[PATCH] clk: Properly initialize reference count

[PATCH] clk: Properly initialize reference count

[Thierry Reding]

Commit a336ed7 (clk: Implement clk_unregister()) initializes the kref in
clk_set_parent(), which is obviously the wrong place. Further research
shows that the original patches initialized it correctly, so it probably
ended up in clk_set_parent() by mistake during manual application of the
patch.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
 drivers/clk/clk.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 6e3f485..b68a999 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1750,7 +1750,6 @@ int clk_set_parent(struct clk *clk, struct clk *parent)
 	else
 		__clk_recalc_rates(clk, POST_RATE_CHANGE);
 
-	kref_init(&clk->ref);
 out:
 	clk_prepare_unlock();
 
@@ -1906,6 +1905,7 @@ int __clk_init(struct device *dev, struct clk *clk)
 	if (clk->ops->init)
 		clk->ops->init(clk->hw);
 
+	kref_init(&clk->ref);
 out:
 	clk_prepare_unlock();
 
-- 
1.8.4

[PATCH] clk: Properly initialize reference count

[Stephen Warren]

On 10/31/2013 06:02 AM, Thierry Reding wrote:
> Commit a336ed7 (clk: Implement clk_unregister()) initializes the kref in
> clk_set_parent(), which is obviously the wrong place. Further research
> shows that the original patches initialized it correctly, so it probably
> ended up in clk_set_parent() by mistake during manual application of the
> patch.

Tested-by: Stephen Warren <swarren@nvidia.com>

BTW, it'd be nice to Cc fixes like this to linux-next at vger.kernel.org; I
/might/ have avoided doing a bisect if I'd seen this patch first!

I see the benefit of that "linux-next plus today's accumulated
bug-fixes" tree that I think you proposed:-)

[PATCH] clk: Properly initialize reference count

[Thierry Reding]

On Thu, Oct 31, 2013 at 01:09:11PM -0600, Stephen Warren wrote:
> On 10/31/2013 06:02 AM, Thierry Reding wrote:
> > Commit a336ed7 (clk: Implement clk_unregister()) initializes the kref in
> > clk_set_parent(), which is obviously the wrong place. Further research
> > shows that the original patches initialized it correctly, so it probably
> > ended up in clk_set_parent() by mistake during manual application of the
> > patch.
> 
> Tested-by: Stephen Warren <swarren@nvidia.com>
> 
> BTW, it'd be nice to Cc fixes like this to linux-next at vger.kernel.org;

Yes, perhaps that would've been a good idea.

> I /might/ have avoided doing a bisect if I'd seen this patch first!

I get that bisect is a really nice tool. But I don't understand why
people seem to rely on it to track down *everything* nowadays. In this
particular case there was a fairly obvious warning that pretty clearly
pointed at something wrong with the reference counting and some simple
code inspection revealed the issue at hand. No need to rebuild and boot
the kernel dozens of times to find this out.

But perhaps other people have much faster machines and bisection is
actually faster...

> I see the benefit of that "linux-next plus today's accumulated
> bug-fixes" tree that I think you proposed:-)

Yeah, this is precisely the situation where this would be good to have.
Both of these issues together took about 45-60 minutes to track down and
fix. I suppose it took Olof and you a similar amount of time. Yet if the
fixes were already collected in some standard location it would free you
up to do something more productive instead of wasting your time on
duplicate work.

I'll ask Stephen (Rothwell) if he'd be willing to set up shared access
to linux-next so that I can push collected fixes. Alternatively I could
do that in a separate repository.

Thierry
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[PATCH] clk: Properly initialize reference count

[Fabio Estevam]

On Thu, Oct 31, 2013 at 10:02 AM, Thierry Reding
<thierry.reding@gmail.com> wrote:
> Commit a336ed7 (clk: Implement clk_unregister()) initializes the kref in
> clk_set_parent(), which is obviously the wrong place. Further research
> shows that the original patches initialized it correctly, so it probably
> ended up in clk_set_parent() by mistake during manual application of the
> patch.
>
> Signed-off-by: Thierry Reding <treding@nvidia.com>

Tested-by: Fabio Estevam <fabio.estevam@freescale.com>

[PATCH] clk: Properly initialize reference count

[Jonas Jensen]

On 31 October 2013 13:02, Thierry Reding <thierry.reding@gmail.com> wrote:
> Commit a336ed7 (clk: Implement clk_unregister()) initializes the kref in
> clk_set_parent(), which is obviously the wrong place. Further research
> shows that the original patches initialized it correctly, so it probably
> ended up in clk_set_parent() by mistake during manual application of the
> patch.

Tested-by: Jonas Jensen <jonas.jensen@gmail.com>

Thanks!