[PATCH 0/4] omap: mailbox: cleanup & simplify

[PATCH 0/4] omap: mailbox: cleanup & simplify

[Ohad Ben-Cohen]

A few simple patches that cleanup and simplifies mailbox.
The last patch is the most interesting -
It converts mailbox to use kfifo as the underlying
queueing implementation instead of using the block API.
There're also additional performance patches on the way, we
are internally testing them now.

Please review and let me know your comments.

Thanks,

Ohad Ben-Cohen (4):
  omap: mailbox cleanup: convert rwlocks to spinlock
  omap: mailbox cleanup: split MODULE_AUTHOR line
  omap: mailbox: fix reverse likeliness
  omap: mailbox: convert block api to kfifo

 arch/arm/mach-omap2/mailbox.c             |    3 +-
 arch/arm/plat-omap/include/plat/mailbox.h |    5 +-
 arch/arm/plat-omap/mailbox.c              |  135 +++++++++++++----------------
 3 files changed, 68 insertions(+), 75 deletions(-)

[PATCH 1/4] omap: mailbox cleanup: convert rwlocks to spinlock

[Ohad Ben-Cohen]

rwlocks are slower and have potential starvation issues so spinlocks are
generally preferred

Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
---
 arch/arm/plat-omap/mailbox.c |   20 ++++++++++----------
 1 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/arch/arm/plat-omap/mailbox.c b/arch/arm/plat-omap/mailbox.c
index 08a2df7..d73d51a 100644
--- a/arch/arm/plat-omap/mailbox.c
+++ b/arch/arm/plat-omap/mailbox.c
@@ -31,7 +31,7 @@
 
 static struct workqueue_struct *mboxd;
 static struct omap_mbox *mboxes;
-static DEFINE_RWLOCK(mboxes_lock);
+static DEFINE_SPINLOCK(mboxes_lock);
 
 static int mbox_configured;
 
@@ -330,14 +330,14 @@ struct omap_mbox *omap_mbox_get(const char *name)
 	struct omap_mbox *mbox;
 	int ret;
 
-	read_lock(&mboxes_lock);
+	spin_lock(&mboxes_lock);
 	mbox = *(find_mboxes(name));
 	if (mbox == NULL) {
-		read_unlock(&mboxes_lock);
+		spin_unlock(&mboxes_lock);
 		return ERR_PTR(-ENOENT);
 	}
 
-	read_unlock(&mboxes_lock);
+	spin_unlock(&mboxes_lock);
 
 	ret = omap_mbox_startup(mbox);
 	if (ret)
@@ -363,15 +363,15 @@ int omap_mbox_register(struct device *parent, struct omap_mbox *mbox)
 	if (mbox->next)
 		return -EBUSY;
 
-	write_lock(&mboxes_lock);
+	spin_lock(&mboxes_lock);
 	tmp = find_mboxes(mbox->name);
 	if (*tmp) {
 		ret = -EBUSY;
-		write_unlock(&mboxes_lock);
+		spin_unlock(&mboxes_lock);
 		goto err_find;
 	}
 	*tmp = mbox;
-	write_unlock(&mboxes_lock);
+	spin_unlock(&mboxes_lock);
 
 	return 0;
 
@@ -384,18 +384,18 @@ int omap_mbox_unregister(struct omap_mbox *mbox)
 {
 	struct omap_mbox **tmp;
 
-	write_lock(&mboxes_lock);
+	spin_lock(&mboxes_lock);
 	tmp = &mboxes;
 	while (*tmp) {
 		if (mbox == *tmp) {
 			*tmp = mbox->next;
 			mbox->next = NULL;
-			write_unlock(&mboxes_lock);
+			spin_unlock(&mboxes_lock);
 			return 0;
 		}
 		tmp = &(*tmp)->next;
 	}
-	write_unlock(&mboxes_lock);
+	spin_unlock(&mboxes_lock);
 
 	return -EINVAL;
 }
-- 
1.6.3.3

Re: [PATCH 1/4] omap: mailbox cleanup: convert rwlocks to spinlock

[Hiroshi DOYU]

Hi Ohad,

From: ext Ohad Ben-Cohen <ohad@wizery.com>
Subject: [PATCH 1/4] omap: mailbox cleanup: convert rwlocks to spinlock
Date: Tue, 27 Apr 2010 19:56:19 +0200

> rwlocks are slower and have potential starvation issues so spinlocks are
> generally preferred

Would it be possible to explain the above a bit more?

Re: [PATCH 1/4] omap: mailbox cleanup: convert rwlocks to spinlock

[Ohad Ben-Cohen]

Hi Hiroshi,

On Wed, Apr 28, 2010 at 10:50 AM, Hiroshi DOYU <Hiroshi.DOYU@nokia.com> wrote:
> Hi Ohad,
>
> From: ext Ohad Ben-Cohen <ohad@wizery.com>
> Subject: [PATCH 1/4] omap: mailbox cleanup: convert rwlocks to spinlock
> Date: Tue, 27 Apr 2010 19:56:19 +0200
>
>> rwlocks are slower and have potential starvation issues so spinlocks are
>> generally preferred
>
> Would it be possible to explain the above a bit more?

Sure, sorry for the laconic description.

Jonathan Corbet wrote a nice summary about this:
http://lwn.net/Articles/364583/

We could switch to rcu, but it's really an overkill because we don't really
have a high bandwidth of readers (omap_mbox_get is not being called
so much).

The only disadvantage of a plain spinlock is that readers now will have
to wait in the line, but since omap_mbox_get isn't called so frequently,
I guess that by moving to spinlocks the average performance will actually
increase (since spinlocks are faster and most likely there will not be
multiple concurrent calls to omap_mbox_get).

Anyway I only consider this as a cleanup and not really a performance
issue, as mboxes_lock is not really on a hot path.

Thanks,
Ohad.


>

RE: [PATCH 1/4] omap: mailbox cleanup: convert rwlocks to spinlock

[Kanigeri, Hari]

Ohad, 

Looks like the conversion was missed in few places resulting in compile warnings.

Please see the below fix. Let me know if you agree with the change.

#########
[PATCH] omap: mailbox: rwlocks to spinlock: compilation fix

fixed the missed  rwlocks in few places resultion in following
compiler warning.

arch/arm/plat-omap/mailbox.c: In function 'omap_mbox_startup':
arch/arm/plat-omap/mailbox.c:246: warning: passing argument 1 of '_raw_write_lock' from incompatible pointer type
arch/arm/plat-omap/mailbox.c:251: warning: passing argument 1 of '_raw_write_unlock' from incompatible pointer type
arch/arm/plat-omap/mailbox.c:255: warning: passing argument 1 of '_raw_write_unlock' from incompatible pointer type
arch/arm/plat-omap/mailbox.c: In function 'omap_mbox_fini':
arch/arm/plat-omap/mailbox.c:301: warning: passing argument 1 of '_raw_write_lock' from incompatible pointer type
arch/arm/plat-omap/mailbox.c:306: warning: passing argument 1 of '_raw_write_unlock' from incompatible pointer type

Signed-off-by: Hari Kanigeri <h-kanigeri2@ti.com>
---
 arch/arm/plat-omap/mailbox.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/arm/plat-omap/mailbox.c b/arch/arm/plat-omap/mailbox.c
index 27a8d98..d6a700d 100644
--- a/arch/arm/plat-omap/mailbox.c
+++ b/arch/arm/plat-omap/mailbox.c
@@ -243,16 +243,16 @@ static int omap_mbox_startup(struct omap_mbox *mbox)
        struct omap_mbox_queue *mq;

        if (likely(mbox->ops->startup)) {
-               write_lock(&mboxes_lock);
+               spin_lock(&mboxes_lock);
                if (!mbox_configured)
                        ret = mbox->ops->startup(mbox);

                if (unlikely(ret)) {
-                       write_unlock(&mboxes_lock);
+                       spin_unlock(&mboxes_lock);
                        return ret;
                }
                mbox_configured++;
-               write_unlock(&mboxes_lock);
+               spin_unlock(&mboxes_lock);
        }

        ret = request_irq(mbox->irq, mbox_interrupt, IRQF_SHARED,
@@ -298,12 +298,12 @@ static void omap_mbox_fini(struct omap_mbox *mbox)
        free_irq(mbox->irq, mbox);

        if (likely(mbox->ops->shutdown)) {
-               write_lock(&mboxes_lock);
+               spin_lock(&mboxes_lock);
                if (mbox_configured > 0)
                        mbox_configured--;
                if (!mbox_configured)
                        mbox->ops->shutdown(mbox);
-               write_unlock(&mboxes_lock);
+               spin_unlock(&mboxes_lock);
        }
 }

--

################

> -----Original Message-----
> From: Ohad Ben-Cohen [mailto:ohad@wizery.com] 
> Sent: Tuesday, April 27, 2010 12:56 PM
> To: linux-omap@vger.kernel.org
> Cc: Kanigeri, Hari; Hiroshi Doyu; Ohad Ben-Cohen
> Subject: [PATCH 1/4] omap: mailbox cleanup: convert rwlocks 
> to spinlock
> 
> rwlocks are slower and have potential starvation issues so 
> spinlocks are generally preferred
> 
> Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
> ---
>  arch/arm/plat-omap/mailbox.c |   20 ++++++++++----------
>  1 files changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/arm/plat-omap/mailbox.c 
> b/arch/arm/plat-omap/mailbox.c index 08a2df7..d73d51a 100644
> --- a/arch/arm/plat-omap/mailbox.c
> +++ b/arch/arm/plat-omap/mailbox.c
> @@ -31,7 +31,7 @@
>  
>  static struct workqueue_struct *mboxd;
>  static struct omap_mbox *mboxes;
> -static DEFINE_RWLOCK(mboxes_lock);
> +static DEFINE_SPINLOCK(mboxes_lock);
>  
>  static int mbox_configured;
>  
> @@ -330,14 +330,14 @@ struct omap_mbox *omap_mbox_get(const 
> char *name)
>  	struct omap_mbox *mbox;
>  	int ret;
>  
> -	read_lock(&mboxes_lock);
> +	spin_lock(&mboxes_lock);
>  	mbox = *(find_mboxes(name));
>  	if (mbox == NULL) {
> -		read_unlock(&mboxes_lock);
> +		spin_unlock(&mboxes_lock);
>  		return ERR_PTR(-ENOENT);
>  	}
>  
> -	read_unlock(&mboxes_lock);
> +	spin_unlock(&mboxes_lock);
>  
>  	ret = omap_mbox_startup(mbox);
>  	if (ret)
> @@ -363,15 +363,15 @@ int omap_mbox_register(struct device 
> *parent, struct omap_mbox *mbox)
>  	if (mbox->next)
>  		return -EBUSY;
>  
> -	write_lock(&mboxes_lock);
> +	spin_lock(&mboxes_lock);
>  	tmp = find_mboxes(mbox->name);
>  	if (*tmp) {
>  		ret = -EBUSY;
> -		write_unlock(&mboxes_lock);
> +		spin_unlock(&mboxes_lock);
>  		goto err_find;
>  	}
>  	*tmp = mbox;
> -	write_unlock(&mboxes_lock);
> +	spin_unlock(&mboxes_lock);
>  
>  	return 0;
>  
> @@ -384,18 +384,18 @@ int omap_mbox_unregister(struct 
> omap_mbox *mbox)  {
>  	struct omap_mbox **tmp;
>  
> -	write_lock(&mboxes_lock);
> +	spin_lock(&mboxes_lock);
>  	tmp = &mboxes;
>  	while (*tmp) {
>  		if (mbox == *tmp) {
>  			*tmp = mbox->next;
>  			mbox->next = NULL;
> -			write_unlock(&mboxes_lock);
> +			spin_unlock(&mboxes_lock);
>  			return 0;
>  		}
>  		tmp = &(*tmp)->next;
>  	}
> -	write_unlock(&mboxes_lock);
> +	spin_unlock(&mboxes_lock);
>  
>  	return -EINVAL;
>  }
> --
> 1.6.3.3
> 
> 

Re: [PATCH 1/4] omap: mailbox cleanup: convert rwlocks to spinlock

[Ohad Ben-Cohen]

Hi Hari,

On Thu, Apr 29, 2010 at 3:44 PM, Kanigeri, Hari <h-kanigeri2@ti.com> wrote:
> Ohad,
>
> Looks like the conversion was missed in few places resulting in compile warnings.

