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Added D_TRACKCLOSE to sndstat_cdevsw to fix the situation when

Browse Source 
another process is in open() or stat() for the device node, then
close() from the owning process does not result in cdevsw close
method call. This fixes the pemanent "Device busy" seen.

Changed the sndstat_lock from mutex to sx.  This allows to extend
the region covered by the lock, to include the uiomove() call in
sndstat_read() and bufptr increment. This fixes the "panic:
sbuf_put_byte called with finished or corrupt sbuf" seen.

In collaboration with:	kib
MFC after:	1 week
This commit is contained in:
Peter Holm 2012-05-02 19:32:11 +00:00
parent f5fbd56ca7
commit 85f6230a1d
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=234932
1 changed files with 37 additions and 42 deletions
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79
sys/dev/sound/pcm/sndstat.c
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@ -53,6 +53,7 @@ static struct cdevsw sndstat_cdevsw = {
.d_close = sndstat_close,
.d_read = sndstat_read,
.d_name = "sndstat",
.d_flags = D_TRACKCLOSE,
};
struct sndstat_entry {
@ -63,7 +64,7 @@ struct sndstat_entry {
int type, unit;
};
static struct mtx sndstat_lock;
static struct sx sndstat_lock;
static struct sbuf sndstat_sbuf;
static struct cdev *sndstat_dev = NULL;
static int sndstat_bufptr = -1;
@ -93,16 +94,14 @@ sysctl_hw_snd_sndstat_pid(SYSCTL_HANDLER_ARGS)
if (sndstat_dev == NULL)
return (EINVAL);
mtx_lock(&sndstat_lock);
sx_xlock(&sndstat_lock);
val = (int)SNDSTAT_PID(sndstat_dev);
mtx_unlock(&sndstat_lock);
err = sysctl_handle_int(oidp, &val, 0, req);
if (err == 0 && req->newptr != NULL && val == 0) {
mtx_lock(&sndstat_lock);
SNDSTAT_FLUSH();
SNDSTAT_PID_SET(sndstat_dev, 0);
mtx_unlock(&sndstat_lock);
}
sx_unlock(&sndstat_lock);
return (err);
}
SYSCTL_PROC(_hw_snd, OID_AUTO, sndstat_pid, CTLTYPE_INT | CTLFLAG_RW,
@ -119,12 +118,10 @@ sysctl_hw_sndverbose(SYSCTL_HANDLER_ARGS)
verbose = snd_verbose;
error = sysctl_handle_int(oidp, &verbose, 0, req);
if (error == 0 && req->newptr != NULL) {
mtx_lock(&sndstat_lock);
if (verbose < 0 || verbose > 4)
error = EINVAL;
else
snd_verbose = verbose;
mtx_unlock(&sndstat_lock);
}
return error;
}
@ -137,20 +134,19 @@ sndstat_open(struct cdev *i_dev, int flags, int mode, struct thread *td)
if (sndstat_dev == NULL || i_dev != sndstat_dev)
return EBADF;
mtx_lock(&sndstat_lock);
sx_xlock(&sndstat_lock);
if (SNDSTAT_PID(i_dev) != 0) {
mtx_unlock(&sndstat_lock);
sx_unlock(&sndstat_lock);
return EBUSY;
}
SNDSTAT_PID_SET(i_dev, td->td_proc->p_pid);
mtx_unlock(&sndstat_lock);
if (sbuf_new(&sndstat_sbuf, NULL, 4096, SBUF_AUTOEXTEND) == NULL) {
mtx_lock(&sndstat_lock);
SNDSTAT_PID_SET(i_dev, 0);
mtx_unlock(&sndstat_lock);
sx_unlock(&sndstat_lock);
return ENXIO;
}
sndstat_bufptr = 0;
sx_unlock(&sndstat_lock);
return 0;
}
@ -160,16 +156,16 @@ sndstat_close(struct cdev *i_dev, int flags, int mode, struct thread *td)
if (sndstat_dev == NULL || i_dev != sndstat_dev)
return EBADF;
mtx_lock(&sndstat_lock);
sx_xlock(&sndstat_lock);
if (SNDSTAT_PID(i_dev) == 0) {
mtx_unlock(&sndstat_lock);
sx_unlock(&sndstat_lock);
return EBADF;
}
SNDSTAT_FLUSH();
SNDSTAT_PID_SET(i_dev, 0);
mtx_unlock(&sndstat_lock);
sx_unlock(&sndstat_lock);
return 0;
}
@ -182,20 +178,18 @@ sndstat_read(struct cdev *i_dev, struct uio *buf, int flag)
if (sndstat_dev == NULL || i_dev != sndstat_dev)
return EBADF;
mtx_lock(&sndstat_lock);
sx_xlock(&sndstat_lock);
