tty open call stack

if you want to know tty open call stack.

you can add WARN_ON in low layer function. and it will show as the below:

 

(unwind_backtrace+0x0/0x11c) from [<c0072bf8>] (warn_slowpath_common+0x4c/0x64)
(warn_slowpath_common+0x4c/0x64) from [<c0072c28>] (warn_slowpath_null+0x18/0x1c)
(warn_slowpath_null+0x18/0x1c) from [<c02477e4>] (msm_hs_startup+0x2c/0x4cc)
(msm_hs_startup+0x2c/0x4cc) from [<c0243474>] (uart_port_startup+0x60/0x160)
(uart_port_startup+0x60/0x160) from [<c02440f4>] (uart_open+0xf8/0x184)
(uart_open+0xf8/0x184) from [<c023a1ac>] (tty_open+0x2f0/0x484)
(tty_open+0x2f0/0x484) from [<c0117240>] (chrdev_open+0x118/0x13c)
(chrdev_open+0x118/0x13c) from [<c0111d40>] (__dentry_open.isra.13+0x190/0x29c)
(__dentry_open.isra.13+0x190/0x29c) from [<c011fcb4>] (do_last.isra.31+0x690/0x6c0)
(do_last.isra.31+0x690/0x6c0) from [<c011fea8>] (path_openat+0xb4/0x34c)
(path_openat+0xb4/0x34c) from [<c0120220>] (do_filp_open+0x2c/0x78)
(do_filp_open+0x2c/0x78) from [<c0112a64>] (do_sys_open+0xd8/0x170)
(do_sys_open+0xd8/0x170) from [<c000e280>] (ret_fast_syscall+0x0/0x30)

 

 

(msm_hs_shutdown+0x128/0x320) from [<c024a0b4>] (uart_port_shutdown+0x2c/0x38)
(uart_port_shutdown+0x2c/0x38) from [<c024a498>] (uart_shutdown+0x94/0xc0)
(uart_shutdown+0x94/0xc0) from [<c024bdd8>] (uart_hangup+0x64/0xd4)
(uart_hangup+0x64/0xd4) from [<c0240540>] (__tty_hangup+0x2c4/0x328)
(__tty_hangup+0x2c4/0x328) from [<c02414d0>] (disassociate_ctty+0x74/0x1fc)
(disassociate_ctty+0x74/0x1fc) from [<c0079270>] (do_exit+0x31c/0x7dc)
(do_exit+0x31c/0x7dc) from [<c00799d0>] (do_group_exit+0x88/0xb4)
(do_group_exit+0x88/0xb4) from [<c0079a0c>] (__wake_up_parent+0x0/0x18)