[PATCH 37/77] i2c: convert to idr_alloc()

[PATCH 37/77] i2c: convert to idr_alloc()

[Tejun Heo]

Convert to the much saner new idr interface.

Only compile tested.

Signed-off-by: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>
Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
---
 drivers/i2c/i2c-core.c | 45 ++++++++++-----------------------------------
 1 file changed, 10 insertions(+), 35 deletions(-)

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 66a30f7..795c916 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -935,25 +935,16 @@ out_list:
  */
 int i2c_add_adapter(struct i2c_adapter *adapter)
 {
-	int	id, res = 0;
-
-retry:
-	if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0)
-		return -ENOMEM;
+	int res;
 
 	mutex_lock(&core_lock);
-	/* "above" here means "above or equal to", sigh */
-	res = idr_get_new_above(&i2c_adapter_idr, adapter,
-				__i2c_first_dynamic_bus_num, &id);
+	res = idr_alloc(&i2c_adapter_idr, adapter,
+			__i2c_first_dynamic_bus_num, 0, GFP_KERNEL);
 	mutex_unlock(&core_lock);
-
-	if (res < 0) {
-		if (res == -EAGAIN)
-			goto retry;
+	if (res < 0)
 		return res;
-	}
 
-	adapter->nr = id;
+	adapter->nr = res;
 	return i2c_register_adapter(adapter);
 }
 EXPORT_SYMBOL(i2c_add_adapter);
@@ -984,33 +975,17 @@ EXPORT_SYMBOL(i2c_add_adapter);
 int i2c_add_numbered_adapter(struct i2c_adapter *adap)
 {
 	int	id;
-	int	status;
 
 	if (adap->nr == -1) /* -1 means dynamically assign bus id */
 		return i2c_add_adapter(adap);
-	if (adap->nr & ~MAX_IDR_MASK)
-		return -EINVAL;
-
-retry:
-	if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0)
-		return -ENOMEM;
 
 	mutex_lock(&core_lock);
-	/* "above" here means "above or equal to", sigh;
-	 * we need the "equal to" result to force the result
-	 */
-	status = idr_get_new_above(&i2c_adapter_idr, adap, adap->nr, &id);
-	if (status == 0 && id != adap->nr) {
-		status = -EBUSY;
-		idr_remove(&i2c_adapter_idr, id);
-	}
+	id = idr_alloc(&i2c_adapter_idr, adap, adap->nr, adap->nr + 1,
+		       GFP_KERNEL);
 	mutex_unlock(&core_lock);
-	if (status == -EAGAIN)
-		goto retry;
-
-	if (status == 0)
-		status = i2c_register_adapter(adap);
-	return status;
+	if (id < 0)
+		return id == -ENOSPC ? -EBUSY : id;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
 
-- 
1.8.1

Re: [PATCH 37/77] i2c: convert to idr_alloc()

[Mark Brown]

On Wed, Feb 06, 2013 at 11:40:09AM -0800, Tejun Heo wrote:
> Convert to the much saner new idr interface.
> 
> Only compile tested.

This broke I2C for me in -next today, I saw a spinlock bad magic error
calling pm_runtime_enable().  

Re: [PATCH 37/77] i2c: convert to idr_alloc()

[Tejun Heo]

Hello,

On Thu, Feb 07, 2013 at 03:28:31PM +0000, Mark Brown wrote:
> On Wed, Feb 06, 2013 at 11:40:09AM -0800, Tejun Heo wrote:
> > Convert to the much saner new idr interface.
> > 
> > Only compile tested.
> 
> This broke I2C for me in -next today, I saw a spinlock bad magic error
> calling pm_runtime_enable().  

Hmmm... weird, can't see where the difference in behavior would come
from.  The only material difference would be if id < 0 && id != -1 in
i2c_add_numbered_adapter(), which now would trigger WARN_ON_ONCE()
inside idr_alloc() instead of silently returning -EINVAL.

Can you please elaborate the failure?  I can't see how the idr
conversion would lead to spinlock bad magic error.  Does reverting
this patch make the problem go away?

Thanks.

--
tejun

Re: [PATCH 37/77] i2c: convert to idr_alloc()

[Mark Brown]

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On Thu, Feb 07, 2013 at 08:32:47AM -0800, Tejun Heo wrote:
> On Thu, Feb 07, 2013 at 03:28:31PM +0000, Mark Brown wrote:
> > On Wed, Feb 06, 2013 at 11:40:09AM -0800, Tejun Heo wrote:
> > > Convert to the much saner new idr interface.

> > > Only compile tested.

> > This broke I2C for me in -next today, I saw a spinlock bad magic error
> > calling pm_runtime_enable().  

> Hmmm... weird, can't see where the difference in behavior would come
> from.  The only material difference would be if id < 0 && id != -1 in
> i2c_add_numbered_adapter(), which now would trigger WARN_ON_ONCE()
> inside idr_alloc() instead of silently returning -EINVAL.

> Can you please elaborate the failure?  I can't see how the idr
> conversion would lead to spinlock bad magic error.  Does reverting
> this patch make the problem go away?