Thanks for pointing that out - that's really strange, it somehow
slipped in the rebase.

The interesting part is that because you compile for OMAP4 (SMP),
you got to see the warnings, while I didn't because I compiled for OMAP3
(in the UP case there's no real locking and both types of locks are
actually the same).

>
> Please see the below fix. Let me know if you agree with the change.

Sure. I'll add that missing part back together with the review comments,
and submit a v2 patchset.

Thanks again,
Ohad.


>
> #########
> [PATCH] omap: mailbox: rwlocks to spinlock: compilation fix
>
> fixed the missed  rwlocks in few places resultion in following
> compiler warning.
>
> arch/arm/plat-omap/mailbox.c: In function 'omap_mbox_startup':
> arch/arm/plat-omap/mailbox.c:246: warning: passing argument 1 of '_raw_write_lock' from incompatible pointer type
> arch/arm/plat-omap/mailbox.c:251: warning: passing argument 1 of '_raw_write_unlock' from incompatible pointer type
> arch/arm/plat-omap/mailbox.c:255: warning: passing argument 1 of '_raw_write_unlock' from incompatible pointer type
> arch/arm/plat-omap/mailbox.c: In function 'omap_mbox_fini':
> arch/arm/plat-omap/mailbox.c:301: warning: passing argument 1 of '_raw_write_lock' from incompatible pointer type
> arch/arm/plat-omap/mailbox.c:306: warning: passing argument 1 of '_raw_write_unlock' from incompatible pointer type
>
> Signed-off-by: Hari Kanigeri <h-kanigeri2@ti.com>
> ---
>  arch/arm/plat-omap/mailbox.c |   10 +++++-----
>  1 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm/plat-omap/mailbox.c b/arch/arm/plat-omap/mailbox.c
> index 27a8d98..d6a700d 100644
> --- a/arch/arm/plat-omap/mailbox.c
> +++ b/arch/arm/plat-omap/mailbox.c
> @@ -243,16 +243,16 @@ static int omap_mbox_startup(struct omap_mbox *mbox)
>        struct omap_mbox_queue *mq;
>
>        if (likely(mbox->ops->startup)) {
> -               write_lock(&mboxes_lock);
> +               spin_lock(&mboxes_lock);
>                if (!mbox_configured)
>                        ret = mbox->ops->startup(mbox);
>
>                if (unlikely(ret)) {
> -                       write_unlock(&mboxes_lock);
> +                       spin_unlock(&mboxes_lock);
>                        return ret;
>                }
>                mbox_configured++;
> -               write_unlock(&mboxes_lock);
> +               spin_unlock(&mboxes_lock);
>        }
>
>        ret = request_irq(mbox->irq, mbox_interrupt, IRQF_SHARED,
> @@ -298,12 +298,12 @@ static void omap_mbox_fini(struct omap_mbox *mbox)
>        free_irq(mbox->irq, mbox);
>
>        if (likely(mbox->ops->shutdown)) {
> -               write_lock(&mboxes_lock);
> +               spin_lock(&mboxes_lock);
>                if (mbox_configured > 0)
>                        mbox_configured--;
>                if (!mbox_configured)
>                        mbox->ops->shutdown(mbox);
> -               write_unlock(&mboxes_lock);
> +               spin_unlock(&mboxes_lock);
>        }
>  }
>
> --
>
> ################
>
>> -----Original Message-----
>> From: Ohad Ben-Cohen [mailto:ohad@wizery.com]
>> Sent: Tuesday, April 27, 2010 12:56 PM
>> To: linux-omap@vger.kernel.org
>> Cc: Kanigeri, Hari; Hiroshi Doyu; Ohad Ben-Cohen
>> Subject: [PATCH 1/4] omap: mailbox cleanup: convert rwlocks
>> to spinlock
>>
>> rwlocks are slower and have potential starvation issues so
>> spinlocks are generally preferred
>>
>> Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
>> ---
>>  arch/arm/plat-omap/mailbox.c |   20 ++++++++++----------
>>  1 files changed, 10 insertions(+), 10 deletions(-)
>>
>> diff --git a/arch/arm/plat-omap/mailbox.c
>> b/arch/arm/plat-omap/mailbox.c index 08a2df7..d73d51a 100644
>> --- a/arch/arm/plat-omap/mailbox.c
>> +++ b/arch/arm/plat-omap/mailbox.c
>> @@ -31,7 +31,7 @@
>>
>>  static struct workqueue_struct *mboxd;
>>  static struct omap_mbox *mboxes;
>> -static DEFINE_RWLOCK(mboxes_lock);
>> +static DEFINE_SPINLOCK(mboxes_lock);
>>
>>  static int mbox_configured;
>>
>> @@ -330,14 +330,14 @@ struct omap_mbox *omap_mbox_get(const
>> char *name)
>>       struct omap_mbox *mbox;
>>       int ret;
>>
>> -     read_lock(&mboxes_lock);
>> +     spin_lock(&mboxes_lock);
>>       mbox = *(find_mboxes(name));
>>       if (mbox == NULL) {
>> -             read_unlock(&mboxes_lock);
>> +             spin_unlock(&mboxes_lock);
>>               return ERR_PTR(-ENOENT);
>>       }
>>
>> -     read_unlock(&mboxes_lock);
>> +     spin_unlock(&mboxes_lock);
>>
>>       ret = omap_mbox_startup(mbox);
>>       if (ret)
>> @@ -363,15 +363,15 @@ int omap_mbox_register(struct device
>> *parent, struct omap_mbox *mbox)
>>       if (mbox->next)
>>               return -EBUSY;
>>
>> -     write_lock(&mboxes_lock);
>> +     spin_lock(&mboxes_lock);
>>       tmp = find_mboxes(mbox->name);
>>       if (*tmp) {
>>               ret = -EBUSY;
>> -             write_unlock(&mboxes_lock);
>> +             spin_unlock(&mboxes_lock);
>>               goto err_find;
>>       }
>>       *tmp = mbox;
>> -     write_unlock(&mboxes_lock);
>> +     spin_unlock(&mboxes_lock);
>>
>>       return 0;
>>
>> @@ -384,18 +384,18 @@ int omap_mbox_unregister(struct
>> omap_mbox *mbox)  {
>>       struct omap_mbox **tmp;
>>
>> -     write_lock(&mboxes_lock);
>> +     spin_lock(&mboxes_lock);
>>       tmp = &mboxes;
>>       while (*tmp) {
>>               if (mbox == *tmp) {
>>                       *tmp = mbox->next;
>>                       mbox->next = NULL;
>> -                     write_unlock(&mboxes_lock);
>> +                     spin_unlock(&mboxes_lock);
>>                       return 0;
>>               }
>>               tmp = &(*tmp)->next;
>>       }
>> -     write_unlock(&mboxes_lock);
>> +     spin_unlock(&mboxes_lock);
>>
>>       return -EINVAL;
>>  }
>> --
>> 1.6.3.3
>>
>>
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Re: [PATCH 1/4] omap: mailbox cleanup: convert rwlocks to spinlock

[Ohad Ben-Cohen]

On Thu, Apr 29, 2010 at 4:14 PM, Ohad Ben-Cohen <ohad@wizery.com> wrote:
> Hi Hari,
>
> On Thu, Apr 29, 2010 at 3:44 PM, Kanigeri, Hari <h-kanigeri2@ti.com> wrote:
>> Ohad,
>>
>> Looks like the conversion was missed in few places resulting in compile warnings.
>
> Thanks for pointing that out - that's really strange, it somehow
> slipped in the rebase.
>
> The interesting part is that because you compile for OMAP4 (SMP),
> you got to see the warnings, while I didn't because I compiled for OMAP3
> (in the UP case there's no real locking and both types of locks are
> actually the same).
>
>>
>> Please see the below fix. Let me know if you agree with the change.
>
> Sure. I'll add that missing part back together with the review comments,
> and submit a v2 patchset.

If anyone needs the complete patch now, the original can be found here:

http://dev.omapzoom.org/?p=tisyslink/kernel-syslink.git;a=commitdiff;h=8da0385a57cc470ee0a013b164fd3d2438455e79

