On 08/27/2012 03:34 PM, Baodong Chen wrote: Sorry, I do not get this change. You should not touch tty_driver.kref at all.
And what is the patch good for? > Signed-off-by: Baodong Chen <[email protected]> > --- > drivers/staging/net/pc300_tty.c | 55 > ++++++++++++++++++++++----------------- > 1 files changed, 31 insertions(+), 24 deletions(-) > > diff --git a/drivers/staging/net/pc300_tty.c b/drivers/staging/net/pc300_tty.c > index 4709f42..91ada93 100644 > --- a/drivers/staging/net/pc300_tty.c > +++ b/drivers/staging/net/pc300_tty.c > @@ -46,6 +46,8 @@ > #include <linux/slab.h> > #include <linux/if.h> > #include <linux/skbuff.h> > +#include <linux/kref.h> > + > /* TTY includes */ > #include <linux/tty.h> > #include <linux/tty_flip.h> > @@ -134,12 +136,26 @@ static void cpc_tty_signal_on(pc300dev_t *pc300dev, > unsigned char); > static int pc300_tiocmset(struct tty_struct *, unsigned int, unsigned int); > static int pc300_tiocmget(struct tty_struct *); > > +static void cpc_tty_do_unreg_driver(struct kref *ref); > + > /* functions called by PC300 driver */ > void cpc_tty_init(pc300dev_t *dev); > void cpc_tty_unregister_service(pc300dev_t *pc300dev); > void cpc_tty_receive(pc300dev_t *pc300dev); > void cpc_tty_trigger_poll(pc300dev_t *pc300dev); > > +static void cpc_tty_do_unreg_driver(struct kref *ref) > +{ > + struct tty_driver *drv = container_of(ref, struct tty_driver, kref); > + int ret; > + > + cpc_tty_unreg_flag = 0; > + > + res = tty_unregister_driver(drv); > + if (res) > + CPC_TTY_DBG("unregister the tty driver error=%d\n", res); > +} > + > /* > * PC300 TTY clear "signal" > */ > @@ -239,6 +255,8 @@ void cpc_tty_init(pc300dev_t *pc300dev) > /* interface routines from the upper tty layer to the tty > driver */ > tty_set_operations(&serial_drv, &pc300_ops); > > + kref_init(&serial_drv.kref); > + > /* register the TTY driver */ > if (tty_register_driver(&serial_drv)) { > printk("%s-tty: Failed to register serial driver! ", > @@ -408,13 +426,9 @@ static void cpc_tty_close(struct tty_struct *tty, struct > file *flip) > > CPC_TTY_DBG("%s: TTY closed\n",cpc_tty->name); > > - if (!serial_drv.refcount && cpc_tty_unreg_flag) { > - cpc_tty_unreg_flag = 0; > - CPC_TTY_DBG("%s: unregister the tty driver\n", cpc_tty->name); > - if ((res=tty_unregister_driver(&serial_drv))) { > - CPC_TTY_DBG("%s: ERROR ->unregister the tty driver > error=%d\n", > - cpc_tty->name,res); > - } > + if (cpc_tty_unreg_flag) { > + CPC_TTY_DBG("%s: checking unregister the tty driver...\n", > cpc_tty->name); > + kref_put(&serial_drv.kref, cpc_tty_do_unreg_driver); > } > return; > } > @@ -644,13 +658,9 @@ static void cpc_tty_hangup(struct tty_struct *tty) > CPC_TTY_DBG("%s: TTY is not opened\n",cpc_tty->name); > return ; > } > - if (!serial_drv.refcount && cpc_tty_unreg_flag) { > - cpc_tty_unreg_flag = 0; > - CPC_TTY_DBG("%s: unregister the tty driver\n", cpc_tty->name); > - if ((res=tty_unregister_driver(&serial_drv))) { > - CPC_TTY_DBG("%s: ERROR ->unregister the tty driver > error=%d\n", > - cpc_tty->name,res); > - } > + if (cpc_tty_unreg_flag) { > + CPC_TTY_DBG("%s: checking unregister the tty driver...\n", > cpc_tty->name); > + kref_put(&serial_drv.kref, cpc_tty_do_unreg_driver); > } > cpc_tty_signal_off(cpc_tty->pc300dev, CTL_DTR); > } > @@ -1043,19 +1053,16 @@ void cpc_tty_unregister_service(pc300dev_t *pc300dev) > return; > } > > - if (--cpc_tty_cnt == 0) { > - if (serial_drv.refcount) { > - CPC_TTY_DBG("%s: unregister is not possible, > refcount=%d", > - cpc_tty->name, > serial_drv.refcount); > + if (--cpc_tty_cnt == 0) { > + CPC_TTY_DBG("%s: checking unregister the tty driver...\n", > + cpc_tty->name); > + res = kref_put(&serial_drv.kref, cpc_tty_do_unreg_driver); > + if (0 == res) { > + CPC_TTY_DBG("%s: unregister is not possible\n", > + cpc_tty->name); > cpc_tty_cnt++; > cpc_tty_unreg_flag = 1; > return; > - } else { > - CPC_TTY_DBG("%s: unregister the tty driver\n", > cpc_tty->name); > - if ((res=tty_unregister_driver(&serial_drv))) { > - CPC_TTY_DBG("%s: ERROR ->unregister the tty > driver error=%d\n", > - > cpc_tty->name,res); > - } > } > } > CPC_TTY_LOCK(pc300dev->chan->card,flags); > -- js suse labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
