LinuxLists.cc - [Bluez-devel] Re: [PATCH 18/39] net/core: use wait_event

2005-01-21 00:32:14

Subject: [Bluez-devel] Re: [PATCH 18/39] net/core: use wait_event_timeout()

2005-01-26 05:56:39

Subject: Re: [UPDATE PATCH 18/39] net/core: use wait_event_timeout()

On Sun, 23 Jan 2005 10:21:08 +0100
Marcel Holtmann <[email protected]> wrote:

> we are using the wait queue from struct sock and sk_sleep is already a
> pointer. Converting from and to a pointer and later to the struct again
> to only match an API looks wrong to me and thus this API is wrong, but
> this is only my thought.
>
> Dave, any comments from you about this?

Not really. I think the API is ok, it's a tradeoff between one set
of call types putting in a deref compared to the other. And as the
patch author stated, the bluetooth side is definitely in the
minority.

To be honest, I think the decision is arbitrary.

2005-01-23 09:21:08

by Marcel Holtmann

[permalink] [raw]

Subject: [Bluez-devel] Re: [UPDATE PATCH 18/39] net/core: use wait_event_timeout()

Hi Nish,

> > > Description: Use wait_event_timeout() instead of custom wait-queue code.
> > > The current code uses TASK_INTERRUPTIBLE but only cares about timing out and the
> > > wq event taking place (does not actively do anything in response to signals), so
> > > wait_event_timeout() should be ok.
> > >
> > > Signed-off-by: Nishanth Aravamudan <[email protected]>
> > >
> > >
> > > --- 2.6.11-rc1-kj-v/net/bluetooth/hidp/core.c 2005-01-15 16:55:44.000000000 -0800
> > > +++ 2.6.11-rc1-kj/net/bluetooth/hidp/core.c 2005-01-21 11:07:11.000000000 -0800
> > > @@ -36,6 +36,7 @@
> > > #include <linux/ioctl.h>
> > > #include <linux/file.h>
> > > #include <linux/init.h>
> > > +#include <linux/wait.h>
> > > #include <net/sock.h>
> > >
> > > #include <linux/input.h>
> > > @@ -325,7 +326,6 @@ static int hidp_session(void *arg)
> > > struct sk_buff *skb;
> > > int vendor = 0x0000, product = 0x0000;
> > > wait_queue_t ctrl_wait, intr_wait;
> > > - unsigned long timeo = HZ;
> > >
> > > BT_DBG("session %p", session);
> > >
> > > @@ -370,28 +370,14 @@ static int hidp_session(void *arg)
> > >
> > > hidp_del_timer(session);
> > >
> > > - if (intr_sk->sk_state != BT_CONNECTED) {
> > > - init_waitqueue_entry(&ctrl_wait, current);
> > > - add_wait_queue(ctrl_sk->sk_sleep, &ctrl_wait);
> > > - while (timeo && ctrl_sk->sk_state != BT_CLOSED) {
> > > - set_current_state(TASK_INTERRUPTIBLE);
> > > - timeo = schedule_timeout(timeo);
> > > - }
> > > - set_current_state(TASK_RUNNING);
> > > - remove_wait_queue(ctrl_sk->sk_sleep, &ctrl_wait);
> > > - timeo = HZ;
> > > - }
> > > + if (intr_sk->sk_state != BT_CONNECTED)
> > > + wait_event_timeout(*(ctrl_sk->sk_sleep),
> > > + (ctrl_sk->sk_state == BT_CLOSED), HZ);
> >
> > and this does not make it look better. For me this is too much pointer
> > stuff here. I think the interface of wait_event_timeout() is wrong. It
> > should take a pointer to wait_queue_head_t.
>
> Maybe; I'm not the designer of the interface, though, so I was just
> trying to use what exists. To be honest, this particular driver is the
> *only* one of a good number I've tried to convert that has this issue.
> Everywhere else, {add,remove}_wait_queue() is called like so:
>
> {add,remove}_wait_queue(&wq, &wait);
>
> just as it is called via prepare_to_wait() in wait_event(). core.c is
> the first driver I've come across that called the functions via:
>
> {add,remove}_wait_queue(wq, &wait);
>
> wait_event() is just a large macro which expands to the first form,
> given wq as a parameter, so I think it should be ok, as that form is
> the far more common one in the kernel currently.

we are using the wait queue from struct sock and sk_sleep is already a
pointer. Converting from and to a pointer and later to the struct again
to only match an API looks wrong to me and thus this API is wrong, but
this is only my thought.

Dave, any comments from you about this?