Thanks,
Ohad.
>
> Thanks again,
> Ohad.
>
>
>>
>> #########
>> [PATCH] omap: mailbox: rwlocks to spinlock: compilation fix
>>
>> fixed the missed  rwlocks in few places resultion in following
>> compiler warning.
>>
>> arch/arm/plat-omap/mailbox.c: In function 'omap_mbox_startup':
>> arch/arm/plat-omap/mailbox.c:246: warning: passing argument 1 of '_raw_write_lock' from incompatible pointer type
>> arch/arm/plat-omap/mailbox.c:251: warning: passing argument 1 of '_raw_write_unlock' from incompatible pointer type
>> arch/arm/plat-omap/mailbox.c:255: warning: passing argument 1 of '_raw_write_unlock' from incompatible pointer type
>> arch/arm/plat-omap/mailbox.c: In function 'omap_mbox_fini':
>> arch/arm/plat-omap/mailbox.c:301: warning: passing argument 1 of '_raw_write_lock' from incompatible pointer type
>> arch/arm/plat-omap/mailbox.c:306: warning: passing argument 1 of '_raw_write_unlock' from incompatible pointer type
>>
>> Signed-off-by: Hari Kanigeri <h-kanigeri2@ti.com>
>> ---
>>  arch/arm/plat-omap/mailbox.c |   10 +++++-----
>>  1 files changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/arch/arm/plat-omap/mailbox.c b/arch/arm/plat-omap/mailbox.c
>> index 27a8d98..d6a700d 100644
>> --- a/arch/arm/plat-omap/mailbox.c
>> +++ b/arch/arm/plat-omap/mailbox.c
>> @@ -243,16 +243,16 @@ static int omap_mbox_startup(struct omap_mbox *mbox)
>>        struct omap_mbox_queue *mq;
>>
>>        if (likely(mbox->ops->startup)) {
>> -               write_lock(&mboxes_lock);
>> +               spin_lock(&mboxes_lock);
>>                if (!mbox_configured)
>>                        ret = mbox->ops->startup(mbox);
>>
>>                if (unlikely(ret)) {
>> -                       write_unlock(&mboxes_lock);
>> +                       spin_unlock(&mboxes_lock);
>>                        return ret;
>>                }
>>                mbox_configured++;
>> -               write_unlock(&mboxes_lock);
>> +               spin_unlock(&mboxes_lock);
>>        }
>>
>>        ret = request_irq(mbox->irq, mbox_interrupt, IRQF_SHARED,
>> @@ -298,12 +298,12 @@ static void omap_mbox_fini(struct omap_mbox *mbox)
>>        free_irq(mbox->irq, mbox);
>>
>>        if (likely(mbox->ops->shutdown)) {
>> -               write_lock(&mboxes_lock);
>> +               spin_lock(&mboxes_lock);
>>                if (mbox_configured > 0)
>>                        mbox_configured--;
>>                if (!mbox_configured)
>>                        mbox->ops->shutdown(mbox);
>> -               write_unlock(&mboxes_lock);
>> +               spin_unlock(&mboxes_lock);
>>        }
>>  }
>>
>> --
>>
>> ################
>>
>>> -----Original Message-----
>>> From: Ohad Ben-Cohen [mailto:ohad@wizery.com]
>>> Sent: Tuesday, April 27, 2010 12:56 PM
>>> To: linux-omap@vger.kernel.org
>>> Cc: Kanigeri, Hari; Hiroshi Doyu; Ohad Ben-Cohen
>>> Subject: [PATCH 1/4] omap: mailbox cleanup: convert rwlocks
>>> to spinlock
>>>
>>> rwlocks are slower and have potential starvation issues so
>>> spinlocks are generally preferred
>>>
>>> Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
>>> ---
>>>  arch/arm/plat-omap/mailbox.c |   20 ++++++++++----------
>>>  1 files changed, 10 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/arch/arm/plat-omap/mailbox.c
>>> b/arch/arm/plat-omap/mailbox.c index 08a2df7..d73d51a 100644
>>> --- a/arch/arm/plat-omap/mailbox.c
>>> +++ b/arch/arm/plat-omap/mailbox.c
>>> @@ -31,7 +31,7 @@
>>>
>>>  static struct workqueue_struct *mboxd;
>>>  static struct omap_mbox *mboxes;
>>> -static DEFINE_RWLOCK(mboxes_lock);
>>> +static DEFINE_SPINLOCK(mboxes_lock);
>>>
>>>  static int mbox_configured;
>>>
>>> @@ -330,14 +330,14 @@ struct omap_mbox *omap_mbox_get(const
>>> char *name)
>>>       struct omap_mbox *mbox;
>>>       int ret;
>>>
>>> -     read_lock(&mboxes_lock);
>>> +     spin_lock(&mboxes_lock);
>>>       mbox = *(find_mboxes(name));
>>>       if (mbox == NULL) {
>>> -             read_unlock(&mboxes_lock);
>>> +             spin_unlock(&mboxes_lock);
>>>               return ERR_PTR(-ENOENT);
>>>       }
>>>
>>> -     read_unlock(&mboxes_lock);
>>> +     spin_unlock(&mboxes_lock);
>>>
>>>       ret = omap_mbox_startup(mbox);
>>>       if (ret)
>>> @@ -363,15 +363,15 @@ int omap_mbox_register(struct device
>>> *parent, struct omap_mbox *mbox)
>>>       if (mbox->next)
>>>               return -EBUSY;
>>>
>>> -     write_lock(&mboxes_lock);
>>> +     spin_lock(&mboxes_lock);
>>>       tmp = find_mboxes(mbox->name);
>>>       if (*tmp) {
>>>               ret = -EBUSY;
>>> -             write_unlock(&mboxes_lock);
>>> +             spin_unlock(&mboxes_lock);
>>>               goto err_find;
>>>       }
>>>       *tmp = mbox;
>>> -     write_unlock(&mboxes_lock);
>>> +     spin_unlock(&mboxes_lock);
>>>
>>>       return 0;
>>>
>>> @@ -384,18 +384,18 @@ int omap_mbox_unregister(struct
>>> omap_mbox *mbox)  {
>>>       struct omap_mbox **tmp;
>>>
>>> -     write_lock(&mboxes_lock);
>>> +     spin_lock(&mboxes_lock);
>>>       tmp = &mboxes;
>>>       while (*tmp) {
>>>               if (mbox == *tmp) {
>>>                       *tmp = mbox->next;
>>>                       mbox->next = NULL;
>>> -                     write_unlock(&mboxes_lock);
>>> +                     spin_unlock(&mboxes_lock);
>>>                       return 0;
>>>               }
>>>               tmp = &(*tmp)->next;
>>>       }
>>> -     write_unlock(&mboxes_lock);
>>> +     spin_unlock(&mboxes_lock);
>>>
>>>       return -EINVAL;
>>>  }
>>> --
>>> 1.6.3.3
>>>
>>>
>
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[PATCH 2/4] omap: mailbox cleanup: split MODULE_AUTHOR line

[Ohad Ben-Cohen]

use multiple MODULE_AUTHOR lines for multiple authors

Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
---
 arch/arm/mach-omap2/mailbox.c |    3 ++-
 arch/arm/plat-omap/mailbox.c  |    3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mach-omap2/mailbox.c b/arch/arm/mach-omap2/mailbox.c
index 318f363..763272c 100644
--- a/arch/arm/mach-omap2/mailbox.c
+++ b/arch/arm/mach-omap2/mailbox.c
@@ -486,5 +486,6 @@ module_exit(omap2_mbox_exit);
 
 MODULE_LICENSE("GPL v2");
 MODULE_DESCRIPTION("omap mailbox: omap2/3/4 architecture specific functions");
-MODULE_AUTHOR("Hiroshi DOYU <Hiroshi.DOYU@nokia.com>, Paul Mundt");
+MODULE_AUTHOR("Hiroshi DOYU <Hiroshi.DOYU@nokia.com>");
+MODULE_AUTHOR("Paul Mundt");
 MODULE_ALIAS("platform:"DRV_NAME);
diff --git a/arch/arm/plat-omap/mailbox.c b/arch/arm/plat-omap/mailbox.c
index d73d51a..8abf0e8 100644
--- a/arch/arm/plat-omap/mailbox.c
+++ b/arch/arm/plat-omap/mailbox.c
@@ -419,4 +419,5 @@ module_exit(omap_mbox_exit);
 
 MODULE_LICENSE("GPL v2");
 MODULE_DESCRIPTION("omap mailbox: interrupt driven messaging");
-MODULE_AUTHOR("Toshihiro Kobayashi and Hiroshi DOYU");
+MODULE_AUTHOR("Toshihiro Kobayashi");
+MODULE_AUTHOR("Hiroshi DOYU");
-- 
1.6.3.3

[PATCH 3/4] omap: mailbox: fix reverse likeliness

[Ohad Ben-Cohen]

Fix reverse likeliness

Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
---
 arch/arm/plat-omap/mailbox.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm/plat-omap/mailbox.c b/arch/arm/plat-omap/mailbox.c
index 8abf0e8..72b17ad 100644
--- a/arch/arm/plat-omap/mailbox.c
+++ b/arch/arm/plat-omap/mailbox.c
@@ -290,7 +290,7 @@ static int omap_mbox_startup(struct omap_mbox *mbox)
  fail_alloc_txq:
 	free_irq(mbox->irq, mbox);
  fail_request_irq:
-	if (unlikely(mbox->ops->shutdown))
+	if (likely(mbox->ops->shutdown))
 		mbox->ops->shutdown(mbox);
 
 	return ret;
@@ -303,7 +303,7 @@ static void omap_mbox_fini(struct omap_mbox *mbox)
 
 	free_irq(mbox->irq, mbox);
 
-	if (unlikely(mbox->ops->shutdown)) {
+	if (likely(mbox->ops->shutdown)) {
 		write_lock(&mboxes_lock);
 		if (mbox_configured > 0)
 			mbox_configured--;
-- 
1.6.3.3

[PATCH 4/4] omap: mailbox: convert block api to kfifo

[Ohad Ben-Cohen]

The underlying buffering implementation of mailbox
is converted from block API to kfifo due to the simplicity
and speed of kfifo.

Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
Signed-off-by: Hari Kanigeri <h-kanigeri2@ti.com>
---
 arch/arm/plat-omap/include/plat/mailbox.h |    5 +-
 arch/arm/plat-omap/mailbox.c              |  108 +++++++++++++----------------
 2 files changed, 52 insertions(+), 61 deletions(-)

diff --git a/arch/arm/plat-omap/include/plat/mailbox.h b/arch/arm/plat-omap/include/plat/mailbox.h
index 729166b..014cc58 100644
--- a/arch/arm/plat-omap/include/plat/mailbox.h
+++ b/arch/arm/plat-omap/include/plat/mailbox.h
@@ -7,6 +7,7 @@
 #include <linux/workqueue.h>
 #include <linux/blkdev.h>
 #include <linux/interrupt.h>
+#include <linux/kfifo.h>
 
 typedef u32 mbox_msg_t;
 struct omap_mbox;
@@ -19,6 +20,8 @@ typedef int __bitwise omap_mbox_type_t;
 #define OMAP_MBOX_TYPE1 ((__force omap_mbox_type_t) 1)
 #define OMAP_MBOX_TYPE2 ((__force omap_mbox_type_t) 2)
 
+#define MBOX_KFIFO_SIZE	(256)
+
 struct omap_mbox_ops {
 	omap_mbox_type_t	type;
 	int		(*startup)(struct omap_mbox *mbox);
@@ -42,7 +45,7 @@ struct omap_mbox_ops {
 
 struct omap_mbox_queue {
 	spinlock_t		lock;
-	struct request_queue	*queue;
+	struct kfifo		fifo;
 	struct work_struct	work;
 	struct tasklet_struct	tasklet;
 	int	(*callback)(void *);
diff --git a/arch/arm/plat-omap/mailbox.c b/arch/arm/plat-omap/mailbox.c
index 72b17ad..b1324f3 100644
--- a/arch/arm/plat-omap/mailbox.c
+++ b/arch/arm/plat-omap/mailbox.c
@@ -26,6 +26,7 @@
 #include <linux/device.h>
 #include <linux/delay.h>
 #include <linux/slab.h>
+#include <linux/kfifo.h>
 
 #include <plat/mailbox.h>
 
@@ -67,7 +68,7 @@ static inline int is_mbox_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
 /*
  * message sender
  */
-static int __mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
+static int __mbox_poll_for_space(struct omap_mbox *mbox)
 {
 	int ret = 0, i = 1000;
 
@@ -78,49 +79,54 @@ static int __mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
 			return -1;
 		udelay(1);
 	}
-	mbox_fifo_write(mbox, msg);
 	return ret;
 }
 
-
 int omap_mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
 {
+	struct omap_mbox_queue *mq = mbox->txq;
+	int ret = 0, len;
 
