[PATCH net-next] net: pktgen: Use wait_event_freezable_timeout() for freezable kthread

[PATCH net-next] net: pktgen: Use wait_event_freezable_timeout() for freezable kthread

[Kevin Hao]

A freezable kernel thread can enter frozen state during freezing by
either calling try_to_freeze() or using wait_event_freezable() and its
variants. So for the following snippet of code in a kernel thread loop:
  wait_event_interruptible_timeout();
  try_to_freeze();

We can change it to a simple wait_event_freezable_timeout() and then
eliminate a function call.

Signed-off-by: Kevin Hao <haokexin@gmail.com>
---
 net/core/pktgen.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 57cea67b7562..2b59fc66fe26 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -3669,10 +3669,8 @@ static int pktgen_thread_worker(void *arg)
 		if (unlikely(!pkt_dev && t->control == 0)) {
 			if (t->net->pktgen_exiting)
 				break;
-			wait_event_interruptible_timeout(t->queue,
-							 t->control != 0,
-							 HZ/10);
-			try_to_freeze();
+			wait_event_freezable_timeout(t->queue,
+						     t->control != 0, HZ/10);
 			continue;
 		}
 
-- 
2.39.2

Re: [PATCH net-next] net: pktgen: Use wait_event_freezable_timeout() for freezable kthread

[Paolo Abeni]

On Sat, 2023-12-16 at 19:26 +0800, Kevin Hao wrote:
> A freezable kernel thread can enter frozen state during freezing by
> either calling try_to_freeze() or using wait_event_freezable() and its
> variants. So for the following snippet of code in a kernel thread loop:
>   wait_event_interruptible_timeout();
>   try_to_freeze();
> 
> We can change it to a simple wait_event_freezable_timeout() and then
> eliminate a function call.
> 
> Signed-off-by: Kevin Hao <haokexin@gmail.com>
> ---
>  net/core/pktgen.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/net/core/pktgen.c b/net/core/pktgen.c
> index 57cea67b7562..2b59fc66fe26 100644
> --- a/net/core/pktgen.c
> +++ b/net/core/pktgen.c
> @@ -3669,10 +3669,8 @@ static int pktgen_thread_worker(void *arg)
>  		if (unlikely(!pkt_dev && t->control == 0)) {
>  			if (t->net->pktgen_exiting)
>  				break;
> -			wait_event_interruptible_timeout(t->queue,
> -							 t->control != 0,
> -							 HZ/10);
> -			try_to_freeze();
> +			wait_event_freezable_timeout(t->queue,
> +						     t->control != 0, HZ/10);

The patch looks functionally correct to me, so I'm sorry to nit-pick. 

Since you touch the last line just for a 'cosmetic' change, please make
checkpatch happy, too:  please replace 'HZ/10' with 'HZ / 10'.

Thanks!

Paolo

Re: [PATCH net-next] net: pktgen: Use wait_event_freezable_timeout() for freezable kthread

[Kevin Hao]

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On Tue, Dec 19, 2023 at 01:37:23PM +0100, Paolo Abeni wrote:
> On Sat, 2023-12-16 at 19:26 +0800, Kevin Hao wrote:
> > A freezable kernel thread can enter frozen state during freezing by
> > either calling try_to_freeze() or using wait_event_freezable() and its
> > variants. So for the following snippet of code in a kernel thread loop:
> >   wait_event_interruptible_timeout();
> >   try_to_freeze();
> > 
> > We can change it to a simple wait_event_freezable_timeout() and then
> > eliminate a function call.
> > 
> > Signed-off-by: Kevin Hao <haokexin@gmail.com>
> > ---
> >  net/core/pktgen.c | 6 ++----
> >  1 file changed, 2 insertions(+), 4 deletions(-)
> > 
> > diff --git a/net/core/pktgen.c b/net/core/pktgen.c
> > index 57cea67b7562..2b59fc66fe26 100644
> > --- a/net/core/pktgen.c
> > +++ b/net/core/pktgen.c
> > @@ -3669,10 +3669,8 @@ static int pktgen_thread_worker(void *arg)
> >  		if (unlikely(!pkt_dev && t->control == 0)) {
> >  			if (t->net->pktgen_exiting)
> >  				break;
> > -			wait_event_interruptible_timeout(t->queue,
> > -							 t->control != 0,
> > -							 HZ/10);
> > -			try_to_freeze();
> > +			wait_event_freezable_timeout(t->queue,
> > +						     t->control != 0, HZ/10);
> 
> The patch looks functionally correct to me, so I'm sorry to nit-pick. 
> 
> Since you touch the last line just for a 'cosmetic' change, please make
> checkpatch happy, too:  please replace 'HZ/10' with 'HZ / 10'.

Yes, I saw the complaint from checkpatch before sending this patch, but I
thought I should keep it as it is. :-)
Anyway, v2 is coming.

Thanks,
Kevin
> 
> Thanks!
> 
> Paolo
> 

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