Yes, reverting the patch made the issue vanish.  I've no more
diagnostics I'm afraid, just a 10s timeout then bad magic - it looks
like memory corruption.  I'll try to find time to dig in more but not
sure when that'll happen.

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[PATCH v2] i2c: convert to idr_alloc()

[Tejun Heo]

Convert to the much saner new idr interface.

Only compile tested.

v2: The original conversion accidentally dropped a call to
    i2c_register_adapter() in i2c_add_numbered_adapter() leaving @adap
    uninitialized and unregistered.  Reported by Mark Brown.  Fix it.

Signed-off-by: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Reported-by: Mark Brown <broonie-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org>
Cc: Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>
Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
---
Heh, this is embarrassing.  I got too focused on the id allocation
itself and missed moving i2c_register_adapter() call.

I think this should fix the problem you're seeing.  Can you please
test this?

Thank you.

 drivers/i2c/i2c-core.c |   43 ++++++++++---------------------------------
 1 file changed, 10 insertions(+), 33 deletions(-)

--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -935,25 +935,16 @@ out_list:
  */
 int i2c_add_adapter(struct i2c_adapter *adapter)
 {
-	int	id, res = 0;
-
-retry:
-	if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0)
-		return -ENOMEM;
+	int res;
 
 	mutex_lock(&core_lock);
-	/* "above" here means "above or equal to", sigh */
-	res = idr_get_new_above(&i2c_adapter_idr, adapter,
-				__i2c_first_dynamic_bus_num, &id);
+	res = idr_alloc(&i2c_adapter_idr, adapter,
+			__i2c_first_dynamic_bus_num, 0, GFP_KERNEL);
 	mutex_unlock(&core_lock);
-
-	if (res < 0) {
-		if (res == -EAGAIN)
-			goto retry;
+	if (res < 0)
 		return res;
-	}
 
-	adapter->nr = id;
+	adapter->nr = res;
 	return i2c_register_adapter(adapter);
 }
 EXPORT_SYMBOL(i2c_add_adapter);
@@ -984,33 +975,19 @@ EXPORT_SYMBOL(i2c_add_adapter);
 int i2c_add_numbered_adapter(struct i2c_adapter *adap)
 {
 	int	id;
-	int	status;
 
 	if (adap->nr == -1) /* -1 means dynamically assign bus id */
 		return i2c_add_adapter(adap);
 	if (adap->nr & ~MAX_IDR_MASK)
 		return -EINVAL;
 
-retry:
-	if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0)
-		return -ENOMEM;
-
 	mutex_lock(&core_lock);
-	/* "above" here means "above or equal to", sigh;
-	 * we need the "equal to" result to force the result
-	 */
-	status = idr_get_new_above(&i2c_adapter_idr, adap, adap->nr, &id);
-	if (status == 0 && id != adap->nr) {
-		status = -EBUSY;
-		idr_remove(&i2c_adapter_idr, id);
-	}
+	id = idr_alloc(&i2c_adapter_idr, adap, adap->nr, adap->nr + 1,
+		       GFP_KERNEL);
 	mutex_unlock(&core_lock);
-	if (status == -EAGAIN)
-		goto retry;
-
-	if (status == 0)
-		status = i2c_register_adapter(adap);
-	return status;
+	if (id < 0)
+		return id == -ENOSPC ? -EBUSY : id;
+	return i2c_register_adapter(adap);
 }
 EXPORT_SYMBOL_GPL(i2c_add_numbered_adapter);
 

Re: [PATCH v2] i2c: convert to idr_alloc()

[Mark Brown]

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On Thu, Feb 07, 2013 at 08:55:47AM -0800, Tejun Heo wrote:

> Heh, this is embarrassing.  I got too focused on the id allocation
> itself and missed moving i2c_register_adapter() call.

> I think this should fix the problem you're seeing.  Can you please
> test this?

Oops :) I'll test this tomorrow, out of time for today.

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Re: [PATCH v2] i2c: convert to idr_alloc()

[Mark Brown]

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On Thu, Feb 07, 2013 at 08:55:47AM -0800, Tejun Heo wrote:
> Convert to the much saner new idr interface.
> 
> Only compile tested.

Tested-by: Mark Brown <broonie-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org>

Thanks!

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Re: [PATCH v2] i2c: convert to idr_alloc()

[Wolfram Sang]

Hi,

thanks for doing this cleanup series. Looks very worthwhile!

> --- a/drivers/i2c/i2c-core.c
> +++ b/drivers/i2c/i2c-core.c
> @@ -935,25 +935,16 @@ out_list:
>   */
>  int i2c_add_adapter(struct i2c_adapter *adapter)
>  {
> -	int	id, res = 0;
> -
> -retry:
> -	if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0)
> -		return -ENOMEM;
> +	int res;

I'd vote for using 'id' as the variable name here. Feels more logical to
me and you are using 'id' in the other block, too.