-	struct request *rq;
-	struct request_queue *q = mbox->txq->queue;
+	spin_lock(&mq->lock);
 
-	rq = blk_get_request(q, WRITE, GFP_ATOMIC);
-	if (unlikely(!rq))
-		return -ENOMEM;
+	if (kfifo_avail(&mq->fifo) < sizeof(msg)) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	len = kfifo_in(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
+	if (unlikely(len != sizeof(msg))) {
+		pr_err("%s: kfifo_in anomaly\n", __func__);
+		ret = -ENOMEM;
+	}
 
-	blk_insert_request(q, rq, 0, (void *) msg);
 	tasklet_schedule(&mbox->txq->tasklet);
 
-	return 0;
+out:
+	spin_unlock(&mq->lock);
+	return ret;
 }
 EXPORT_SYMBOL(omap_mbox_msg_send);
 
 static void mbox_tx_tasklet(unsigned long tx_data)
 {
-	int ret;
-	struct request *rq;
 	struct omap_mbox *mbox = (struct omap_mbox *)tx_data;
-	struct request_queue *q = mbox->txq->queue;
-
-	while (1) {
-
-		rq = blk_fetch_request(q);
-
-		if (!rq)
-			break;
+	struct omap_mbox_queue *mq = mbox->txq;
+	mbox_msg_t msg;
+	int ret;
 
-		ret = __mbox_msg_send(mbox, (mbox_msg_t)rq->special);
-		if (ret) {
+	while (kfifo_len(&mq->fifo)) {
+		if (__mbox_poll_for_space(mbox)) {
 			omap_mbox_enable_irq(mbox, IRQ_TX);
-			blk_requeue_request(q, rq);
-			return;
+			break;
 		}
-		blk_end_request_all(rq, 0);
+
+		ret = kfifo_out(&mq->fifo, (unsigned char *)&msg,
+								sizeof(msg));
+		if (unlikely(ret != sizeof(msg)))
+			pr_err("%s: kfifo_out anomaly\n", __func__);
+
+		mbox_fifo_write(mbox, msg);
 	}
 }
 
@@ -131,36 +137,22 @@ static void mbox_rx_work(struct work_struct *work)
 {
 	struct omap_mbox_queue *mq =
 			container_of(work, struct omap_mbox_queue, work);
-	struct omap_mbox *mbox = mq->queue->queuedata;
-	struct request_queue *q = mbox->rxq->queue;
-	struct request *rq;
 	mbox_msg_t msg;
-	unsigned long flags;
+	int len;
 
-	while (1) {
-		spin_lock_irqsave(q->queue_lock, flags);
-		rq = blk_fetch_request(q);
-		spin_unlock_irqrestore(q->queue_lock, flags);
-		if (!rq)
-			break;
+	while (kfifo_len(&mq->fifo) >= sizeof(msg)) {
+		len = kfifo_out(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
+		if (unlikely(len != sizeof(msg)))
+			pr_err("%s: kfifo_out anomaly detected\n", __func__);
 
-		msg = (mbox_msg_t)rq->special;
-		blk_end_request_all(rq, 0);
-		mbox->rxq->callback((void *)msg);
+		if (mq->callback)
+			mq->callback((void *)msg);
 	}
 }
 
 /*
  * Mailbox interrupt handler
  */
-static void mbox_txq_fn(struct request_queue *q)
-{
-}
-
-static void mbox_rxq_fn(struct request_queue *q)
-{
-}
-
 static void __mbox_tx_interrupt(struct omap_mbox *mbox)
 {
 	omap_mbox_disable_irq(mbox, IRQ_TX);
@@ -170,19 +162,20 @@ static void __mbox_tx_interrupt(struct omap_mbox *mbox)
 
 static void __mbox_rx_interrupt(struct omap_mbox *mbox)
 {
-	struct request *rq;
+	struct omap_mbox_queue *mq = mbox->rxq;
 	mbox_msg_t msg;
-	struct request_queue *q = mbox->rxq->queue;
+	int len;
 
 	while (!mbox_fifo_empty(mbox)) {
-		rq = blk_get_request(q, WRITE, GFP_ATOMIC);
-		if (unlikely(!rq))
+		if (unlikely(kfifo_avail(&mq->fifo) < sizeof(msg)))
 			goto nomem;
 
 		msg = mbox_fifo_read(mbox);
 
 
-		blk_insert_request(q, rq, 0, (void *)msg);
+		len = kfifo_in(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
+		if (unlikely(len != sizeof(msg)))
+			pr_err("%s: kfifo_in anomaly detected\n", __func__);
 		if (mbox->ops->type == OMAP_MBOX_TYPE1)
 			break;
 	}
@@ -207,11 +200,9 @@ static irqreturn_t mbox_interrupt(int irq, void *p)
 }
 
 static struct omap_mbox_queue *mbox_queue_alloc(struct omap_mbox *mbox,
-					request_fn_proc *proc,
 					void (*work) (struct work_struct *),
 					void (*tasklet)(unsigned long))
 {
-	struct request_queue *q;
 	struct omap_mbox_queue *mq;
 
 	mq = kzalloc(sizeof(struct omap_mbox_queue), GFP_KERNEL);
@@ -220,11 +211,8 @@ static struct omap_mbox_queue *mbox_queue_alloc(struct omap_mbox *mbox,
 
 	spin_lock_init(&mq->lock);
 
-	q = blk_init_queue(proc, &mq->lock);
-	if (!q)
+	if (kfifo_alloc(&mq->fifo, MBOX_KFIFO_SIZE, GFP_KERNEL))
 		goto error;
-	q->queuedata = mbox;
-	mq->queue = q;
 
 	if (work)
 		INIT_WORK(&mq->work, work);
@@ -239,7 +227,7 @@ error:
 
 static void mbox_queue_free(struct omap_mbox_queue *q)
 {
-	blk_cleanup_queue(q->queue);
+	kfifo_free(&q->fifo);
 	kfree(q);
 }
 
@@ -269,14 +257,14 @@ static int omap_mbox_startup(struct omap_mbox *mbox)
 		goto fail_request_irq;
 	}
 
-	mq = mbox_queue_alloc(mbox, mbox_txq_fn, NULL, mbox_tx_tasklet);
+	mq = mbox_queue_alloc(mbox, NULL, mbox_tx_tasklet);
 	if (!mq) {
 		ret = -ENOMEM;
 		goto fail_alloc_txq;
 	}
 	mbox->txq = mq;
 
-	mq = mbox_queue_alloc(mbox, mbox_rxq_fn, mbox_rx_work, NULL);
+	mq = mbox_queue_alloc(mbox, mbox_rx_work, NULL);
 	if (!mq) {
 		ret = -ENOMEM;
 		goto fail_alloc_rxq;
-- 
1.6.3.3

Re: [PATCH 4/4] omap: mailbox: convert block api to kfifo

[Hiroshi DOYU]

Hi Ohad,

From: ext Ohad Ben-Cohen <ohad@wizery.com>
Subject: [PATCH 4/4] omap: mailbox: convert block api to kfifo
Date: Tue, 27 Apr 2010 19:56:22 +0200

> The underlying buffering implementation of mailbox
> is converted from block API to kfifo due to the simplicity
> and speed of kfifo.
> 
> Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
> Signed-off-by: Hari Kanigeri <h-kanigeri2@ti.com>
> ---
>  arch/arm/plat-omap/include/plat/mailbox.h |    5 +-
>  arch/arm/plat-omap/mailbox.c              |  108 +++++++++++++----------------
>  2 files changed, 52 insertions(+), 61 deletions(-)
> 
> diff --git a/arch/arm/plat-omap/include/plat/mailbox.h b/arch/arm/plat-omap/include/plat/mailbox.h
> index 729166b..014cc58 100644
> --- a/arch/arm/plat-omap/include/plat/mailbox.h
> +++ b/arch/arm/plat-omap/include/plat/mailbox.h
> @@ -7,6 +7,7 @@
>  #include <linux/workqueue.h>
>  #include <linux/blkdev.h>
>  #include <linux/interrupt.h>
> +#include <linux/kfifo.h>
>  
>  typedef u32 mbox_msg_t;
>  struct omap_mbox;
> @@ -19,6 +20,8 @@ typedef int __bitwise omap_mbox_type_t;
>  #define OMAP_MBOX_TYPE1 ((__force omap_mbox_type_t) 1)
>  #define OMAP_MBOX_TYPE2 ((__force omap_mbox_type_t) 2)
>  
> +#define MBOX_KFIFO_SIZE	(256)

Can this be a module parameter? Then, OEM could set their optimized value.

> +
>  struct omap_mbox_ops {
>  	omap_mbox_type_t	type;
>  	int		(*startup)(struct omap_mbox *mbox);
> @@ -42,7 +45,7 @@ struct omap_mbox_ops {
>  
>  struct omap_mbox_queue {
>  	spinlock_t		lock;
> -	struct request_queue	*queue;
> +	struct kfifo		fifo;
>  	struct work_struct	work;
>  	struct tasklet_struct	tasklet;
>  	int	(*callback)(void *);
> diff --git a/arch/arm/plat-omap/mailbox.c b/arch/arm/plat-omap/mailbox.c
> index 72b17ad..b1324f3 100644
> --- a/arch/arm/plat-omap/mailbox.c
> +++ b/arch/arm/plat-omap/mailbox.c
> @@ -26,6 +26,7 @@
>  #include <linux/device.h>
>  #include <linux/delay.h>
>  #include <linux/slab.h>
> +#include <linux/kfifo.h>
>  
>  #include <plat/mailbox.h>
>  
> @@ -67,7 +68,7 @@ static inline int is_mbox_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
>  /*
>   * message sender
>   */
> -static int __mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
> +static int __mbox_poll_for_space(struct omap_mbox *mbox)
>  {
>  	int ret = 0, i = 1000;
>  
> @@ -78,49 +79,54 @@ static int __mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
>  			return -1;
>  		udelay(1);
>  	}
> -	mbox_fifo_write(mbox, msg);
>  	return ret;
>  }
>  
> -
>  int omap_mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
>  {
> +	struct omap_mbox_queue *mq = mbox->txq;
> +	int ret = 0, len;
>  
> -	struct request *rq;
> -	struct request_queue *q = mbox->txq->queue;
> +	spin_lock(&mq->lock);
>  
> -	rq = blk_get_request(q, WRITE, GFP_ATOMIC);
> -	if (unlikely(!rq))
> -		return -ENOMEM;
> +	if (kfifo_avail(&mq->fifo) < sizeof(msg)) {
> +		ret = -ENOMEM;
> +		goto out;
> +	}
> +
> +	len = kfifo_in(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
> +	if (unlikely(len != sizeof(msg))) {
> +		pr_err("%s: kfifo_in anomaly\n", __func__);
> +		ret = -ENOMEM;
> +	}
>  
> -	blk_insert_request(q, rq, 0, (void *) msg);
>  	tasklet_schedule(&mbox->txq->tasklet);
>  
> -	return 0;
> +out:
> +	spin_unlock(&mq->lock);
> +	return ret;
>  }
>  EXPORT_SYMBOL(omap_mbox_msg_send);
>  
>  static void mbox_tx_tasklet(unsigned long tx_data)
>  {
> -	int ret;
> -	struct request *rq;
>  	struct omap_mbox *mbox = (struct omap_mbox *)tx_data;
> -	struct request_queue *q = mbox->txq->queue;
> -
> -	while (1) {
> -
> -		rq = blk_fetch_request(q);
> -
> -		if (!rq)
> -			break;
> +	struct omap_mbox_queue *mq = mbox->txq;
> +	mbox_msg_t msg;
> +	int ret;
>  
> -		ret = __mbox_msg_send(mbox, (mbox_msg_t)rq->special);
> -		if (ret) {
> +	while (kfifo_len(&mq->fifo)) {
> +		if (__mbox_poll_for_space(mbox)) {
>  			omap_mbox_enable_irq(mbox, IRQ_TX);
> -			blk_requeue_request(q, rq);
> -			return;
> +			break;
>  		}
> -		blk_end_request_all(rq, 0);
> +
> +		ret = kfifo_out(&mq->fifo, (unsigned char *)&msg,
> +								sizeof(msg));
> +		if (unlikely(ret != sizeof(msg)))
> +			pr_err("%s: kfifo_out anomaly\n", __func__);

No error recovery? same for other anomalies.

