diff mbox series

[2/5] dmaengine: virt-dma: Do not call desc_free() under a spin_lock

Message ID 20191206135344.29330-3-s.hauer@pengutronix.de (mailing list archive)
State Changes Requested
Headers show
Series virt-dma and i.MX SDMA fixes | expand

Commit Message

Sascha Hauer Dec. 6, 2019, 1:53 p.m. UTC 
vchan_vdesc_fini() shouldn't be called under a spin_lock. This is done
in two places, once in vchan_terminate_vdesc() and once in
vchan_synchronize(). Instead of freeing the vdesc right away, collect
the aborted vdescs on a separate list and free them along with the other
vdescs.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 drivers/dma/virt-dma.c |  1 +
 drivers/dma/virt-dma.h | 17 +++--------------
 2 files changed, 4 insertions(+), 14 deletions(-)

Comments

Peter Ujfalusi Dec. 9, 2019, 7:48 a.m. UTC | #1 
Hi Sascha,


On 06/12/2019 15.53, Sascha Hauer wrote:
> vchan_vdesc_fini() shouldn't be called under a spin_lock. This is done
> in two places, once in vchan_terminate_vdesc() and once in
> vchan_synchronize(). Instead of freeing the vdesc right away, collect
> the aborted vdescs on a separate list and free them along with the other
> vdescs.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> ---
>  drivers/dma/virt-dma.c |  1 +
>  drivers/dma/virt-dma.h | 17 +++--------------
>  2 files changed, 4 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/dma/virt-dma.c b/drivers/dma/virt-dma.c
> index ec4adf4260a0..87d5bd53c98b 100644
> --- a/drivers/dma/virt-dma.c
> +++ b/drivers/dma/virt-dma.c
> @@ -135,6 +135,7 @@ void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev)
>  	INIT_LIST_HEAD(&vc->desc_submitted);
>  	INIT_LIST_HEAD(&vc->desc_issued);
>  	INIT_LIST_HEAD(&vc->desc_completed);
> +	INIT_LIST_HEAD(&vc->desc_aborted);

Can we keep the terminated term instead of aborted: desc_terminated

>  
>  	tasklet_init(&vc->task, vchan_complete, (unsigned long)vc);
>  
> diff --git a/drivers/dma/virt-dma.h b/drivers/dma/virt-dma.h
> index 41883ee2c29f..6cae93624f0d 100644
> --- a/drivers/dma/virt-dma.h
> +++ b/drivers/dma/virt-dma.h
> @@ -31,9 +31,9 @@ struct virt_dma_chan {
>  	struct list_head desc_submitted;
>  	struct list_head desc_issued;
>  	struct list_head desc_completed;
> +	struct list_head desc_aborted;
>  
>  	struct virt_dma_desc *cyclic;
> -	struct virt_dma_desc *vd_terminated;
>  };
>  
>  static inline struct virt_dma_chan *to_virt_chan(struct dma_chan *chan)
> @@ -146,11 +146,8 @@ static inline void vchan_terminate_vdesc(struct virt_dma_desc *vd)
>  {
>  	struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
>  
> -	/* free up stuck descriptor */
> -	if (vc->vd_terminated)
> -		vchan_vdesc_fini(vc->vd_terminated);
> +	list_add_tail(&vd->node, &vc->desc_aborted);
>  
> -	vc->vd_terminated = vd;
>  	if (vc->cyclic == vd)
>  		vc->cyclic = NULL;
>  }
> @@ -184,6 +181,7 @@ static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
>  	list_splice_tail_init(&vc->desc_submitted, head);
>  	list_splice_tail_init(&vc->desc_issued, head);
>  	list_splice_tail_init(&vc->desc_completed, head);
> +	list_splice_tail_init(&vc->desc_aborted, head);
>  }
>  
>  static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
> @@ -212,16 +210,7 @@ static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
>   */
>  static inline void vchan_synchronize(struct virt_dma_chan *vc)
>  {
> -	unsigned long flags;
> -
>  	tasklet_kill(&vc->task);
> -
> -	spin_lock_irqsave(&vc->lock, flags);
> -	if (vc->vd_terminated) {
> -		vchan_vdesc_fini(vc->vd_terminated);
> -		vc->vd_terminated = NULL;
> -	}
> -	spin_unlock_irqrestore(&vc->lock, flags);

We don't want the terminated descriptors to accumulate until the channel
is freed up.

spin_lock_irqsave(&vc->lock, flags);
list_splice_tail_init(&vc->desc_terminated, &head);
spin_unlock_irqrestore(&vc->lock, flags);

list_for_each_entry_safe(vd, _vd, &head, node) {
	list_del(&vd->node);
	vchan_vdesc_fini(vd);
}


