Re: + softirq-fix-tasklet_kill-and-its-users.patch added to -mm tree

[Santosh Shilimkar]

This is a multi-part message in MIME format.
On 9/21/2016 1:09 AM, Sergey Senozhatsky wrote:
> didn't look into the issue, but this thing
Thanks for reporting Sergey.

> > > tasklet_init() == Init and Enable scheduling
> [..]
> > > @@ -559,7 +559,7 @@ void tasklet_init(struct tasklet_struct
> > >  {
> > >  	t->next = NULL;
> > >  	t->state = 0;
> > > -	atomic_set(&t->count, 0);
> > > +	atomic_set(&t->count, 1);

   			^^^^^^^^
> > >  	t->func = func;
> > >  	t->data = data;
> > >  }
>
> seems to be in conflict with
Static helpers also needs to follow the API.

>  #define DECLARE_TASKLET(name, func, data) \
>  struct tasklet_struct name = { NULL, 0, ATOMIC_INIT(0), func, data }
> 						^^^^^^^
>
>  #define DECLARE_TASKLET_DISABLED(name, func, data) \
>  struct tasklet_struct name = { NULL, 0, ATOMIC_INIT(1), func, data }
> 						^^^^^^^

> as well as with the tasklet_{disable, enable} helpers
Those are fine since they work like a pair and the use count
is always balanced.

Am assuming one of the driver in your test is using the DECLARE_TASKLET
to init the tasklet and killed by tasklet_kill() which leaves that
tasklet to be still scheduled by tasklet action.

Can you please try below patch and see if you still see the issue ?
Attaching the same, just in case mailer eat the tabs.

Regards,
Santosh

From e3e676e501a59b2a7de6e9f99ec3917c157e9caf Mon Sep 17 00:00:00 2001
From: Santosh Shilimkar <ssantosh@xxxxxxxxxx>
Date: Wed, 21 Sep 2016 09:58:51 -0700
Subject: [PATCH] softirq: fix DECLARE_TASKLET[_DISABLE] macros init state

In linux-next, commit 1f5e9c3bc47f ("softirq: fix tasklet_kill() and its 
users")
changed the init state of the tasklet but missed to update the macros.

Fix them too.

Reported-by: Sergey Senozhatsky <sergey.senozhatsky.work@xxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Santosh Shilimkar <ssantosh@xxxxxxxxxx>
---
 include/linux/interrupt.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 72f0721..cabf575 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -521,10 +521,10 @@ struct tasklet_struct
 };

 #define DECLARE_TASKLET(name, func, data) \
-struct tasklet_struct name = { NULL, 0, ATOMIC_INIT(0), func, data }
+struct tasklet_struct name = { NULL, 0, ATOMIC_INIT(1), func, data }

 #define DECLARE_TASKLET_DISABLED(name, func, data) \
-struct tasklet_struct name = { NULL, 0, ATOMIC_INIT(1), func, data }
+struct tasklet_struct name = { NULL, 0, ATOMIC_INIT(2), func, data }


 enum
--
1.9.1