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According to the comment in struct tty, t_modem is optional; hence we should

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guard against NULL t_modem entry. Otherwise, driver doesn't have t_modem
callback implemented(such like sys/dev/usb/ucycom.c) would panic when
someone opens the driver's associated tty device.

Reviewed by:	phk, sam (mentor)
This commit is contained in:
Tai-hwa Liang 2005-04-13 13:56:17 +00:00
parent 365971ecad
commit 2d4420789d
1 changed files with 4 additions and 2 deletions
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6
sys/kern/tty.c
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@ -3134,7 +3134,8 @@ ttyopen(struct cdev *dev, int flag, int mode, struct thread *td)
*/
tp->t_termios = ISCALLOUT(dev) ? tp->t_init_out : tp->t_init_in;
tp->t_cflag = tp->t_termios.c_cflag;
tp->t_modem(tp, SER_DTR | SER_RTS, 0);
if (tp->t_modem != NULL)
tp->t_modem(tp, SER_DTR | SER_RTS, 0);
++tp->t_wopeners;
error = tp->t_param(tp, &tp->t_termios);
--tp->t_wopeners;
@ -3142,7 +3143,8 @@ ttyopen(struct cdev *dev, int flag, int mode, struct thread *td)
error = tp->t_open(tp, dev);
if (error != 0)
goto out;
if (ISCALLOUT(dev) || (tp->t_modem(tp, 0, 0) & SER_DCD))
if (ISCALLOUT(dev) || (tp->t_modem != NULL &&
(tp->t_modem(tp, 0, 0) & SER_DCD)))
ttyld_modem(tp, 1);
}
/*