> @@ -984,33 +975,19 @@ EXPORT_SYMBOL(i2c_add_adapter);
>  int i2c_add_numbered_adapter(struct i2c_adapter *adap)
>  {
>  	int	id;
> -	int	status;
>  
>  	if (adap->nr == -1) /* -1 means dynamically assign bus id */
>  		return i2c_add_adapter(adap);
>  	if (adap->nr & ~MAX_IDR_MASK)
>  		return -EINVAL;
>  
> -retry:
> -	if (idr_pre_get(&i2c_adapter_idr, GFP_KERNEL) == 0)
> -		return -ENOMEM;
> -
>  	mutex_lock(&core_lock);
> -	/* "above" here means "above or equal to", sigh;
> -	 * we need the "equal to" result to force the result
> -	 */
> -	status = idr_get_new_above(&i2c_adapter_idr, adap, adap->nr, &id);
> -	if (status == 0 && id != adap->nr) {
> -		status = -EBUSY;
> -		idr_remove(&i2c_adapter_idr, id);
> -	}
> +	id = idr_alloc(&i2c_adapter_idr, adap, adap->nr, adap->nr + 1,
> +		       GFP_KERNEL);
>  	mutex_unlock(&core_lock);
> -	if (status == -EAGAIN)
> -		goto retry;
> -
> -	if (status == 0)
> -		status = i2c_register_adapter(adap);
> -	return status;
> +	if (id < 0)
> +		return id == -ENOSPC ? -EBUSY : id;
> +	return i2c_register_adapter(adap);

Add an empty line before the return statement?

Thanks,

   Wolfram

[PATCH -mm] i2c: style cleanups after idr_alloc() conversion

[Tejun Heo]

Style cleanups suggested by Wolfram.

* s/res/id/ in i2c_add_numbered_adapter() so that it matches
  i2c_add_adapter().

* Add a blank line before return in i2c_add_numbered_adapter().

This patch is purely cosmetic.

Signed-off-by: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
---
 drivers/i2c/i2c-core.c |   13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -935,16 +935,17 @@ out_list:
  */
 int i2c_add_adapter(struct i2c_adapter *adapter)
 {
-	int res;
+	int id;
 
 	mutex_lock(&core_lock);
-	res = idr_alloc(&i2c_adapter_idr, adapter,
-			__i2c_first_dynamic_bus_num, 0, GFP_KERNEL);
+	id = idr_alloc(&i2c_adapter_idr, adapter,
+		       __i2c_first_dynamic_bus_num, 0, GFP_KERNEL);
 	mutex_unlock(&core_lock);
-	if (res < 0)
-		return res;
+	if (id < 0)
+		return id;
+
+	adapter->nr = id;
 
-	adapter->nr = res;
 	return i2c_register_adapter(adapter);
 }
 EXPORT_SYMBOL(i2c_add_adapter);

Re: [PATCH -mm] i2c: style cleanups after idr_alloc() conversion

[Tejun Heo]

On Tue, Feb 12, 2013 at 09:34:14AM -0800, Tejun Heo wrote:
> Style cleanups suggested by Wolfram.
> 
> * s/res/id/ in i2c_add_numbered_adapter() so that it matches
>   i2c_add_adapter().
> 
> * Add a blank line before return in i2c_add_numbered_adapter().
> 
> This patch is purely cosmetic.
> 
> Signed-off-by: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> Cc: Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>

JFYI, got a permanent delivery failure for w.sang-bIcnvbaLZ9NtG/3OEaXNhw@public.gmane.org
Does anyone in i2c circle know other contact points?  If so, please
ping him about it.

Thanks!

-- 
tejun

Re: [PATCH -mm] i2c: style cleanups after idr_alloc() conversion

[Jean Delvare]

On Tue, 12 Feb 2013 09:36:48 -0800, Tejun Heo wrote:
> On Tue, Feb 12, 2013 at 09:34:14AM -0800, Tejun Heo wrote:
> > Style cleanups suggested by Wolfram.
> > 
> > * s/res/id/ in i2c_add_numbered_adapter() so that it matches
> >   i2c_add_adapter().
> > 
> > * Add a blank line before return in i2c_add_numbered_adapter().
> > 
> > This patch is purely cosmetic.
> > 
> > Signed-off-by: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> > Cc: Wolfram Sang <w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
> 
> JFYI, got a permanent delivery failure for w.sang-bIcnvbaLZ9NtG/3OEaXNhw@public.gmane.org
> Does anyone in i2c circle know other contact points?  If so, please
> ping him about it.

See the updated Cc list :)

-- 
Jean Delvare

Re: [PATCH -mm] i2c: style cleanups after idr_alloc() conversion

[Wolfram Sang]

On Tue, Feb 12, 2013 at 09:34:14AM -0800, Tejun Heo wrote:
> Style cleanups suggested by Wolfram.
> 
> * s/res/id/ in i2c_add_numbered_adapter() so that it matches
>   i2c_add_adapter().
> 
> * Add a blank line before return in i2c_add_numbered_adapter().
> 
> This patch is purely cosmetic.
> 
> Signed-off-by: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>

Acked-by: Wolfram Sang <wolfram-z923LK4zBo2bacvFa/9K2g@public.gmane.org>

Would be nice to fold this patch into the previous one, if possible.