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Move the check for the snp device being already attached after the

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fget() call, that is sleeping point, and possibly dropping Giant.

The snp_target == NULL implies the snp_tty == NULL. Remove the code
that is put under snp_target == NULL and snp_tty != NULL clause.

In snpclose(), do the snp_detach() before scheduling the snp device
destruction. Otherwise, after the return from snpclose(), the snp
device is already removed from the snp_list, but tty is still in
snooped state. Any attempt to do i/o on such tty cause panic because
ttytosnp() returns NULL.

Tested by:	Peter Holm
MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2007-12-24 13:47:16 +00:00
parent 280c5853dd
commit 316d90a37b
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=174888
1 changed files with 6 additions and 11 deletions
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17
sys/dev/snp/snp.c
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@ -466,7 +466,8 @@ snpclose(struct cdev *dev, int flags, int fmt, struct thread *td)
free(snp->snp_buf, M_SNP);
snp->snp_flags &= ~SNOOP_OPEN;
dev->si_drv1 = NULL;
destroy_dev_sched_cb(dev, snp_detach, snp);
snp_detach(snp);
destroy_dev_sched(dev);
return (0);
}
@ -491,7 +492,7 @@ snpioctl(struct cdev *dev, u_long cmd, caddr_t data, int flags,
struct thread *td)
{
struct snoop *snp;
struct tty *tp, *tpo;
struct tty *tp;
struct cdev *tdev;
struct file *fp;
int s;
@ -502,8 +503,6 @@ snpioctl(struct cdev *dev, u_long cmd, caddr_t data, int flags,
s = *(int *)data;
if (s < 0)
return (snp_down(snp));
if (snp->snp_tty != NULL)
return (EBUSY);
if (fget(td, s, &fp) != 0)
return (EINVAL);
@ -516,6 +515,9 @@ snpioctl(struct cdev *dev, u_long cmd, caddr_t data, int flags,
tdev = fp->f_vnode->v_rdev;
fdrop(fp, td);
if (snp->snp_tty != NULL)
return (EBUSY);
tp = snpdevtotty(tdev);
if (!tp)
return (EINVAL);
@ -523,13 +525,6 @@ snpioctl(struct cdev *dev, u_long cmd, caddr_t data, int flags,
return (EBUSY);
s = spltty();
if (snp->snp_target == NULL) {
tpo = snp->snp_tty;
if (tpo)
tpo->t_state &= ~TS_SNOOP;
}
tp->t_state |= TS_SNOOP;
snp->snp_olddisc = tp->t_line;
tp->t_line = snooplinedisc;