>  }
>  
>  #endif
> 

- Péter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
Peter Ujfalusi Dec. 9, 2019, 8:33 a.m. UTC | #2 
On 09/12/2019 9.48, Peter Ujfalusi wrote:
> Hi Sascha,
> 
> 
> On 06/12/2019 15.53, Sascha Hauer wrote:
>> vchan_vdesc_fini() shouldn't be called under a spin_lock. This is done
>> in two places, once in vchan_terminate_vdesc() and once in
>> vchan_synchronize(). Instead of freeing the vdesc right away, collect
>> the aborted vdescs on a separate list and free them along with the other
>> vdescs.
>>
>> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
>> ---
>>  drivers/dma/virt-dma.c |  1 +
>>  drivers/dma/virt-dma.h | 17 +++--------------
>>  2 files changed, 4 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/dma/virt-dma.c b/drivers/dma/virt-dma.c
>> index ec4adf4260a0..87d5bd53c98b 100644
>> --- a/drivers/dma/virt-dma.c
>> +++ b/drivers/dma/virt-dma.c
>> @@ -135,6 +135,7 @@ void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev)
>>  	INIT_LIST_HEAD(&vc->desc_submitted);
>>  	INIT_LIST_HEAD(&vc->desc_issued);
>>  	INIT_LIST_HEAD(&vc->desc_completed);
>> +	INIT_LIST_HEAD(&vc->desc_aborted);
> 
> Can we keep the terminated term instead of aborted: desc_terminated
> 
>>  
>>  	tasklet_init(&vc->task, vchan_complete, (unsigned long)vc);
>>  
>> diff --git a/drivers/dma/virt-dma.h b/drivers/dma/virt-dma.h
>> index 41883ee2c29f..6cae93624f0d 100644
>> --- a/drivers/dma/virt-dma.h
>> +++ b/drivers/dma/virt-dma.h
>> @@ -31,9 +31,9 @@ struct virt_dma_chan {
>>  	struct list_head desc_submitted;
>>  	struct list_head desc_issued;
>>  	struct list_head desc_completed;
>> +	struct list_head desc_aborted;
>>  
>>  	struct virt_dma_desc *cyclic;
>> -	struct virt_dma_desc *vd_terminated;
>>  };
>>  
>>  static inline struct virt_dma_chan *to_virt_chan(struct dma_chan *chan)
>> @@ -146,11 +146,8 @@ static inline void vchan_terminate_vdesc(struct virt_dma_desc *vd)
>>  {
>>  	struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
>>  
>> -	/* free up stuck descriptor */
>> -	if (vc->vd_terminated)
>> -		vchan_vdesc_fini(vc->vd_terminated);
>> +	list_add_tail(&vd->node, &vc->desc_aborted);
>>  
>> -	vc->vd_terminated = vd;
>>  	if (vc->cyclic == vd)
>>  		vc->cyclic = NULL;
>>  }
>> @@ -184,6 +181,7 @@ static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
>>  	list_splice_tail_init(&vc->desc_submitted, head);
>>  	list_splice_tail_init(&vc->desc_issued, head);
>>  	list_splice_tail_init(&vc->desc_completed, head);
>> +	list_splice_tail_init(&vc->desc_aborted, head);
>>  }
>>  
>>  static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
>> @@ -212,16 +210,7 @@ static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
>>   */
>>  static inline void vchan_synchronize(struct virt_dma_chan *vc)
>>  {
>> -	unsigned long flags;
>> -
>>  	tasklet_kill(&vc->task);
>> -
>> -	spin_lock_irqsave(&vc->lock, flags);
>> -	if (vc->vd_terminated) {
>> -		vchan_vdesc_fini(vc->vd_terminated);
>> -		vc->vd_terminated = NULL;
>> -	}
>> -	spin_unlock_irqrestore(&vc->lock, flags);
> 
> We don't want the terminated descriptors to accumulate until the channel
> is freed up.

Well, most DMA driver will clean it up in their terminate_all, but it is
better to do it in synchronize as well.

> 
> spin_lock_irqsave(&vc->lock, flags);
> list_splice_tail_init(&vc->desc_terminated, &head);
> spin_unlock_irqrestore(&vc->lock, flags);
> 
> list_for_each_entry_safe(vd, _vd, &head, node) {
> 	list_del(&vd->node);
> 	vchan_vdesc_fini(vd);
> }
> 
> 
>>  }
>>  
>>  #endif
>>
> 
> - Péter
> 
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
> 

