[PATCH] drm/amdkfd: use time_is_before_jiffies(a + b) to replace "jiffies - a > b"

[PATCH] drm/amdkfd: use time_is_before_jiffies(a + b) to replace "jiffies - a > b"

[Yu Zhe]

time_is_before_jiffies deals with timer wrapping correctly.

Signed-off-by: Yu Zhe <yuzhe@nfschina.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
index a9466d154395..6397926e059c 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
@@ -156,7 +156,7 @@ static void interrupt_wq(struct work_struct *work)
 	while (dequeue_ih_ring_entry(dev, ih_ring_entry)) {
 		dev->device_info.event_interrupt_class->interrupt_wq(dev,
 								ih_ring_entry);
-		if (jiffies - start_jiffies > HZ) {
+		if (time_is_before_jiffies(start_jiffies + HZ)) {
 			/* If we spent more than a second processing signals,
 			 * reschedule the worker to avoid soft-lockup warnings
 			 */
-- 
2.11.0

Re: [PATCH] drm/amdkfd: use time_is_before_jiffies(a + b) to replace "jiffies - a > b"

[Felix Kuehling]

This patch introduces a build warning for me:

   CC [M]  drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_interrupt.o
In file included from /home/fkuehlin/compute/kernel/include/linux/spinlock.h:54,
                  from /home/fkuehlin/compute/kernel/include/linux/mmzone.h:8,
                  from /home/fkuehlin/compute/kernel/include/linux/gfp.h:6,
                  from /home/fkuehlin/compute/kernel/include/linux/slab.h:15,
                  from /home/fkuehlin/compute/kernel/drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_interrupt.c:44:
/home/fkuehlin/compute/kernel/drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_interrupt.c: In function ?interrupt_wq?:
/home/fkuehlin/compute/kernel/include/linux/typecheck.h:12:18: warning: comparison of distinct pointer types lacks a cast
    12 |  (void)(&__dummy == &__dummy2); \
       |                  ^~
/home/fkuehlin/compute/kernel/include/linux/jiffies.h:106:3: note: in expansion of macro ?typecheck?
   106 |   typecheck(unsigned long, b) && \
       |   ^~~~~~~~~
/home/fkuehlin/compute/kernel/include/linux/jiffies.h:154:35: note: in expansion of macro ?time_after?
   154 | #define time_is_before_jiffies(a) time_after(jiffies, a)
       |                                   ^~~~~~~~~~
/home/fkuehlin/compute/kernel/drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_interrupt.c:159:7: note: in expansion of macro ?time_is_before_jiffies?
   159 |   if (time_is_before_jiffies(start_jiffies + HZ)) {
       |       ^~~~~~~~~~~~~~~~~~~~~~

I think you need to change the the definition of start_jiffies to be 
unsigned long. Do you want to submit a v2 of your patch?

That said, I think the existing code was fine, though the type-mismatch 
highlighted by your patch is a bit iffy.

Regards,
   Felix


Am 2022-07-26 um 22:59 schrieb Yu Zhe:
> time_is_before_jiffies deals with timer wrapping correctly.
>
> Signed-off-by: Yu Zhe <yuzhe@nfschina.com>
> ---
>   drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
> index a9466d154395..6397926e059c 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
> @@ -156,7 +156,7 @@ static void interrupt_wq(struct work_struct *work)
>   	while (dequeue_ih_ring_entry(dev, ih_ring_entry)) {
>   		dev->device_info.event_interrupt_class->interrupt_wq(dev,
>   								ih_ring_entry);
> -		if (jiffies - start_jiffies > HZ) {
> +		if (time_is_before_jiffies(start_jiffies + HZ)) {
>   			/* If we spent more than a second processing signals,
>   			 * reschedule the worker to avoid soft-lockup warnings
>   			 */

Re: [PATCH] drm/amdkfd: use time_is_before_jiffies(a + b) to replace "jiffies - a > b"

[Yu Zhe]

在 2022年07月28日 00:04, Felix Kuehling 写道:

> This patch introduces a build warning for me:
>    CC [M]  drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_interrupt.o
> In file included from /home/fkuehlin/compute/kernel/include/linux/spinlock.h:54,
>                   from /home/fkuehlin/compute/kernel/include/linux/mmzone.h:8,
>                   from /home/fkuehlin/compute/kernel/include/linux/gfp.h:6,
>                   from /home/fkuehlin/compute/kernel/include/linux/slab.h:15,
>                   from /home/fkuehlin/compute/kernel/drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_interrupt.c:44:
> /home/fkuehlin/compute/kernel/drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_interrupt.c: In function ?interrupt_wq?:
> /home/fkuehlin/compute/kernel/include/linux/typecheck.h:12:18: warning: comparison of distinct pointer types lacks a cast
>     12 |  (void)(&__dummy == &__dummy2); \
>        |                  ^~
> /home/fkuehlin/compute/kernel/include/linux/jiffies.h:106:3: note: in expansion of macro ?typecheck?
>    106 |   typecheck(unsigned long, b) && \
>        |   ^~~~~~~~~
> /home/fkuehlin/compute/kernel/include/linux/jiffies.h:154:35: note: in expansion of macro ?time_after?
>    154 | #define time_is_before_jiffies(a) time_after(jiffies, a)
>        |                                   ^~~~~~~~~~
> /home/fkuehlin/compute/kernel/drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_interrupt.c:159:7: note: in expansion of macro ?time_is_before_jiffies?
>    159 |   if (time_is_before_jiffies(start_jiffies + HZ)) {
>        |       ^~~~~~~~~~~~~~~~~~~~~~
> I think you need to change the the definition of start_jiffies to be
> unsigned long. Do you want to submit a v2 of your patch?

