[PATCH] dmaengine: sirf: fix kernel panic under one race condition

[PATCH] dmaengine: sirf: fix kernel panic under one race condition

[Barry Song]

From: Yanchang Li <yl22@csr.com>

If DMA interrupt comes and is latched by IRQ controller during the
execution of dma_terminate_all(), dma_irq routine will be executed
after dma terminated, and it will cause kernel panic.
We clear DMA interrupts in dma_terminate_all() to avoid this useless
interrupt.

Signed-off-by: Yanchang Li <yl22@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
---
 drivers/dma/sirf-dma.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/dma/sirf-dma.c b/drivers/dma/sirf-dma.c
index 8c5186c..7d5598d 100644
--- a/drivers/dma/sirf-dma.c
+++ b/drivers/dma/sirf-dma.c
@@ -455,6 +455,7 @@ static int sirfsoc_dma_terminate_all(struct dma_chan *chan)
 	switch (sdma->type) {
 	case SIRFSOC_DMA_VER_A7V1:
 		writel_relaxed(1 << cid, sdma->base + SIRFSOC_DMA_INT_EN_CLR);
+		writel_relaxed(1 << cid, sdma->base + SIRFSOC_DMA_CH_INT);
 		writel_relaxed((1 << cid) | 1 << (cid + 16),
 			       sdma->base +
 			       SIRFSOC_DMA_CH_LOOP_CTRL_CLR_ATLAS7);
@@ -462,6 +463,8 @@ static int sirfsoc_dma_terminate_all(struct dma_chan *chan)
 		break;
 	case SIRFSOC_DMA_VER_A7V2:
 		writel_relaxed(0, sdma->base + SIRFSOC_DMA_INT_EN_ATLAS7);
+		writel_relaxed(SIRFSOC_DMA_INT_ALL_ATLAS7,
+			       sdma->base + SIRFSOC_DMA_INT_ATLAS7);
 		writel_relaxed(0, sdma->base + SIRFSOC_DMA_LOOP_CTRL_ATLAS7);
 		writel_relaxed(0, sdma->base + SIRFSOC_DMA_VALID_ATLAS7);
 		break;
-- 
2.3.5

[PATCH] dmaengine: sirf: fix kernel panic under one race condition

[Vinod Koul]

On Tue, Jul 14, 2015 at 12:28:25AM +0000, Barry Song wrote:
> From: Yanchang Li <yl22@csr.com>

patch title should alos say what is changed. "panic under one race" is not
an apt description for this

Can you fix that up, otherwise it looks okay

-- 
~Vinod

> 
> If DMA interrupt comes and is latched by IRQ controller during the
> execution of dma_terminate_all(), dma_irq routine will be executed
> after dma terminated, and it will cause kernel panic.
> We clear DMA interrupts in dma_terminate_all() to avoid this useless
> interrupt.
> 
> Signed-off-by: Yanchang Li <yl22@csr.com>
> Signed-off-by: Barry Song <Baohua.Song@csr.com>
> ---
>  drivers/dma/sirf-dma.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/dma/sirf-dma.c b/drivers/dma/sirf-dma.c
> index 8c5186c..7d5598d 100644
> --- a/drivers/dma/sirf-dma.c
> +++ b/drivers/dma/sirf-dma.c
> @@ -455,6 +455,7 @@ static int sirfsoc_dma_terminate_all(struct dma_chan *chan)
>  	switch (sdma->type) {
>  	case SIRFSOC_DMA_VER_A7V1:
>  		writel_relaxed(1 << cid, sdma->base + SIRFSOC_DMA_INT_EN_CLR);
> +		writel_relaxed(1 << cid, sdma->base + SIRFSOC_DMA_CH_INT);
>  		writel_relaxed((1 << cid) | 1 << (cid + 16),
>  			       sdma->base +
>  			       SIRFSOC_DMA_CH_LOOP_CTRL_CLR_ATLAS7);
> @@ -462,6 +463,8 @@ static int sirfsoc_dma_terminate_all(struct dma_chan *chan)
>  		break;
>  	case SIRFSOC_DMA_VER_A7V2:
>  		writel_relaxed(0, sdma->base + SIRFSOC_DMA_INT_EN_ATLAS7);
> +		writel_relaxed(SIRFSOC_DMA_INT_ALL_ATLAS7,
> +			       sdma->base + SIRFSOC_DMA_INT_ATLAS7);
>  		writel_relaxed(0, sdma->base + SIRFSOC_DMA_LOOP_CTRL_ATLAS7);
>  		writel_relaxed(0, sdma->base + SIRFSOC_DMA_VALID_ATLAS7);
>  		break;
> -- 
> 2.3.5
> 

-- 

[PATCH] dmaengine: sirf: fix kernel panic under one race condition

[Barry Song]

2015-07-16 21:17 GMT+08:00 Vinod Koul <vinod.koul@intel.com>:
> On Tue, Jul 14, 2015 at 12:28:25AM +0000, Barry Song wrote:
>> From: Yanchang Li <yl22@csr.com>
>
> patch title should alos say what is changed. "panic under one race" is not
> an apt description for this
>
> Can you fix that up, otherwise it looks okay
>

yes. it seems it can be

dmaengine: sirf: clear any pending DMA interrupt when DMA terminates

> --
> ~Vinod
>
>>
>> If DMA interrupt comes and is latched by IRQ controller during the
>> execution of dma_terminate_all(), dma_irq routine will be executed
>> after dma terminated, and it will cause kernel panic.
>> We clear DMA interrupts in dma_terminate_all() to avoid this useless
>> interrupt.
>>
>> Signed-off-by: Yanchang Li <yl22@csr.com>
>> Signed-off-by: Barry Song <Baohua.Song@csr.com>
>> ---
>>  drivers/dma/sirf-dma.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/dma/sirf-dma.c b/drivers/dma/sirf-dma.c
>> index 8c5186c..7d5598d 100644
>> --- a/drivers/dma/sirf-dma.c
>> +++ b/drivers/dma/sirf-dma.c
>> @@ -455,6 +455,7 @@ static int sirfsoc_dma_terminate_all(struct dma_chan *chan)
>>       switch (sdma->type) {
>>       case SIRFSOC_DMA_VER_A7V1:
>>               writel_relaxed(1 << cid, sdma->base + SIRFSOC_DMA_INT_EN_CLR);
>> +             writel_relaxed(1 << cid, sdma->base + SIRFSOC_DMA_CH_INT);
>>               writel_relaxed((1 << cid) | 1 << (cid + 16),
>>                              sdma->base +
>>                              SIRFSOC_DMA_CH_LOOP_CTRL_CLR_ATLAS7);
>> @@ -462,6 +463,8 @@ static int sirfsoc_dma_terminate_all(struct dma_chan *chan)
>>               break;
>>       case SIRFSOC_DMA_VER_A7V2:
>>               writel_relaxed(0, sdma->base + SIRFSOC_DMA_INT_EN_ATLAS7);
>> +             writel_relaxed(SIRFSOC_DMA_INT_ALL_ATLAS7,
>> +                            sdma->base + SIRFSOC_DMA_INT_ATLAS7);
>>               writel_relaxed(0, sdma->base + SIRFSOC_DMA_LOOP_CTRL_ATLAS7);
>>               writel_relaxed(0, sdma->base + SIRFSOC_DMA_VALID_ATLAS7);
>>               break;
>> --
>> 2.3.5
>>
>
-barry