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tuntap(4): use cdevpriv w/ dtor for last close instead of d_close

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cdevpriv dtors will be called when the reference count on the associated
struct file drops to 0, while d_close can be unreliable for cleaning up
state at "last close" for a number of reasons. As far as tunclose/tundtor is
concerned the difference is minimal, so make the switch.
This commit is contained in:
Kyle Evans 2019-10-20 22:55:47 +00:00
parent 6869d530c7
commit 6025077704
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=353786
1 changed files with 16 additions and 11 deletions
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27
sys/net/if_tuntap.c
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@ -220,6 +220,7 @@ static int tuntap_name2info(const char *name, int *unit, int *flags);
static void tunclone(void *arg, struct ucred *cred, char *name,
int namelen, struct cdev **dev);
static void tuncreate(struct cdev *dev);
static void tundtor(void *data);
static void tunrename(void *arg, struct ifnet *ifp);
static int tunifioctl(struct ifnet *, u_long, caddr_t);
static void tuninit(struct ifnet *);
@ -238,7 +239,6 @@ static int tun_clone_destroy(struct if_clone *, struct ifnet *);
static void tun_vnethdr_set(struct ifnet *ifp, int vhdrlen);
static d_open_t tunopen;
static d_close_t tunclose;
static d_read_t tunread;
static d_write_t tunwrite;
static d_ioctl_t tunioctl;
@ -278,7 +278,6 @@ static struct tuntap_driver {
.d_version = D_VERSION,
.d_flags = D_NEEDMINOR,
.d_open = tunopen,
.d_close = tunclose,
.d_read = tunread,
.d_write = tunwrite,
.d_ioctl = tunioctl,
@ -296,7 +295,6 @@ static struct tuntap_driver {
.d_version = D_VERSION,
.d_flags = D_NEEDMINOR,
.d_open = tunopen,
.d_close = tunclose,
.d_read = tunread,
.d_write = tunwrite,
.d_ioctl = tunioctl,
@ -314,7 +312,6 @@ static struct tuntap_driver {
.d_version = D_VERSION,
.d_flags = D_NEEDMINOR,
.d_open = tunopen,
.d_close = tunclose,
.d_read = tunread,
.d_write = tunwrite,
.d_ioctl = tunioctl,
@ -1100,24 +1097,33 @@ tunopen(struct cdev *dev, int flag, int mode, struct thread *td)
if_link_state_change(ifp, LINK_STATE_UP);
TUNDEBUG(ifp, "open\n");
TUN_UNLOCK(tp);
/*
* This can fail with either ENOENT or EBUSY. This is in the middle of
* d_open, so ENOENT should not be possible. EBUSY is possible, but
* the only cdevpriv dtor being set will be tundtor and the softc being
* passed is constant for a given cdev. We ignore the possible error
* because of this as either "unlikely" or "not actually a problem."
*/
(void)devfs_set_cdevpriv(tp, tundtor);
CURVNET_RESTORE();
return (0);
}
/*
* tunclose - close the device - mark i/f down & delete
* tundtor - tear down the device - mark i/f down & delete
* routing info
*/
static int
tunclose(struct cdev *dev, int foo, int bar, struct thread *td)
static void
tundtor(void *data)
{
struct proc *p;
struct tuntap_softc *tp;
struct ifnet *ifp;
bool l2tun;
p = td->td_proc;
tp = dev->si_drv1;
tp = data;
p = curproc;
ifp = TUN2IFP(tp);
TUN_LOCK(tp);
@ -1133,7 +1139,7 @@ tunclose(struct cdev *dev, int foo, int bar, struct thread *td)
if (p->p_pid != tp->tun_pid) {
log(LOG_INFO,
"pid %d (%s), %s: tun/tap protocol violation, non-controlling process closed last.\n",
p->p_pid, p->p_comm, dev->si_name);
p->p_pid, p->p_comm, tp->tun_dev->si_name);
}
/*
@ -1193,7 +1199,6 @@ tunclose(struct cdev *dev, int foo, int bar, struct thread *td)
tun_unbusy_locked(tp);
TUN_UNLOCK(tp);
return (0);
}
static void