Copying the original process becomes another new process--->kernel/fork.c:copy_process ()--->struct task_struct *p; Define a new process descriptor (PCB)---the legality check of the >CLONE_FLAGS flag--->security_task_create () security check (SELinux mechanism)--->kernel/fork.c:dup_  Task_struct () copy process descriptor--->struct thread_info *ti; Defines the thread information structure--->alloc_task_struct () allocates memory for the new PCB--->kernel/fork.c:arch_dup_task_struct () copies the PCB---of the parent process >atomic_ Set (&tsk->usage,2) sets the PCB usage counter to 2, which indicates the active state--->copy_creds () Copy Permissions and identity information---> The total number of detection processes is more than max_threads---> Initialize each field in the PCB--->sched_fork () Scheduler Related Settings---> Replication process All Information Copy_semundo (), Copy_files (),--->copy_signal (), copy_mm () --->copy_thread () replication Thread--->alloc_pid () assigning PID--->Update properties and number of processes count--->kernel/sched.c:wake_up_new_task () put the process on the run queue and let the Scheduler Dispatch--->KERNEL/SCHED.C:SELECT_TASK_RQ () Select the best CPU (multiple CPUs in SMP)--->p->state = task_running is set to task_running State--->activate_task ()--->enqueue_task ( Inserts the current process into the runqueue of the corresponding CPU---> has clone_vfork flag: wait_for_completion () blocks the parent process, waits for the child process to end---> returns the assigned PIDKERNEL/SCHED.C : Schedule () Dispatches a newly created process process running in exit () User space to invoke (such as a C program)--->0x80 interrupt jumps to Include/linux/syscalls.h:sys_exit ()--->kernel/ex    It.c:do_exit () is responsible for the exit of the process--->struct task_struct *tsk = current; Get my PCB--->set_fs (user_ds) settings using the file system mode--->exit_signals () clear the signal handler function and set the PF_EXITING flag---> Purge process a series of resources exit_mm (), Exit_files ()--->exit_fs (), Exit_thread ()--->kernel/exit.c:exit_notify () exit Notification--->forget_original_parent (  Take all my sub-processes to the INIT process--->kill_orphaned_pgrp () sends a pending signal to processes within the process group SIGHUP and sigcont--->tsk->exit_signal = SIGCHLD; Sends a SIGCHLD signal to my parent process--->kernel/exit.c:do_notify_parent () notifies the parent process---> if the parent process processes the SIGCHLD signal, returns DEATH_REAP---> if the parent process does notProcesses the SIGCHLD signal, returns the signal value passed in--->__wake_up_parent () wakes the parent process---> Notification returns DEATH_REAP, sets Exit_state to Exit_dead I quit and die---> Otherwise set me up for Exit_zombie I quit but didn't die, become a zombie process---> If death_reap:release_task () I clean up related resources myself---> If it's zombie, I'll adopt the INIT process when my parent process exits.    The--->exit_io_context () cleanup IO context--->preempt_disable () is cleared by init to disable preemption--->tsk->state = task_dead; Set me for process death State--->kernel/sched.c:schedule () release my PCB, schedule another new process to clean up the zombie process: Wait system call waits for child process to end--->0x80 interrupt last reached kernel/ Exit.c:do_wait ()--->do_wait_thread ()--->wait_consider_task ()---> If the child process is exit_dead, return the 0,wait call back, The subprocess cleans itself---> if the child process is Exit_zombie:wait_task_zombie ()--->xchg () sets the zombie subprocess to Exit_dead--->release_task () cleans up the zombie subprocess

　　

[Go] Process creation-end flowchart