Regards

Marcel

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2005-01-22 18:44:20

by Nish Aravamudan

[permalink] [raw]

Subject: Re: [KJ] Re: [UPDATE PATCH 18/39] net/core: use wait_event_timeout()

On Sat, 22 Jan 2005 18:57:28 +0100, Marcel Holtmann <[email protected]> wrote:
> Hi Nishanth,
>
> > Description: Use wait_event_timeout() instead of custom wait-queue code.
> > The current code uses TASK_INTERRUPTIBLE but only cares about timing out and the
> > wq event taking place (does not actively do anything in response to signals), so
> > wait_event_timeout() should be ok.
> >
> > Signed-off-by: Nishanth Aravamudan <[email protected]>
> >
> >
> > --- 2.6.11-rc1-kj-v/net/bluetooth/hidp/core.c 2005-01-15 16:55:44.000000000 -0800
> > +++ 2.6.11-rc1-kj/net/bluetooth/hidp/core.c 2005-01-21 11:07:11.000000000 -0800
> > @@ -36,6 +36,7 @@
> > #include <linux/ioctl.h>
> > #include <linux/file.h>
> > #include <linux/init.h>
> > +#include <linux/wait.h>
> > #include <net/sock.h>
> >
> > #include <linux/input.h>
> > @@ -325,7 +326,6 @@ static int hidp_session(void *arg)
> > struct sk_buff *skb;
> > int vendor = 0x0000, product = 0x0000;
> > wait_queue_t ctrl_wait, intr_wait;
> > - unsigned long timeo = HZ;
> >
> > BT_DBG("session %p", session);
> >
> > @@ -370,28 +370,14 @@ static int hidp_session(void *arg)
> >
> > hidp_del_timer(session);
> >
> > - if (intr_sk->sk_state != BT_CONNECTED) {
> > - init_waitqueue_entry(&ctrl_wait, current);
> > - add_wait_queue(ctrl_sk->sk_sleep, &ctrl_wait);
> > - while (timeo && ctrl_sk->sk_state != BT_CLOSED) {
> > - set_current_state(TASK_INTERRUPTIBLE);
> > - timeo = schedule_timeout(timeo);
> > - }
> > - set_current_state(TASK_RUNNING);
> > - remove_wait_queue(ctrl_sk->sk_sleep, &ctrl_wait);
> > - timeo = HZ;
> > - }
> > + if (intr_sk->sk_state != BT_CONNECTED)
> > + wait_event_timeout(*(ctrl_sk->sk_sleep),
> > + (ctrl_sk->sk_state == BT_CLOSED), HZ);
>
> and this does not make it look better. For me this is too much pointer
> stuff here. I think the interface of wait_event_timeout() is wrong. It
> should take a pointer to wait_queue_head_t.

Maybe; I'm not the designer of the interface, though, so I was just
trying to use what exists. To be honest, this particular driver is the
*only* one of a good number I've tried to convert that has this issue.
Everywhere else, {add,remove}_wait_queue() is called like so:

{add,remove}_wait_queue(&wq, &wait);

just as it is called via prepare_to_wait() in wait_event(). core.c is
the first driver I've come across that called the functions via:

{add,remove}_wait_queue(wq, &wait);

wait_event() is just a large macro which expands to the first form,
given wq as a parameter, so I think it should be ok, as that form is
the far more common one in the kernel currently.

What do you think? I am open to other ideas/suggestions, but I'm not
certain changing an existing / working interface (which other drivers
are being converted to) is the best idea.

Thanks,
Nish

2005-01-22 17:57:28

by Marcel Holtmann

[permalink] [raw]

Subject: [Bluez-devel] Re: [UPDATE PATCH 18/39] net/core: use wait_event_timeout()

Hi Nishanth,

> Description: Use wait_event_timeout() instead of custom wait-queue code.
> The current code uses TASK_INTERRUPTIBLE but only cares about timing out and the
> wq event taking place (does not actively do anything in response to signals), so
> wait_event_timeout() should be ok.
>
> Signed-off-by: Nishanth Aravamudan <[email protected]>
>
>
> --- 2.6.11-rc1-kj-v/net/bluetooth/hidp/core.c 2005-01-15 16:55:44.000000000 -0800
> +++ 2.6.11-rc1-kj/net/bluetooth/hidp/core.c 2005-01-21 11:07:11.000000000 -0800
> @@ -36,6 +36,7 @@
> #include <linux/ioctl.h>
> #include <linux/file.h>
> #include <linux/init.h>
> +#include <linux/wait.h>
> #include <net/sock.h>
>
> #include <linux/input.h>
> @@ -325,7 +326,6 @@ static int hidp_session(void *arg)
> struct sk_buff *skb;
> int vendor = 0x0000, product = 0x0000;
> wait_queue_t ctrl_wait, intr_wait;
> - unsigned long timeo = HZ;
>
> BT_DBG("session %p", session);
>
> @@ -370,28 +370,14 @@ static int hidp_session(void *arg)
>
> hidp_del_timer(session);
>
> - if (intr_sk->sk_state != BT_CONNECTED) {
> - init_waitqueue_entry(&ctrl_wait, current);
> - add_wait_queue(ctrl_sk->sk_sleep, &ctrl_wait);
> - while (timeo && ctrl_sk->sk_state != BT_CLOSED) {
> - set_current_state(TASK_INTERRUPTIBLE);
> - timeo = schedule_timeout(timeo);
> - }
> - set_current_state(TASK_RUNNING);
> - remove_wait_queue(ctrl_sk->sk_sleep, &ctrl_wait);
> - timeo = HZ;
> - }
> + if (intr_sk->sk_state != BT_CONNECTED)
> + wait_event_timeout(*(ctrl_sk->sk_sleep),
> + (ctrl_sk->sk_state == BT_CLOSED), HZ);