- Péter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
Sascha Hauer Dec. 10, 2019, 11:58 a.m. UTC | #3 
On Mon, Dec 09, 2019 at 09:48:22AM +0200, Peter Ujfalusi wrote:
> Hi Sascha,
> 
> 
> On 06/12/2019 15.53, Sascha Hauer wrote:
> > vchan_vdesc_fini() shouldn't be called under a spin_lock. This is done
> > in two places, once in vchan_terminate_vdesc() and once in
> > vchan_synchronize(). Instead of freeing the vdesc right away, collect
> > the aborted vdescs on a separate list and free them along with the other
> > vdescs.
> > 
> > Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> > ---
> >  drivers/dma/virt-dma.c |  1 +
> >  drivers/dma/virt-dma.h | 17 +++--------------
> >  2 files changed, 4 insertions(+), 14 deletions(-)
> > 
> > diff --git a/drivers/dma/virt-dma.c b/drivers/dma/virt-dma.c
> > index ec4adf4260a0..87d5bd53c98b 100644
> > --- a/drivers/dma/virt-dma.c
> > +++ b/drivers/dma/virt-dma.c
> > @@ -135,6 +135,7 @@ void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev)
> >  	INIT_LIST_HEAD(&vc->desc_submitted);
> >  	INIT_LIST_HEAD(&vc->desc_issued);
> >  	INIT_LIST_HEAD(&vc->desc_completed);
> > +	INIT_LIST_HEAD(&vc->desc_aborted);
> 
> Can we keep the terminated term instead of aborted: desc_terminated

Sure.

> >  	tasklet_kill(&vc->task);
> > -
> > -	spin_lock_irqsave(&vc->lock, flags);
> > -	if (vc->vd_terminated) {
> > -		vchan_vdesc_fini(vc->vd_terminated);
> > -		vc->vd_terminated = NULL;
> > -	}
> > -	spin_unlock_irqrestore(&vc->lock, flags);
> 
> We don't want the terminated descriptors to accumulate until the channel
> is freed up.

Nothing easier than that. I just have to revert to an earlier version
before I decided that it's better to free up the descriptors at the end ;)

I'll send a v2 shortly.

Sascha
diff mbox series

Patch

diff --git a/drivers/dma/virt-dma.c b/drivers/dma/virt-dma.c
index ec4adf4260a0..87d5bd53c98b 100644
--- a/drivers/dma/virt-dma.c
+++ b/drivers/dma/virt-dma.c
@@ -135,6 +135,7 @@  void vchan_init(struct virt_dma_chan *vc, struct dma_device *dmadev)
 	INIT_LIST_HEAD(&vc->desc_submitted);
 	INIT_LIST_HEAD(&vc->desc_issued);
 	INIT_LIST_HEAD(&vc->desc_completed);
+	INIT_LIST_HEAD(&vc->desc_aborted);
 
 	tasklet_init(&vc->task, vchan_complete, (unsigned long)vc);
 
diff --git a/drivers/dma/virt-dma.h b/drivers/dma/virt-dma.h
index 41883ee2c29f..6cae93624f0d 100644
--- a/drivers/dma/virt-dma.h
+++ b/drivers/dma/virt-dma.h
@@ -31,9 +31,9 @@  struct virt_dma_chan {
 	struct list_head desc_submitted;
 	struct list_head desc_issued;
 	struct list_head desc_completed;
+	struct list_head desc_aborted;
 
 	struct virt_dma_desc *cyclic;
-	struct virt_dma_desc *vd_terminated;
 };
 
 static inline struct virt_dma_chan *to_virt_chan(struct dma_chan *chan)
@@ -146,11 +146,8 @@  static inline void vchan_terminate_vdesc(struct virt_dma_desc *vd)
 {
 	struct virt_dma_chan *vc = to_virt_chan(vd->tx.chan);
 
-	/* free up stuck descriptor */
-	if (vc->vd_terminated)
-		vchan_vdesc_fini(vc->vd_terminated);
+	list_add_tail(&vd->node, &vc->desc_aborted);
 
-	vc->vd_terminated = vd;
 	if (vc->cyclic == vd)
 		vc->cyclic = NULL;
 }
@@ -184,6 +181,7 @@  static inline void vchan_get_all_descriptors(struct virt_dma_chan *vc,
 	list_splice_tail_init(&vc->desc_submitted, head);
 	list_splice_tail_init(&vc->desc_issued, head);
 	list_splice_tail_init(&vc->desc_completed, head);
+	list_splice_tail_init(&vc->desc_aborted, head);
 }
 
 static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
@@ -212,16 +210,7 @@  static inline void vchan_free_chan_resources(struct virt_dma_chan *vc)
  */
 static inline void vchan_synchronize(struct virt_dma_chan *vc)
 {
-	unsigned long flags;
-
 	tasklet_kill(&vc->task);
-
-	spin_lock_irqsave(&vc->lock, flags);
-	if (vc->vd_terminated) {
-		vchan_vdesc_fini(vc->vd_terminated);
-		vc->vd_terminated = NULL;
-	}
-	spin_unlock_irqrestore(&vc->lock, flags);
 }
 
 #endif