2019-09-26 07:47:30

by Xiaoming Ni

Subject: [PATCH] tty:n_gsm.c: destroy port by tty_port_destroy()

According to the comment of tty_port_destroy():
When a port was initialized using tty_port_init, one has to destroy
the port by tty_port_destroy();

tty_port_init() is called in gsm_dlci_alloc()
so tty_port_destroy() needs to be called in gsm_dlci_free()

Signed-off-by: Xiaoming Ni <[email protected]>
---
drivers/tty/n_gsm.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 36a3eb4..3f5bcc9 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -1681,6 +1681,7 @@ static void gsm_dlci_free(struct tty_port *port)

del_timer_sync(&dlci->t1);
dlci->gsm->dlci[dlci->addr] = NULL;
+ tty_port_destroy(&dlci->port);
kfifo_free(dlci->fifo);
while ((dlci->skb = skb_dequeue(&dlci->skb_list)))
dev_kfree_skb(dlci->skb);
--
1.8.5.6

2019-10-31 10:12:22

by Jiri Slaby

Subject: Re: [PATCH] tty:n_gsm.c: destroy port by tty_port_destroy()

On 24. 09. 19, 11:25, Xiaoming Ni wrote:
> According to the comment of tty_port_destroy():
> When a port was initialized using tty_port_init, one has to destroy
> the port by tty_port_destroy();

It continues with a part saying:
Either indirectly by using tty_port refcounting
(tty_port_put) or directly if refcounting is not used.

> tty_port_init() is called in gsm_dlci_alloc()
> so tty_port_destroy() needs to be called in gsm_dlci_free()
>
> Signed-off-by: Xiaoming Ni <[email protected]>
> ---
> drivers/tty/n_gsm.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
> index 36a3eb4..3f5bcc9 100644
> --- a/drivers/tty/n_gsm.c
> +++ b/drivers/tty/n_gsm.c
> @@ -1681,6 +1681,7 @@ static void gsm_dlci_free(struct tty_port *port)
>
> del_timer_sync(&dlci->t1);
> dlci->gsm->dlci[dlci->addr] = NULL;
> + tty_port_destroy(&dlci->port);

This is wrong. gsm_dlci_free is tty_port_operations->destruct, i.e.
n_gsm uses tty_port refcounting and tty_port_destroy was called on this
port in tty_port_destructor already.

Greg, please revert.

thanks,
--
js
suse labs

2019-10-31 12:40:49

by Xiaoming Ni

Subject: Re: [PATCH] tty:n_gsm.c: destroy port by tty_port_destroy()

On 2019/10/31 18:11, Jiri Slaby wrote:
> On 24. 09. 19, 11:25, Xiaoming Ni wrote:
>> According to the comment of tty_port_destroy():
>> When a port was initialized using tty_port_init, one has to destroy
>> the port by tty_port_destroy();
>
> It continues with a part saying:
> Either indirectly by using tty_port refcounting
> (tty_port_put) or directly if refcounting is not used.
>
>> tty_port_init() is called in gsm_dlci_alloc()
>> so tty_port_destroy() needs to be called in gsm_dlci_free()
>>
>> Signed-off-by: Xiaoming Ni <[email protected]>
>> ---
>> drivers/tty/n_gsm.c | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
>> index 36a3eb4..3f5bcc9 100644
>> --- a/drivers/tty/n_gsm.c
>> +++ b/drivers/tty/n_gsm.c
>> @@ -1681,6 +1681,7 @@ static void gsm_dlci_free(struct tty_port *port)
>>
>> del_timer_sync(&dlci->t1);
>> dlci->gsm->dlci[dlci->addr] = NULL;
>> + tty_port_destroy(&dlci->port);
>
> This is wrong. gsm_dlci_free is tty_port_operations->destruct, i.e.
> n_gsm uses tty_port refcounting and tty_port_destroy was called on this
> port in tty_port_destructor already.
>
> Greg, please revert.
>
> thanks,
>

Function call flow
tty_port_put
===> tty_port_destructor
??????? ===> tty_port_destroy
?????????? Port->ops->destruct(port);
?????????????? ===> .destruct = gsm_dlci_free

Thank you for your correction, I am wrong.

thanks

2019-11-04 16:51:05

by Greg Kroah-Hartman

Subject: Re: [PATCH] tty:n_gsm.c: destroy port by tty_port_destroy()

On Thu, Oct 31, 2019 at 11:11:24AM +0100, Jiri Slaby wrote:
> On 24. 09. 19, 11:25, Xiaoming Ni wrote:
> > According to the comment of tty_port_destroy():
> > When a port was initialized using tty_port_init, one has to destroy
> > the port by tty_port_destroy();
>
> It continues with a part saying:
> Either indirectly by using tty_port refcounting
> (tty_port_put) or directly if refcounting is not used.
>
> > tty_port_init() is called in gsm_dlci_alloc()
> > so tty_port_destroy() needs to be called in gsm_dlci_free()
> >
> > Signed-off-by: Xiaoming Ni <[email protected]>
> > ---
> > drivers/tty/n_gsm.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
> > index 36a3eb4..3f5bcc9 100644
> > --- a/drivers/tty/n_gsm.c
> > +++ b/drivers/tty/n_gsm.c
> > @@ -1681,6 +1681,7 @@ static void gsm_dlci_free(struct tty_port *port)
> >
> > del_timer_sync(&dlci->t1);
> > dlci->gsm->dlci[dlci->addr] = NULL;
> > + tty_port_destroy(&dlci->port);
>
> This is wrong. gsm_dlci_free is tty_port_operations->destruct, i.e.
> n_gsm uses tty_port refcounting and tty_port_destroy was called on this
> port in tty_port_destructor already.
>
> Greg, please revert.

Now reverted.

sorry about that.

greg k-h