and this does not make it look better. For me this is too much pointer
stuff here. I think the interface of wait_event_timeout() is wrong. It
should take a pointer to wait_queue_head_t.

Regards

Marcel

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2005-01-21 19:09:09

by Nishanth Aravamudan

[permalink] [raw]

Subject: [UPDATE PATCH 18/39] net/core: use wait_event_timeout()

On Fri, Jan 21, 2005 at 01:32:14AM +0100, Marcel Holtmann wrote:
> Hi Nishanth,
>
> > Description: Use wait_event_timeout() instead of custom wait-queue code.
> > The current code uses TASK_INTERRUPTIBLE but only cares about timing out and the
> > wq event taking place (does not actively do anything in response to signals), so
> > wait_event_timeout() should be ok.
>
> this one results in:
>
> CC [M] net/bluetooth/hidp/core.o
> net/bluetooth/hidp/core.c: In function `hidp_session':
> net/bluetooth/hidp/core.c:547: warning: passing arg 1 of `prepare_to_wait' from incompatible pointer type
> net/bluetooth/hidp/core.c:547: warning: passing arg 1 of `finish_wait' from incompatible pointer type
> net/bluetooth/hidp/core.c:551: warning: passing arg 1 of `prepare_to_wait' from incompatible pointer type
> net/bluetooth/hidp/core.c:551: warning: passing arg 1 of `finish_wait' from incompatible pointer type

Sorry for that, Marcel. The calling case in that function is slightly different
than usual...fixed below.

Thanks,
Nish

Description: Use wait_event_timeout() instead of custom wait-queue code.
The current code uses TASK_INTERRUPTIBLE but only cares about timing out and the
wq event taking place (does not actively do anything in response to signals), so
wait_event_timeout() should be ok.

Signed-off-by: Nishanth Aravamudan <[email protected]>

--- 2.6.11-rc1-kj-v/net/bluetooth/hidp/core.c 2005-01-15 16:55:44.000000000 -0800
+++ 2.6.11-rc1-kj/net/bluetooth/hidp/core.c 2005-01-21 11:07:11.000000000 -0800
@@ -36,6 +36,7 @@
#include <linux/ioctl.h>
#include <linux/file.h>
#include <linux/init.h>
+#include <linux/wait.h>
#include <net/sock.h>

#include <linux/input.h>
@@ -325,7 +326,6 @@ static int hidp_session(void *arg)
struct sk_buff *skb;
int vendor = 0x0000, product = 0x0000;
wait_queue_t ctrl_wait, intr_wait;
- unsigned long timeo = HZ;

BT_DBG("session %p", session);

@@ -370,28 +370,14 @@ static int hidp_session(void *arg)

hidp_del_timer(session);

- if (intr_sk->sk_state != BT_CONNECTED) {
- init_waitqueue_entry(&ctrl_wait, current);
- add_wait_queue(ctrl_sk->sk_sleep, &ctrl_wait);
- while (timeo && ctrl_sk->sk_state != BT_CLOSED) {
- set_current_state(TASK_INTERRUPTIBLE);
- timeo = schedule_timeout(timeo);
- }
- set_current_state(TASK_RUNNING);
- remove_wait_queue(ctrl_sk->sk_sleep, &ctrl_wait);
- timeo = HZ;
- }
+ if (intr_sk->sk_state != BT_CONNECTED)
+ wait_event_timeout(*(ctrl_sk->sk_sleep),
+ (ctrl_sk->sk_state == BT_CLOSED), HZ);

fput(session->ctrl_sock->file);

- init_waitqueue_entry(&intr_wait, current);
- add_wait_queue(intr_sk->sk_sleep, &intr_wait);
- while (timeo && intr_sk->sk_state != BT_CLOSED) {
- set_current_state(TASK_INTERRUPTIBLE);
- timeo = schedule_timeout(timeo);
- }
- set_current_state(TASK_RUNNING);
- remove_wait_queue(intr_sk->sk_sleep, &intr_wait);
+ wait_event_timeout(*(ctrl_sk->sk_sleep),
+ (intr_sk->sk_state == BT_CLOSED), HZ);

fput(session->intr_sock->file);