> +
> +		mbox_fifo_write(mbox, msg);
>  	}
>  }
>  
> @@ -131,36 +137,22 @@ static void mbox_rx_work(struct work_struct *work)
>  {
>  	struct omap_mbox_queue *mq =
>  			container_of(work, struct omap_mbox_queue, work);
> -	struct omap_mbox *mbox = mq->queue->queuedata;
> -	struct request_queue *q = mbox->rxq->queue;
> -	struct request *rq;
>  	mbox_msg_t msg;
> -	unsigned long flags;
> +	int len;
>  
> -	while (1) {
> -		spin_lock_irqsave(q->queue_lock, flags);
> -		rq = blk_fetch_request(q);
> -		spin_unlock_irqrestore(q->queue_lock, flags);
> -		if (!rq)
> -			break;
> +	while (kfifo_len(&mq->fifo) >= sizeof(msg)) {
> +		len = kfifo_out(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
> +		if (unlikely(len != sizeof(msg)))
> +			pr_err("%s: kfifo_out anomaly detected\n", __func__);
>  
> -		msg = (mbox_msg_t)rq->special;
> -		blk_end_request_all(rq, 0);
> -		mbox->rxq->callback((void *)msg);
> +		if (mq->callback)
> +			mq->callback((void *)msg);
>  	}
>  }
>  
>  /*
>   * Mailbox interrupt handler
>   */
> -static void mbox_txq_fn(struct request_queue *q)
> -{
> -}
> -
> -static void mbox_rxq_fn(struct request_queue *q)
> -{
> -}
> -
>  static void __mbox_tx_interrupt(struct omap_mbox *mbox)
>  {
>  	omap_mbox_disable_irq(mbox, IRQ_TX);
> @@ -170,19 +162,20 @@ static void __mbox_tx_interrupt(struct omap_mbox *mbox)
>  
>  static void __mbox_rx_interrupt(struct omap_mbox *mbox)
>  {
> -	struct request *rq;
> +	struct omap_mbox_queue *mq = mbox->rxq;
>  	mbox_msg_t msg;
> -	struct request_queue *q = mbox->rxq->queue;
> +	int len;
>  
>  	while (!mbox_fifo_empty(mbox)) {
> -		rq = blk_get_request(q, WRITE, GFP_ATOMIC);
> -		if (unlikely(!rq))
> +		if (unlikely(kfifo_avail(&mq->fifo) < sizeof(msg)))
>  			goto nomem;
>  
>  		msg = mbox_fifo_read(mbox);
>  
>  
> -		blk_insert_request(q, rq, 0, (void *)msg);
> +		len = kfifo_in(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
> +		if (unlikely(len != sizeof(msg)))
> +			pr_err("%s: kfifo_in anomaly detected\n", __func__);
>  		if (mbox->ops->type == OMAP_MBOX_TYPE1)
>  			break;
>  	}
> @@ -207,11 +200,9 @@ static irqreturn_t mbox_interrupt(int irq, void *p)
>  }
>  
>  static struct omap_mbox_queue *mbox_queue_alloc(struct omap_mbox *mbox,
> -					request_fn_proc *proc,
>  					void (*work) (struct work_struct *),
>  					void (*tasklet)(unsigned long))
>  {
> -	struct request_queue *q;
>  	struct omap_mbox_queue *mq;
>  
>  	mq = kzalloc(sizeof(struct omap_mbox_queue), GFP_KERNEL);
> @@ -220,11 +211,8 @@ static struct omap_mbox_queue *mbox_queue_alloc(struct omap_mbox *mbox,
>  
>  	spin_lock_init(&mq->lock);
>  
> -	q = blk_init_queue(proc, &mq->lock);
> -	if (!q)
> +	if (kfifo_alloc(&mq->fifo, MBOX_KFIFO_SIZE, GFP_KERNEL))
>  		goto error;
> -	q->queuedata = mbox;
> -	mq->queue = q;
>  
>  	if (work)
>  		INIT_WORK(&mq->work, work);
> @@ -239,7 +227,7 @@ error:
>  
>  static void mbox_queue_free(struct omap_mbox_queue *q)
>  {
> -	blk_cleanup_queue(q->queue);
> +	kfifo_free(&q->fifo);
>  	kfree(q);
>  }
>  
> @@ -269,14 +257,14 @@ static int omap_mbox_startup(struct omap_mbox *mbox)
>  		goto fail_request_irq;
>  	}
>  
> -	mq = mbox_queue_alloc(mbox, mbox_txq_fn, NULL, mbox_tx_tasklet);
> +	mq = mbox_queue_alloc(mbox, NULL, mbox_tx_tasklet);
>  	if (!mq) {
>  		ret = -ENOMEM;
>  		goto fail_alloc_txq;
>  	}
>  	mbox->txq = mq;
>  
> -	mq = mbox_queue_alloc(mbox, mbox_rxq_fn, mbox_rx_work, NULL);
> +	mq = mbox_queue_alloc(mbox, mbox_rx_work, NULL);
>  	if (!mq) {
>  		ret = -ENOMEM;
>  		goto fail_alloc_rxq;
> -- 
> 1.6.3.3
> 

Re: [PATCH 4/4] omap: mailbox: convert block api to kfifo

[Ohad Ben-Cohen]

Hi Hiroshi,

On Wed, Apr 28, 2010 at 8:52 AM, Hiroshi DOYU <Hiroshi.DOYU@nokia.com> wrote:
> Hi Ohad,
>
> From: ext Ohad Ben-Cohen <ohad@wizery.com>
> Subject: [PATCH 4/4] omap: mailbox: convert block api to kfifo
> Date: Tue, 27 Apr 2010 19:56:22 +0200
>
>> The underlying buffering implementation of mailbox
>> is converted from block API to kfifo due to the simplicity
>> and speed of kfifo.
>>
>> Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
>> Signed-off-by: Hari Kanigeri <h-kanigeri2@ti.com>
>> ---
>>  arch/arm/plat-omap/include/plat/mailbox.h |    5 +-
>>  arch/arm/plat-omap/mailbox.c              |  108 +++++++++++++----------------
>>  2 files changed, 52 insertions(+), 61 deletions(-)
>>
>> diff --git a/arch/arm/plat-omap/include/plat/mailbox.h b/arch/arm/plat-omap/include/plat/mailbox.h
>> index 729166b..014cc58 100644
>> --- a/arch/arm/plat-omap/include/plat/mailbox.h
>> +++ b/arch/arm/plat-omap/include/plat/mailbox.h
>> @@ -7,6 +7,7 @@
>>  #include <linux/workqueue.h>
>>  #include <linux/blkdev.h>
>>  #include <linux/interrupt.h>
>> +#include <linux/kfifo.h>
>>
>>  typedef u32 mbox_msg_t;
>>  struct omap_mbox;
>> @@ -19,6 +20,8 @@ typedef int __bitwise omap_mbox_type_t;
>>  #define OMAP_MBOX_TYPE1 ((__force omap_mbox_type_t) 1)
>>  #define OMAP_MBOX_TYPE2 ((__force omap_mbox_type_t) 2)
>>
>> +#define MBOX_KFIFO_SIZE      (256)
>
> Can this be a module parameter? Then, OEM could set their optimized value.


Sure.


>
>> +
>>  struct omap_mbox_ops {
>>       omap_mbox_type_t        type;
>>       int             (*startup)(struct omap_mbox *mbox);
>> @@ -42,7 +45,7 @@ struct omap_mbox_ops {
>>
>>  struct omap_mbox_queue {
>>       spinlock_t              lock;
>> -     struct request_queue    *queue;
>> +     struct kfifo            fifo;
>>       struct work_struct      work;
>>       struct tasklet_struct   tasklet;
>>       int     (*callback)(void *);
>> diff --git a/arch/arm/plat-omap/mailbox.c b/arch/arm/plat-omap/mailbox.c
>> index 72b17ad..b1324f3 100644
>> --- a/arch/arm/plat-omap/mailbox.c
>> +++ b/arch/arm/plat-omap/mailbox.c
>> @@ -26,6 +26,7 @@
>>  #include <linux/device.h>
>>  #include <linux/delay.h>
>>  #include <linux/slab.h>
>> +#include <linux/kfifo.h>
>>
>>  #include <plat/mailbox.h>
>>
>> @@ -67,7 +68,7 @@ static inline int is_mbox_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
>>  /*
>>   * message sender
>>   */
>> -static int __mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
>> +static int __mbox_poll_for_space(struct omap_mbox *mbox)
>>  {
>>       int ret = 0, i = 1000;
>>
>> @@ -78,49 +79,54 @@ static int __mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
>>                       return -1;
>>               udelay(1);
>>       }
>> -     mbox_fifo_write(mbox, msg);
>>       return ret;
>>  }
>>
>> -
>>  int omap_mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
>>  {
>> +     struct omap_mbox_queue *mq = mbox->txq;
>> +     int ret = 0, len;
>>
>> -     struct request *rq;
>> -     struct request_queue *q = mbox->txq->queue;
>> +     spin_lock(&mq->lock);
>>
>> -     rq = blk_get_request(q, WRITE, GFP_ATOMIC);
>> -     if (unlikely(!rq))
>> -             return -ENOMEM;
>> +     if (kfifo_avail(&mq->fifo) < sizeof(msg)) {
>> +             ret = -ENOMEM;
>> +             goto out;
>> +     }
>> +
>> +     len = kfifo_in(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
>> +     if (unlikely(len != sizeof(msg))) {
>> +             pr_err("%s: kfifo_in anomaly\n", __func__);
>> +             ret = -ENOMEM;
>> +     }
>>
>> -     blk_insert_request(q, rq, 0, (void *) msg);
>>       tasklet_schedule(&mbox->txq->tasklet);
>>
>> -     return 0;
>> +out:
>> +     spin_unlock(&mq->lock);
>> +     return ret;
>>  }
>>  EXPORT_SYMBOL(omap_mbox_msg_send);
>>
>>  static void mbox_tx_tasklet(unsigned long tx_data)
>>  {
>> -     int ret;
>> -     struct request *rq;
>>       struct omap_mbox *mbox = (struct omap_mbox *)tx_data;
>> -     struct request_queue *q = mbox->txq->queue;
>> -
>> -     while (1) {
>> -
>> -             rq = blk_fetch_request(q);
>> -
>> -             if (!rq)
>> -                     break;
>> +     struct omap_mbox_queue *mq = mbox->txq;
>> +     mbox_msg_t msg;
>> +     int ret;
>>
>> -             ret = __mbox_msg_send(mbox, (mbox_msg_t)rq->special);
>> -             if (ret) {
>> +     while (kfifo_len(&mq->fifo)) {
>> +             if (__mbox_poll_for_space(mbox)) {
>>                       omap_mbox_enable_irq(mbox, IRQ_TX);
>> -                     blk_requeue_request(q, rq);
>> -                     return;
>> +                     break;
>>               }
>> -             blk_end_request_all(rq, 0);
>> +
>> +             ret = kfifo_out(&mq->fifo, (unsigned char *)&msg,
>> +                                                             sizeof(msg));
>> +             if (unlikely(ret != sizeof(msg)))
>> +                     pr_err("%s: kfifo_out anomaly\n", __func__);
>
> No error recovery? same for other anomalies.