if (SNDSTAT_PID(i_dev) != buf->uio_td->td_proc->p_pid ||
sndstat_bufptr == -1) {
mtx_unlock(&sndstat_lock);
sx_unlock(&sndstat_lock);
return EBADF;
}
mtx_unlock(&sndstat_lock);
if (sndstat_bufptr == 0) {
err = (sndstat_prepare(&sndstat_sbuf) > 0) ? 0 : ENOMEM;
if (err) {
mtx_lock(&sndstat_lock);
SNDSTAT_FLUSH();
mtx_unlock(&sndstat_lock);
sx_unlock(&sndstat_lock);
return err;
}
}
@ -203,6 +197,7 @@ sndstat_read(struct cdev *i_dev, struct uio *buf, int flag)
l = min(buf->uio_resid, sbuf_len(&sndstat_sbuf) - sndstat_bufptr);
err = (l > 0)? uiomove(sbuf_data(&sndstat_sbuf) + sndstat_bufptr, l, buf) : 0;
sndstat_bufptr += l;
sx_unlock(&sndstat_lock);
return err;
}
@ -228,13 +223,13 @@ sndstat_acquire(struct thread *td)
if (sndstat_dev == NULL)
return EBADF;
mtx_lock(&sndstat_lock);
sx_xlock(&sndstat_lock);
if (SNDSTAT_PID(sndstat_dev) != 0) {
mtx_unlock(&sndstat_lock);
sx_unlock(&sndstat_lock);
return EBUSY;
}
SNDSTAT_PID_SET(sndstat_dev, td->td_proc->p_pid);
mtx_unlock(&sndstat_lock);
sx_unlock(&sndstat_lock);
return 0;
}
@ -244,13 +239,13 @@ sndstat_release(struct thread *td)
if (sndstat_dev == NULL)
return EBADF;
mtx_lock(&sndstat_lock);
sx_xlock(&sndstat_lock);
if (SNDSTAT_PID(sndstat_dev) != td->td_proc->p_pid) {
mtx_unlock(&sndstat_lock);
sx_unlock(&sndstat_lock);
return EBADF;
}
SNDSTAT_PID_SET(sndstat_dev, 0);
mtx_unlock(&sndstat_lock);
sx_unlock(&sndstat_lock);
return 0;
}
@ -284,12 +279,12 @@ sndstat_register(device_t dev, char *str, sndstat_handler handler)
ent->unit = unit;
ent->handler = handler;
mtx_lock(&sndstat_lock);
sx_xlock(&sndstat_lock);
SLIST_INSERT_HEAD(&sndstat_devlist, ent, link);
if (type == SS_TYPE_MODULE)
sndstat_files++;
sndstat_maxunit = (unit > sndstat_maxunit)? unit : sndstat_maxunit;
mtx_unlock(&sndstat_lock);
sx_unlock(&sndstat_lock);
return 0;
}
@ -305,17 +300,17 @@ sndstat_unregister(device_t dev)
{
struct sndstat_entry *ent;
mtx_lock(&sndstat_lock);
sx_xlock(&sndstat_lock);
SLIST_FOREACH(ent, &sndstat_devlist, link) {
if (ent->dev == dev) {
SLIST_REMOVE(&sndstat_devlist, ent, sndstat_entry, link);
mtx_unlock(&sndstat_lock);
sx_unlock(&sndstat_lock);
free(ent, M_DEVBUF);
return 0;
}
}
mtx_unlock(&sndstat_lock);
sx_unlock(&sndstat_lock);
return ENXIO;
}
@ -325,18 +320,18 @@ sndstat_unregisterfile(char *str)
{
struct sndstat_entry *ent;
mtx_lock(&sndstat_lock);
sx_xlock(&sndstat_lock);
SLIST_FOREACH(ent, &sndstat_devlist, link) {
if (ent->dev == NULL && ent->str == str) {
SLIST_REMOVE(&sndstat_devlist, ent, sndstat_entry, link);
sndstat_files--;
mtx_unlock(&sndstat_lock);
sx_unlock(&sndstat_lock);
free(ent, M_DEVBUF);
return 0;
}
}
mtx_unlock(&sndstat_lock);
sx_unlock(&sndstat_lock);
return ENXIO;
}
@ -399,7 +394,7 @@ sndstat_init(void)
{
if (sndstat_dev != NULL)
return EINVAL;
mtx_init(&sndstat_lock, "sndstat", "sndstat lock", MTX_DEF);
sx_init(&sndstat_lock, "sndstat lock");
sndstat_dev = make_dev(&sndstat_cdevsw, SND_DEV_STATUS,
UID_ROOT, GID_WHEEL, 0444, "sndstat");
return 0;
@ -411,20 +406,20 @@ sndstat_uninit(void)
if (sndstat_dev == NULL)
return EINVAL;
mtx_lock(&sndstat_lock);
sx_xlock(&sndstat_lock);
if (SNDSTAT_PID(sndstat_dev) != curthread->td_proc->p_pid) {
mtx_unlock(&sndstat_lock);
sx_unlock(&sndstat_lock);
return EBUSY;
}
SNDSTAT_FLUSH();
mtx_unlock(&sndstat_lock);
/* XXXPHO: use destroy_dev_sched() */
destroy_dev(sndstat_dev);
sndstat_dev = NULL;
mtx_destroy(&sndstat_lock);
SNDSTAT_FLUSH();
sx_unlock(&sndstat_lock);
sx_destroy(&sndstat_lock);
return 0;
}