Yes, I will submit v2 patch later.

> That said, I think the existing code was fine, though the type-mismatch
> highlighted by your patch is a bit iffy.

And if the timer wrap changes in the future you won't have to alter your driver code. So I think it's better.

> Regards,
>    Felix
> Am 2022-07-26 um 22:59 schrieb Yu Zhe:
>> time_is_before_jiffies deals with timer wrapping correctly.
>> Signed-off-by: Yu Zhe <yuzhe@nfschina.com>
>> ---
>>    drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c | 2 +-
>>    1 file changed, 1 insertion(+), 1 deletion(-)
>> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
>> index a9466d154395..6397926e059c 100644
>> --- a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
>> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
>> @@ -156,7 +156,7 @@ static void interrupt_wq(struct work_struct *work)
>>        while (dequeue_ih_ring_entry(dev, ih_ring_entry)) {
>>            dev->device_info.event_interrupt_class->interrupt_wq(dev,
>>                                    ih_ring_entry);
>> -        if (jiffies - start_jiffies > HZ) {
>> +        if (time_is_before_jiffies(start_jiffies + HZ)) {
>>                /* If we spent more than a second processing signals,
>>                 * reschedule the worker to avoid soft-lockup warnings
>>                 */
>

[PATCH v2] drm/amdkfd: use time_is_before_jiffies(a + b) to replace "jiffies - a > b"

[Yu Zhe]

time_is_before_jiffies deals with timer wrapping correctly.

Signed-off-by: Yu Zhe <yuzhe@nfschina.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
index a9466d154395..34772fe74296 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
@@ -146,7 +146,7 @@ static void interrupt_wq(struct work_struct *work)
 	struct kfd_dev *dev = container_of(work, struct kfd_dev,
 						interrupt_work);
 	uint32_t ih_ring_entry[KFD_MAX_RING_ENTRY_SIZE];
-	long start_jiffies = jiffies;
+	unsigned long start_jiffies = jiffies;
 
 	if (dev->device_info.ih_ring_entry_size > sizeof(ih_ring_entry)) {
 		dev_err_once(dev->adev->dev, "Ring entry too small\n");
@@ -156,7 +156,7 @@ static void interrupt_wq(struct work_struct *work)
 	while (dequeue_ih_ring_entry(dev, ih_ring_entry)) {
 		dev->device_info.event_interrupt_class->interrupt_wq(dev,
 								ih_ring_entry);
-		if (jiffies - start_jiffies > HZ) {
+		if (time_is_before_jiffies(start_jiffies + HZ)) {
 			/* If we spent more than a second processing signals,
 			 * reschedule the worker to avoid soft-lockup warnings
 			 */
-- 
2.11.0

Re: [PATCH v2] drm/amdkfd: use time_is_before_jiffies(a + b) to replace "jiffies - a > b"

[Felix Kuehling]

Am 2022-07-27 um 23:30 schrieb Yu Zhe:
> time_is_before_jiffies deals with timer wrapping correctly.
>
> Signed-off-by: Yu Zhe <yuzhe@nfschina.com>

Thank you. This patch looks good to me. I'm applying it to 
amd-staging-drm-next.

Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>


> ---
>   drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
> index a9466d154395..34772fe74296 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
> @@ -146,7 +146,7 @@ static void interrupt_wq(struct work_struct *work)
>   	struct kfd_dev *dev = container_of(work, struct kfd_dev,
>   						interrupt_work);
>   	uint32_t ih_ring_entry[KFD_MAX_RING_ENTRY_SIZE];
> -	long start_jiffies = jiffies;
> +	unsigned long start_jiffies = jiffies;
>   
>   	if (dev->device_info.ih_ring_entry_size > sizeof(ih_ring_entry)) {
>   		dev_err_once(dev->adev->dev, "Ring entry too small\n");
> @@ -156,7 +156,7 @@ static void interrupt_wq(struct work_struct *work)
>   	while (dequeue_ih_ring_entry(dev, ih_ring_entry)) {
>   		dev->device_info.event_interrupt_class->interrupt_wq(dev,
>   								ih_ring_entry);
> -		if (jiffies - start_jiffies > HZ) {
> +		if (time_is_before_jiffies(start_jiffies + HZ)) {
>   			/* If we spent more than a second processing signals,
>   			 * reschedule the worker to avoid soft-lockup warnings
>   			 */