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 <chenbdchenbd@xxxxxxxxx>
> ---
> 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
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