* drivers/misc/habanalabs: atomic_t api usage inconsistencies
@ 2020-09-21 22:08 Shuah Khan
2020-09-23 8:41 ` Oded Gabbay
0 siblings, 1 reply; 3+ messages in thread
From: Shuah Khan @ 2020-09-21 22:08 UTC (permalink / raw)
To: oded.gabbay, Arnd Bergmann, Greg Kroah-Hartman, obitton,
lee.jones, oshpigelman
Cc: Linux Kernel Mailing List, Shuah Khan
All,
While I was looking at the atomic_t api usages for an unrelated issue,
I noticed free_slots_cnt in struct hl_cq incerment/decrement/reads are
not consistent.
atomic_inc() and atomic_set() are used, however instead of atomic_read()
the value is referenced directly in
drivers/misc/habanalabs/common/hw_queue.c
hl_queue_add_ptr()
atomic_t *free_slots = &hdev->completion_queue[q->cq_id].free_slots_cnt;
hl_hw_queue_schedule_cs()
atomic_t *free_slots = &hdev->completion_queue[i].free_slots_cnt;
Any reason why this is necessary. I don't know that this is causing
any problems, it is just odd that access is inconsistent.
thanks,
-- Shuah
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: drivers/misc/habanalabs: atomic_t api usage inconsistencies
2020-09-21 22:08 drivers/misc/habanalabs: atomic_t api usage inconsistencies Shuah Khan
@ 2020-09-23 8:41 ` Oded Gabbay
2020-09-23 19:38 ` Shuah Khan
0 siblings, 1 reply; 3+ messages in thread
From: Oded Gabbay @ 2020-09-23 8:41 UTC (permalink / raw)
To: Shuah Khan
Cc: Arnd Bergmann, Greg Kroah-Hartman, Ofir Bitton, Lee Jones,
Omer Shpigelman, Linux Kernel Mailing List
On Tue, Sep 22, 2020 at 1:08 AM Shuah Khan <skhan@linuxfoundation.org> wrote:
>
> All,
>
> While I was looking at the atomic_t api usages for an unrelated issue,
> I noticed free_slots_cnt in struct hl_cq incerment/decrement/reads are
> not consistent.
>
> atomic_inc() and atomic_set() are used, however instead of atomic_read()
> the value is referenced directly in
> drivers/misc/habanalabs/common/hw_queue.c
>
> hl_queue_add_ptr()
> atomic_t *free_slots = &hdev->completion_queue[q->cq_id].free_slots_cnt;
>
> hl_hw_queue_schedule_cs()
>
> atomic_t *free_slots = &hdev->completion_queue[i].free_slots_cnt;
>
> Any reason why this is necessary. I don't know that this is causing
> any problems, it is just odd that access is inconsistent.
>
> thanks,
> -- Shuah
Hi Shuah,
Thanks for taking notice of this issue :)
We will take a deeper look and fix the inconsistencies, although I
must say that we didn't notice any impact of this issue.
Thanks again.
Oded
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: drivers/misc/habanalabs: atomic_t api usage inconsistencies
2020-09-23 8:41 ` Oded Gabbay
@ 2020-09-23 19:38 ` Shuah Khan
0 siblings, 0 replies; 3+ messages in thread
From: Shuah Khan @ 2020-09-23 19:38 UTC (permalink / raw)
To: Oded Gabbay
Cc: Arnd Bergmann, Greg Kroah-Hartman, Ofir Bitton, Lee Jones,
Omer Shpigelman, Linux Kernel Mailing List, Shuah Khan
On 9/23/20 2:41 AM, Oded Gabbay wrote:
> On Tue, Sep 22, 2020 at 1:08 AM Shuah Khan <skhan@linuxfoundation.org> wrote:
>>
>> All,
>>
>> While I was looking at the atomic_t api usages for an unrelated issue,
>> I noticed free_slots_cnt in struct hl_cq incerment/decrement/reads are
>> not consistent.
>>
>> atomic_inc() and atomic_set() are used, however instead of atomic_read()
>> the value is referenced directly in
>> drivers/misc/habanalabs/common/hw_queue.c
>>
>> hl_queue_add_ptr()
>> atomic_t *free_slots = &hdev->completion_queue[q->cq_id].free_slots_cnt;
>>
>> hl_hw_queue_schedule_cs()
>>
>> atomic_t *free_slots = &hdev->completion_queue[i].free_slots_cnt;
>>
>> Any reason why this is necessary. I don't know that this is causing
>> any problems, it is just odd that access is inconsistent.
>>
>> thanks,
>> -- Shuah
>
> Hi Shuah,
> Thanks for taking notice of this issue :)
> We will take a deeper look and fix the inconsistencies, although I
> must say that we didn't notice any impact of this issue.
If you haven't noticed any problems, it could be that this variable
doesn't need to atomic or you haven't run into it yet?
thanks,
-- Shuah
^ permalink raw reply [flat|nested] 3+ messages in thread
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