I thought about it too, but eventually I think it doesn't really make
a lot of sense:
The only reason that kfifo_out/kfifo_in can fail here is if there's
not enough data/space (respectively).
Since we are checking for the availability of data/space before calling
kfifo_out/kfifo_in, it cannot really fail.
If it does fail, that's a critical bug that we cannot really recover from.
Only reasonable explanation can be a bug in the code (either ours or kfifo's),
and with such a bug it really feels futile to put some recovery.
So maybe we should really make this a WARN_ON.
What do you think ?

Thanks for the review!
Ohad.

>
>> +
>> +             mbox_fifo_write(mbox, msg);
>>       }
>>  }
>>
>> @@ -131,36 +137,22 @@ static void mbox_rx_work(struct work_struct *work)
>>  {
>>       struct omap_mbox_queue *mq =
>>                       container_of(work, struct omap_mbox_queue, work);
>> -     struct omap_mbox *mbox = mq->queue->queuedata;
>> -     struct request_queue *q = mbox->rxq->queue;
>> -     struct request *rq;
>>       mbox_msg_t msg;
>> -     unsigned long flags;
>> +     int len;
>>
>> -     while (1) {
>> -             spin_lock_irqsave(q->queue_lock, flags);
>> -             rq = blk_fetch_request(q);
>> -             spin_unlock_irqrestore(q->queue_lock, flags);
>> -             if (!rq)
>> -                     break;
>> +     while (kfifo_len(&mq->fifo) >= sizeof(msg)) {
>> +             len = kfifo_out(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
>> +             if (unlikely(len != sizeof(msg)))
>> +                     pr_err("%s: kfifo_out anomaly detected\n", __func__);
>>
>> -             msg = (mbox_msg_t)rq->special;
>> -             blk_end_request_all(rq, 0);
>> -             mbox->rxq->callback((void *)msg);
>> +             if (mq->callback)
>> +                     mq->callback((void *)msg);
>>       }
>>  }
>>
>>  /*
>>   * Mailbox interrupt handler
>>   */
>> -static void mbox_txq_fn(struct request_queue *q)
>> -{
>> -}
>> -
>> -static void mbox_rxq_fn(struct request_queue *q)
>> -{
>> -}
>> -
>>  static void __mbox_tx_interrupt(struct omap_mbox *mbox)
>>  {
>>       omap_mbox_disable_irq(mbox, IRQ_TX);
>> @@ -170,19 +162,20 @@ static void __mbox_tx_interrupt(struct omap_mbox *mbox)
>>
>>  static void __mbox_rx_interrupt(struct omap_mbox *mbox)
>>  {
>> -     struct request *rq;
>> +     struct omap_mbox_queue *mq = mbox->rxq;
>>       mbox_msg_t msg;
>> -     struct request_queue *q = mbox->rxq->queue;
>> +     int len;
>>
>>       while (!mbox_fifo_empty(mbox)) {
>> -             rq = blk_get_request(q, WRITE, GFP_ATOMIC);
>> -             if (unlikely(!rq))
>> +             if (unlikely(kfifo_avail(&mq->fifo) < sizeof(msg)))
>>                       goto nomem;
>>
>>               msg = mbox_fifo_read(mbox);
>>
>>
>> -             blk_insert_request(q, rq, 0, (void *)msg);
>> +             len = kfifo_in(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
>> +             if (unlikely(len != sizeof(msg)))
>> +                     pr_err("%s: kfifo_in anomaly detected\n", __func__);
>>               if (mbox->ops->type == OMAP_MBOX_TYPE1)
>>                       break;
>>       }
>> @@ -207,11 +200,9 @@ static irqreturn_t mbox_interrupt(int irq, void *p)
>>  }
>>
>>  static struct omap_mbox_queue *mbox_queue_alloc(struct omap_mbox *mbox,
>> -                                     request_fn_proc *proc,
>>                                       void (*work) (struct work_struct *),
>>                                       void (*tasklet)(unsigned long))
>>  {
>> -     struct request_queue *q;
>>       struct omap_mbox_queue *mq;
>>
>>       mq = kzalloc(sizeof(struct omap_mbox_queue), GFP_KERNEL);
>> @@ -220,11 +211,8 @@ static struct omap_mbox_queue *mbox_queue_alloc(struct omap_mbox *mbox,
>>
>>       spin_lock_init(&mq->lock);
>>
>> -     q = blk_init_queue(proc, &mq->lock);
>> -     if (!q)
>> +     if (kfifo_alloc(&mq->fifo, MBOX_KFIFO_SIZE, GFP_KERNEL))
>>               goto error;
>> -     q->queuedata = mbox;
>> -     mq->queue = q;
>>
>>       if (work)
>>               INIT_WORK(&mq->work, work);
>> @@ -239,7 +227,7 @@ error:
>>
>>  static void mbox_queue_free(struct omap_mbox_queue *q)
>>  {
>> -     blk_cleanup_queue(q->queue);
>> +     kfifo_free(&q->fifo);
>>       kfree(q);
>>  }
>>
>> @@ -269,14 +257,14 @@ static int omap_mbox_startup(struct omap_mbox *mbox)
>>               goto fail_request_irq;
>>       }
>>
>> -     mq = mbox_queue_alloc(mbox, mbox_txq_fn, NULL, mbox_tx_tasklet);
>> +     mq = mbox_queue_alloc(mbox, NULL, mbox_tx_tasklet);
>>       if (!mq) {
>>               ret = -ENOMEM;
>>               goto fail_alloc_txq;
>>       }
>>       mbox->txq = mq;
>>
>> -     mq = mbox_queue_alloc(mbox, mbox_rxq_fn, mbox_rx_work, NULL);
>> +     mq = mbox_queue_alloc(mbox, mbox_rx_work, NULL);
>>       if (!mq) {
>>               ret = -ENOMEM;
>>               goto fail_alloc_rxq;
>> --
>> 1.6.3.3
>>
>
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Re: [PATCH 4/4] omap: mailbox: convert block api to kfifo

[Hiroshi DOYU]

From: ext Ohad Ben-Cohen <ohad@wizery.com>
Subject: Re: [PATCH 4/4] omap: mailbox: convert block api to kfifo
Date: Wed, 28 Apr 2010 13:02:06 +0200

>>> diff --git a/arch/arm/plat-omap/mailbox.c b/arch/arm/plat-omap/mailbox.c
>>> index 72b17ad..b1324f3 100644
>>> --- a/arch/arm/plat-omap/mailbox.c
>>> +++ b/arch/arm/plat-omap/mailbox.c
>>> @@ -26,6 +26,7 @@
>>>  #include <linux/device.h>
>>>  #include <linux/delay.h>
>>>  #include <linux/slab.h>
>>> +#include <linux/kfifo.h>
>>>
>>>  #include <plat/mailbox.h>
>>>
>>> @@ -67,7 +68,7 @@ static inline int is_mbox_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
>>>  /*
>>>   * message sender
>>>   */
>>> -static int __mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
>>> +static int __mbox_poll_for_space(struct omap_mbox *mbox)
>>>  {
>>>       int ret = 0, i = 1000;
>>>
>>> @@ -78,49 +79,54 @@ static int __mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
>>>                       return -1;
>>>               udelay(1);
>>>       }
>>> -     mbox_fifo_write(mbox, msg);
>>>       return ret;
>>>  }
>>>
>>> -
>>>  int omap_mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
>>>  {
>>> +     struct omap_mbox_queue *mq = mbox->txq;
>>> +     int ret = 0, len;
>>>
>>> -     struct request *rq;
>>> -     struct request_queue *q = mbox->txq->queue;
>>> +     spin_lock(&mq->lock);
>>>
>>> -     rq = blk_get_request(q, WRITE, GFP_ATOMIC);
>>> -     if (unlikely(!rq))
>>> -             return -ENOMEM;
>>> +     if (kfifo_avail(&mq->fifo) < sizeof(msg)) {
>>> +             ret = -ENOMEM;
>>> +             goto out;
>>> +     }
>>> +
>>> +     len = kfifo_in(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
>>> +     if (unlikely(len != sizeof(msg))) {
>>> +             pr_err("%s: kfifo_in anomaly\n", __func__);
>>> +             ret = -ENOMEM;
>>> +     }
>>>
>>> -     blk_insert_request(q, rq, 0, (void *) msg);
>>>       tasklet_schedule(&mbox->txq->tasklet);
>>>
>>> -     return 0;
>>> +out:
>>> +     spin_unlock(&mq->lock);
>>> +     return ret;
>>>  }
>>>  EXPORT_SYMBOL(omap_mbox_msg_send);
>>>
>>>  static void mbox_tx_tasklet(unsigned long tx_data)
>>>  {
>>> -     int ret;
>>> -     struct request *rq;
>>>       struct omap_mbox *mbox = (struct omap_mbox *)tx_data;
>>> -     struct request_queue *q = mbox->txq->queue;
>>> -
>>> -     while (1) {
>>> -
>>> -             rq = blk_fetch_request(q);
>>> -
>>> -             if (!rq)
>>> -                     break;
>>> +     struct omap_mbox_queue *mq = mbox->txq;
>>> +     mbox_msg_t msg;
>>> +     int ret;
>>>
>>> -             ret = __mbox_msg_send(mbox, (mbox_msg_t)rq->special);
>>> -             if (ret) {
>>> +     while (kfifo_len(&mq->fifo)) {
>>> +             if (__mbox_poll_for_space(mbox)) {
>>>                       omap_mbox_enable_irq(mbox, IRQ_TX);
>>> -                     blk_requeue_request(q, rq);
>>> -                     return;
>>> +                     break;
>>>               }
>>> -             blk_end_request_all(rq, 0);
>>> +
>>> +             ret = kfifo_out(&mq->fifo, (unsigned char *)&msg,
>>> +                                                             sizeof(msg));
>>> +             if (unlikely(ret != sizeof(msg)))
>>> +                     pr_err("%s: kfifo_out anomaly\n", __func__);
>>
>> No error recovery? same for other anomalies.
> 
> I thought about it too, but eventually I think it doesn't really make
> a lot of sense:
> The only reason that kfifo_out/kfifo_in can fail here is if there's
> not enough data/space (respectively).
> Since we are checking for the availability of data/space before calling
> kfifo_out/kfifo_in, it cannot really fail.
> If it does fail, that's a critical bug that we cannot really recover from.
> Only reasonable explanation can be a bug in the code (either ours or kfifo's),
> and with such a bug it really feels futile to put some recovery.
> So maybe we should really make this a WARN_ON.
> What do you think ?

