#define SYSCALL_DEFINE0(name) asmlinkage long sys_##name(void)
#define SYSCALL_DEFINE1(name, ...) SYSCALL_DEFINEx(1, _##name, __VA_ARGS__)
#define SYSCALL_DEFINE2(name, ...) SYSCALL_DEFINEx(2, _##name, __VA_ARGS__)
#define SYSCALL_DEFINE3(name, ...) SYSCALL_DEFINEx(3, _##name, __VA_ARGS__)
#define SYSCALL_DEFINE4(name, ...) SYSCALL_DEFINEx(4, _##name, __VA_ARGS__)
#define SYSCALL_DEFINE5(name, ...) SYSCALL_DEFINEx(5, _##name, __VA_ARGS__)
#define SYSCALL_DEFINE6(name, ...) SYSCALL_DEFINEx(6, _##name, __VA_ARGS__)
--->
#define SYSCALL_DEFINEx(x, sname, ...) __SYSCALL_DEFINEx(x, sname, __VA_ARGS__)
--->
asmlinkage long sys##name(__SC_DECL##x(__VA_ARGS__))
(1)、open系统调用
open(); --->
/*/fs/open.c*/
SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, int, mode);--->
do_sys_open(); --->
fd = get_unused_fd_flags();//分配FD
do_filp_open(); --->
/*普通文件*/--> __open_namei_create();---> //这里打开文件
vfs_create(); --->
dir->i_op->create(dir, dentry, mode, nd);
/*驱动文件*/--> filp = nameidata_to_filp(&nd, open_flag);--->//这里打开驱动文件
__dentry_open(); --->
//如果没有提供open回调函数，并且驱动中有open接口
//那么就调用驱动的open()函数
open = f->f_op->open;
(2)、write系统调用
write(); --->
//fs/read_write.c
SYSCALL_DEFINE3(write, unsigned int, fd, const char __user *, buf,size_t, count);--->
vfs_write(file, buf, count, &pos);--->
if (file->f_op->write)
ret = file->f_op->write(file, buf, count, pos); //调用实现的write函数
else
do_sync_write();--->
ret = filp->f_op->aio_write(&kiocb, &iov, 1, kiocb.ki_pos);//异步写
(3)、read系统调用
read(); --->
SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count); --->
vfs_read(); --->
if (file->f_op->read)
ret = file->f_op->read(file, buf, count, pos);//这里调用read函数
else
ret = do_sync_read(file, buf, count, pos);//异步读
(4)、poll系统调用
poll() --->
//fs/select.c
SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, unsigned int, nfds,long, timeout_msecs);--->
do_sys_poll(); --->
do_poll(); --->
do_pollfd(); --->
file->f_op->poll(file, pwait); //驱动程序里实现的poll函数
poll_schedule_timeout(wait, TASK_INTERRUPTIBLE, to, slack);//真正进入睡眠
(5)、select系统调用
select(); --->
SYSCALL_DEFINE5(select,..........);--->
core_sys_select(); --->
do_select(); --->
poll_initwait(&table);
for(;;){
mask = (*f_op->poll)(file, wait); //调用poll函数
....
poll_schedule_timeout();//真正进入睡眠
}
poll_freewait(&table);
(6)、ioctl系统调用
ioctl(); --->
//fs/ioctl.c
SYSCALL_DEFINE3(ioctl, unsigned int, fd, unsigned int, cmd, unsigned long, arg);--->
do_vfs_ioctl();--->
vfs_ioctl(filp, cmd, arg); --->
if (filp->f_op->unlocked_ioctl)
filp->f_op->unlocked_ioctl(filp, cmd, arg);
else if (filp->f_op->ioctl)
filp->f_op->ioctl(filp->f_path.dentry->d_inode,filp, cmd, arg);
(7)、mmap系统调用
mmap(); --->
//arch/powerpc/kernel/syscall.c
sys_mmap(); --->
do_mmap2();--->
do_mmap_pgoff();--->
mmap_region();--->
file->f_op->mmap(file, vma);
(6)、close系统调用
close(); --->
//fs/open.c
SYSCALL_DEFINE1(close, unsigned int, fd);--->
filp_close(filp, files);--->
if (filp->f_op && filp->f_op->flush)
filp->f_op->flush(filp, id);