Makes sense. What about BUG_ON if it shouldn't happen theoretically?
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Re: [PATCH 4/4] omap: mailbox: convert block api to kfifo

[Ohad Ben-Cohen]

On Wed, Apr 28, 2010 at 2:16 PM, Hiroshi DOYU <Hiroshi.DOYU@nokia.com> wrote:
> From: ext Ohad Ben-Cohen <ohad@wizery.com>
> Subject: Re: [PATCH 4/4] omap: mailbox: convert block api to kfifo
> Date: Wed, 28 Apr 2010 13:02:06 +0200
>
>>>> diff --git a/arch/arm/plat-omap/mailbox.c b/arch/arm/plat-omap/mailbox.c
>>>> index 72b17ad..b1324f3 100644
>>>> --- a/arch/arm/plat-omap/mailbox.c
>>>> +++ b/arch/arm/plat-omap/mailbox.c
>>>> @@ -26,6 +26,7 @@
>>>>  #include <linux/device.h>
>>>>  #include <linux/delay.h>
>>>>  #include <linux/slab.h>
>>>> +#include <linux/kfifo.h>
>>>>
>>>>  #include <plat/mailbox.h>
>>>>
>>>> @@ -67,7 +68,7 @@ static inline int is_mbox_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
>>>>  /*
>>>>   * message sender
>>>>   */
>>>> -static int __mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
>>>> +static int __mbox_poll_for_space(struct omap_mbox *mbox)
>>>>  {
>>>>       int ret = 0, i = 1000;
>>>>
>>>> @@ -78,49 +79,54 @@ static int __mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
>>>>                       return -1;
>>>>               udelay(1);
>>>>       }
>>>> -     mbox_fifo_write(mbox, msg);
>>>>       return ret;
>>>>  }
>>>>
>>>> -
>>>>  int omap_mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
>>>>  {
>>>> +     struct omap_mbox_queue *mq = mbox->txq;
>>>> +     int ret = 0, len;
>>>>
>>>> -     struct request *rq;
>>>> -     struct request_queue *q = mbox->txq->queue;
>>>> +     spin_lock(&mq->lock);
>>>>
>>>> -     rq = blk_get_request(q, WRITE, GFP_ATOMIC);
>>>> -     if (unlikely(!rq))
>>>> -             return -ENOMEM;
>>>> +     if (kfifo_avail(&mq->fifo) < sizeof(msg)) {
>>>> +             ret = -ENOMEM;
>>>> +             goto out;
>>>> +     }
>>>> +
>>>> +     len = kfifo_in(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
>>>> +     if (unlikely(len != sizeof(msg))) {
>>>> +             pr_err("%s: kfifo_in anomaly\n", __func__);
>>>> +             ret = -ENOMEM;
>>>> +     }
>>>>
>>>> -     blk_insert_request(q, rq, 0, (void *) msg);
>>>>       tasklet_schedule(&mbox->txq->tasklet);
>>>>
>>>> -     return 0;
>>>> +out:
>>>> +     spin_unlock(&mq->lock);
>>>> +     return ret;
>>>>  }
>>>>  EXPORT_SYMBOL(omap_mbox_msg_send);
>>>>
>>>>  static void mbox_tx_tasklet(unsigned long tx_data)
>>>>  {
>>>> -     int ret;
>>>> -     struct request *rq;
>>>>       struct omap_mbox *mbox = (struct omap_mbox *)tx_data;
>>>> -     struct request_queue *q = mbox->txq->queue;
>>>> -
>>>> -     while (1) {
>>>> -
>>>> -             rq = blk_fetch_request(q);
>>>> -
>>>> -             if (!rq)
>>>> -                     break;
>>>> +     struct omap_mbox_queue *mq = mbox->txq;
>>>> +     mbox_msg_t msg;
>>>> +     int ret;
>>>>
>>>> -             ret = __mbox_msg_send(mbox, (mbox_msg_t)rq->special);
>>>> -             if (ret) {
>>>> +     while (kfifo_len(&mq->fifo)) {
>>>> +             if (__mbox_poll_for_space(mbox)) {
>>>>                       omap_mbox_enable_irq(mbox, IRQ_TX);
>>>> -                     blk_requeue_request(q, rq);
>>>> -                     return;
>>>> +                     break;
>>>>               }
>>>> -             blk_end_request_all(rq, 0);
>>>> +
>>>> +             ret = kfifo_out(&mq->fifo, (unsigned char *)&msg,
>>>> +                                                             sizeof(msg));
>>>> +             if (unlikely(ret != sizeof(msg)))
>>>> +                     pr_err("%s: kfifo_out anomaly\n", __func__);
>>>
>>> No error recovery? same for other anomalies.
>>
>> I thought about it too, but eventually I think it doesn't really make
>> a lot of sense:
>> The only reason that kfifo_out/kfifo_in can fail here is if there's
>> not enough data/space (respectively).
>> Since we are checking for the availability of data/space before calling
>> kfifo_out/kfifo_in, it cannot really fail.
>> If it does fail, that's a critical bug that we cannot really recover from.
>> Only reasonable explanation can be a bug in the code (either ours or kfifo's),
>> and with such a bug it really feels futile to put some recovery.
>> So maybe we should really make this a WARN_ON.
>> What do you think ?
>
> Makes sense. What about BUG_ON if it shouldn't happen theoretically?

I'm not sure this bug is critical enough to panic and enforce the user
to reboot immediately - he can probably still do a clean shutdown here.

Thanks,
Ohad.

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Re: [PATCH 4/4] omap: mailbox: convert block api to kfifo

[Hiroshi DOYU]

From: ext Ohad Ben-Cohen <ohad@wizery.com>
Subject: Re: [PATCH 4/4] omap: mailbox: convert block api to kfifo
Date: Wed, 28 Apr 2010 13:25:41 +0200

> On Wed, Apr 28, 2010 at 2:16 PM, Hiroshi DOYU <Hiroshi.DOYU@nokia.com> wrote:
>> From: ext Ohad Ben-Cohen <ohad@wizery.com>
>> Subject: Re: [PATCH 4/4] omap: mailbox: convert block api to kfifo
>> Date: Wed, 28 Apr 2010 13:02:06 +0200
>>
>>>>> diff --git a/arch/arm/plat-omap/mailbox.c b/arch/arm/plat-omap/mailbox.c
>>>>> index 72b17ad..b1324f3 100644
>>>>> --- a/arch/arm/plat-omap/mailbox.c
>>>>> +++ b/arch/arm/plat-omap/mailbox.c
>>>>> @@ -26,6 +26,7 @@
>>>>>  #include <linux/device.h>
>>>>>  #include <linux/delay.h>
>>>>>  #include <linux/slab.h>
>>>>> +#include <linux/kfifo.h>
>>>>>
>>>>>  #include <plat/mailbox.h>
>>>>>
>>>>> @@ -67,7 +68,7 @@ static inline int is_mbox_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
>>>>>  /*
>>>>>   * message sender
>>>>>   */
>>>>> -static int __mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
>>>>> +static int __mbox_poll_for_space(struct omap_mbox *mbox)
>>>>>  {
>>>>>       int ret = 0, i = 1000;
>>>>>
>>>>> @@ -78,49 +79,54 @@ static int __mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
>>>>>                       return -1;
>>>>>               udelay(1);
>>>>>       }
>>>>> -     mbox_fifo_write(mbox, msg);
>>>>>       return ret;
>>>>>  }
>>>>>
>>>>> -
>>>>>  int omap_mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
>>>>>  {
>>>>> +     struct omap_mbox_queue *mq = mbox->txq;
>>>>> +     int ret = 0, len;
>>>>>
>>>>> -     struct request *rq;
>>>>> -     struct request_queue *q = mbox->txq->queue;
>>>>> +     spin_lock(&mq->lock);
>>>>>
>>>>> -     rq = blk_get_request(q, WRITE, GFP_ATOMIC);
>>>>> -     if (unlikely(!rq))
>>>>> -             return -ENOMEM;
>>>>> +     if (kfifo_avail(&mq->fifo) < sizeof(msg)) {
>>>>> +             ret = -ENOMEM;
>>>>> +             goto out;
>>>>> +     }
>>>>> +
>>>>> +     len = kfifo_in(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
>>>>> +     if (unlikely(len != sizeof(msg))) {
>>>>> +             pr_err("%s: kfifo_in anomaly\n", __func__);
>>>>> +             ret = -ENOMEM;
>>>>> +     }
>>>>>
>>>>> -     blk_insert_request(q, rq, 0, (void *) msg);
>>>>>       tasklet_schedule(&mbox->txq->tasklet);
>>>>>
>>>>> -     return 0;
>>>>> +out:
>>>>> +     spin_unlock(&mq->lock);
>>>>> +     return ret;
>>>>>  }
>>>>>  EXPORT_SYMBOL(omap_mbox_msg_send);
>>>>>
>>>>>  static void mbox_tx_tasklet(unsigned long tx_data)
>>>>>  {
>>>>> -     int ret;
>>>>> -     struct request *rq;
>>>>>       struct omap_mbox *mbox = (struct omap_mbox *)tx_data;
>>>>> -     struct request_queue *q = mbox->txq->queue;
>>>>> -
>>>>> -     while (1) {
>>>>> -
>>>>> -             rq = blk_fetch_request(q);
>>>>> -
>>>>> -             if (!rq)
>>>>> -                     break;
>>>>> +     struct omap_mbox_queue *mq = mbox->txq;
>>>>> +     mbox_msg_t msg;
>>>>> +     int ret;
>>>>>
>>>>> -             ret = __mbox_msg_send(mbox, (mbox_msg_t)rq->special);
>>>>> -             if (ret) {
>>>>> +     while (kfifo_len(&mq->fifo)) {
>>>>> +             if (__mbox_poll_for_space(mbox)) {
>>>>>                       omap_mbox_enable_irq(mbox, IRQ_TX);
>>>>> -                     blk_requeue_request(q, rq);
>>>>> -                     return;
>>>>> +                     break;
>>>>>               }
>>>>> -             blk_end_request_all(rq, 0);
>>>>> +
>>>>> +             ret = kfifo_out(&mq->fifo, (unsigned char *)&msg,
>>>>> +                                                             sizeof(msg));
>>>>> +             if (unlikely(ret != sizeof(msg)))
>>>>> +                     pr_err("%s: kfifo_out anomaly\n", __func__);
>>>>
>>>> No error recovery? same for other anomalies.
>>>
>>> I thought about it too, but eventually I think it doesn't really make
>>> a lot of sense:
>>> The only reason that kfifo_out/kfifo_in can fail here is if there's
>>> not enough data/space (respectively).
>>> Since we are checking for the availability of data/space before calling
>>> kfifo_out/kfifo_in, it cannot really fail.
>>> If it does fail, that's a critical bug that we cannot really recover from.
>>> Only reasonable explanation can be a bug in the code (either ours or kfifo's),
>>> and with such a bug it really feels futile to put some recovery.
>>> So maybe we should really make this a WARN_ON.
>>> What do you think ?
>>
>> Makes sense. What about BUG_ON if it shouldn't happen theoretically?
> 
> I'm not sure this bug is critical enough to panic and enforce the user
> to reboot immediately - he can probably still do a clean shutdown here.

I agree that WARN_ON would be enough for this case. I just thought of
the rareness of this triggering.
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Re: [PATCH 4/4] omap: mailbox: convert block api to kfifo

[Ohad Ben-Cohen]

On Wed, Apr 28, 2010 at 2:52 PM, Hiroshi DOYU <Hiroshi.DOYU@nokia.com> wrote:
> From: ext Ohad Ben-Cohen <ohad@wizery.com>
> Subject: Re: [PATCH 4/4] omap: mailbox: convert block api to kfifo
> Date: Wed, 28 Apr 2010 13:25:41 +0200
>
>> On Wed, Apr 28, 2010 at 2:16 PM, Hiroshi DOYU <Hiroshi.DOYU@nokia.com> wrote:
>>> From: ext Ohad Ben-Cohen <ohad@wizery.com>
>>> Subject: Re: [PATCH 4/4] omap: mailbox: convert block api to kfifo
>>> Date: Wed, 28 Apr 2010 13:02:06 +0200
>>>
>>>>>> diff --git a/arch/arm/plat-omap/mailbox.c b/arch/arm/plat-omap/mailbox.c
>>>>>> index 72b17ad..b1324f3 100644
>>>>>> --- a/arch/arm/plat-omap/mailbox.c
>>>>>> +++ b/arch/arm/plat-omap/mailbox.c
>>>>>> @@ -26,6 +26,7 @@
>>>>>>  #include <linux/device.h>
>>>>>>  #include <linux/delay.h>
>>>>>>  #include <linux/slab.h>
>>>>>> +#include <linux/kfifo.h>
>>>>>>
>>>>>>  #include <plat/mailbox.h>
>>>>>>
>>>>>> @@ -67,7 +68,7 @@ static inline int is_mbox_irq(struct omap_mbox *mbox, omap_mbox_irq_t irq)
>>>>>>  /*
>>>>>>   * message sender
>>>>>>   */
>>>>>> -static int __mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
>>>>>> +static int __mbox_poll_for_space(struct omap_mbox *mbox)
>>>>>>  {
>>>>>>       int ret = 0, i = 1000;
>>>>>>
>>>>>> @@ -78,49 +79,54 @@ static int __mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
>>>>>>                       return -1;
>>>>>>               udelay(1);
>>>>>>       }
>>>>>> -     mbox_fifo_write(mbox, msg);
>>>>>>       return ret;
>>>>>>  }
>>>>>>
>>>>>> -
>>>>>>  int omap_mbox_msg_send(struct omap_mbox *mbox, mbox_msg_t msg)
>>>>>>  {
>>>>>> +     struct omap_mbox_queue *mq = mbox->txq;
>>>>>> +     int ret = 0, len;
>>>>>>
>>>>>> -     struct request *rq;
>>>>>> -     struct request_queue *q = mbox->txq->queue;
>>>>>> +     spin_lock(&mq->lock);
>>>>>>
>>>>>> -     rq = blk_get_request(q, WRITE, GFP_ATOMIC);
>>>>>> -     if (unlikely(!rq))
>>>>>> -             return -ENOMEM;
>>>>>> +     if (kfifo_avail(&mq->fifo) < sizeof(msg)) {
>>>>>> +             ret = -ENOMEM;
>>>>>> +             goto out;
>>>>>> +     }
>>>>>> +
>>>>>> +     len = kfifo_in(&mq->fifo, (unsigned char *)&msg, sizeof(msg));
>>>>>> +     if (unlikely(len != sizeof(msg))) {
>>>>>> +             pr_err("%s: kfifo_in anomaly\n", __func__);
>>>>>> +             ret = -ENOMEM;
>>>>>> +     }
>>>>>>
>>>>>> -     blk_insert_request(q, rq, 0, (void *) msg);
>>>>>>       tasklet_schedule(&mbox->txq->tasklet);
>>>>>>
>>>>>> -     return 0;
>>>>>> +out:
>>>>>> +     spin_unlock(&mq->lock);
>>>>>> +     return ret;
>>>>>>  }
>>>>>>  EXPORT_SYMBOL(omap_mbox_msg_send);
>>>>>>
>>>>>>  static void mbox_tx_tasklet(unsigned long tx_data)
>>>>>>  {
>>>>>> -     int ret;
>>>>>> -     struct request *rq;
>>>>>>       struct omap_mbox *mbox = (struct omap_mbox *)tx_data;
>>>>>> -     struct request_queue *q = mbox->txq->queue;
>>>>>> -
>>>>>> -     while (1) {
>>>>>> -
>>>>>> -             rq = blk_fetch_request(q);
>>>>>> -
>>>>>> -             if (!rq)
>>>>>> -                     break;
>>>>>> +     struct omap_mbox_queue *mq = mbox->txq;
>>>>>> +     mbox_msg_t msg;
>>>>>> +     int ret;
>>>>>>
>>>>>> -             ret = __mbox_msg_send(mbox, (mbox_msg_t)rq->special);
>>>>>> -             if (ret) {
>>>>>> +     while (kfifo_len(&mq->fifo)) {
>>>>>> +             if (__mbox_poll_for_space(mbox)) {
>>>>>>                       omap_mbox_enable_irq(mbox, IRQ_TX);
>>>>>> -                     blk_requeue_request(q, rq);
>>>>>> -                     return;
>>>>>> +                     break;
>>>>>>               }
>>>>>> -             blk_end_request_all(rq, 0);
>>>>>> +
>>>>>> +             ret = kfifo_out(&mq->fifo, (unsigned char *)&msg,
>>>>>> +                                                             sizeof(msg));
>>>>>> +             if (unlikely(ret != sizeof(msg)))
>>>>>> +                     pr_err("%s: kfifo_out anomaly\n", __func__);
>>>>>
>>>>> No error recovery? same for other anomalies.
>>>>
>>>> I thought about it too, but eventually I think it doesn't really make
>>>> a lot of sense:
>>>> The only reason that kfifo_out/kfifo_in can fail here is if there's
>>>> not enough data/space (respectively).
>>>> Since we are checking for the availability of data/space before calling
>>>> kfifo_out/kfifo_in, it cannot really fail.
>>>> If it does fail, that's a critical bug that we cannot really recover from.
>>>> Only reasonable explanation can be a bug in the code (either ours or kfifo's),
>>>> and with such a bug it really feels futile to put some recovery.
>>>> So maybe we should really make this a WARN_ON.
>>>> What do you think ?
>>>
>>> Makes sense. What about BUG_ON if it shouldn't happen theoretically?
>>
>> I'm not sure this bug is critical enough to panic and enforce the user
>> to reboot immediately - he can probably still do a clean shutdown here.
>
> I agree that WARN_ON would be enough for this case. I just thought of
> the rareness of this triggering.

Yeah, I was thinking exactly the same, and wanted to put BUG_ON too initially,
but the combination of its calling panic and its header comment
convinced me otherwise:

/*
 * Don't use BUG() or BUG_ON() unless there's really no way out; one
 * example might be detecting data structure corruption in the middle
 * of an operation that can't be backed out of.  If the (sub)system
 * can somehow continue operating, perhaps with reduced functionality,
 * it's probably not BUG-worthy.
 *
 * If you're tempted to BUG(), think again:  is completely giving up
 * really the *only* solution?  There are usually better options, where
 * users don't need to reboot ASAP and can mostly shut down cleanly.
 */




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Re: [PATCH 4/4] omap: mailbox: convert block api to kfifo

[Hiroshi DOYU]

From: ext Ohad Ben-Cohen <ohad@wizery.com>
Subject: [PATCH 4/4] omap: mailbox: convert block api to kfifo
Date: Tue, 27 Apr 2010 19:56:22 +0200

> The underlying buffering implementation of mailbox
> is converted from block API to kfifo due to the simplicity
> and speed of kfifo.
> 
> Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
> Signed-off-by: Hari Kanigeri <h-kanigeri2@ti.com>
> ---
>  arch/arm/plat-omap/include/plat/mailbox.h |    5 +-
>  arch/arm/plat-omap/mailbox.c              |  108 +++++++++++++----------------
>  2 files changed, 52 insertions(+), 61 deletions(-)
> 
> diff --git a/arch/arm/plat-omap/include/plat/mailbox.h b/arch/arm/plat-omap/include/plat/mailbox.h
> index 729166b..014cc58 100644
> --- a/arch/arm/plat-omap/include/plat/mailbox.h
> +++ b/arch/arm/plat-omap/include/plat/mailbox.h
> @@ -7,6 +7,7 @@
>  #include <linux/workqueue.h>
>  #include <linux/blkdev.h>

Also the above is not necessary?

>  #include <linux/interrupt.h>
> +#include <linux/kfifo.h>

Re: [PATCH 4/4] omap: mailbox: convert block api to kfifo

[Ohad Ben-Cohen]

On Wed, Apr 28, 2010 at 8:56 AM, Hiroshi DOYU <Hiroshi.DOYU@nokia.com> wrote:
> From: ext Ohad Ben-Cohen <ohad@wizery.com>
> Subject: [PATCH 4/4] omap: mailbox: convert block api to kfifo
> Date: Tue, 27 Apr 2010 19:56:22 +0200
>
>> The underlying buffering implementation of mailbox
>> is converted from block API to kfifo due to the simplicity
>> and speed of kfifo.
>>
>> Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>
>> Signed-off-by: Hari Kanigeri <h-kanigeri2@ti.com>
>> ---
>>  arch/arm/plat-omap/include/plat/mailbox.h |    5 +-
>>  arch/arm/plat-omap/mailbox.c              |  108 +++++++++++++----------------
>>  2 files changed, 52 insertions(+), 61 deletions(-)
>>
>> diff --git a/arch/arm/plat-omap/include/plat/mailbox.h b/arch/arm/plat-omap/include/plat/mailbox.h
>> index 729166b..014cc58 100644
>> --- a/arch/arm/plat-omap/include/plat/mailbox.h
>> +++ b/arch/arm/plat-omap/include/plat/mailbox.h
>> @@ -7,6 +7,7 @@
>>  #include <linux/workqueue.h>
>>  #include <linux/blkdev.h>
>
> Also the above is not necessary?

Good point. It will be removed.

Thanks,
Ohad.

>
>>  #include <linux/interrupt.h>
>> +#include <linux/kfifo.h>
>
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