Re: [PATCH for-next 2/3] IB/core: Change per-entry lock in RoCE GID table to one lock

[Matan Barak <matanb-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>]

On 12/30/2015 9:36 AM, Bart Van Assche wrote:
> On 12/30/2015 07:01 AM, Or Gerlitz wrote:
>> On 10/28/2015 4:52 PM, Matan Barak wrote:
>>> @@ -134,16 +138,14 @@ static int write_gid(struct ib_device *ib_dev,
>>> u8 port,
>>>   {
>>>       int ret = 0;
>>>       struct net_device *old_net_dev;
>>> -    unsigned long flags;
>>>       /* in rdma_cap_roce_gid_table, this funciton should be protected
>>> by a
>>>        * sleep-able lock.
>>>        */
>>> -    write_lock_irqsave(&table->data_vec[ix].lock, flags);
>>>       if (rdma_cap_roce_gid_table(ib_dev, port)) {
>>>           table->data_vec[ix].props |= GID_TABLE_ENTRY_INVALID;
>>> -        write_unlock_irqrestore(&table->data_vec[ix].lock, flags);
>>> +        write_unlock_irq(&table->rwlock);
>>>           /* GID_TABLE_WRITE_ACTION_MODIFY currently isn't supported by
>>>            * RoCE providers and thus only updates the cache.
>>>            */
>>> @@ -153,7 +155,7 @@ static int write_gid(struct ib_device *ib_dev, u8
>>> port,
>>>           else if (action == GID_TABLE_WRITE_ACTION_DEL)
>>>               ret = ib_dev->del_gid(ib_dev, port, ix,
>>>                             &table->data_vec[ix].context);
>>> -        write_lock_irqsave(&table->data_vec[ix].lock, flags);
>>> +        write_lock_irq(&table->rwlock);
>>>       }
>>
>> sparse complains on
>>
>> drivers/infiniband/core/cache.c:186:17: warning: context imbalance in
>> 'write_gid' - unexpected unlock
>>
>> is this false positive?
>

It is false positive.

> Hello Or,
>
> sparse expects __release() and __acquire() annotations for functions
> that unlock a lock object that has been locked by its caller. See e.g.
> http://lists.kernelnewbies.org/pipermail/kernelnewbies/2011-October/003541.html.
>

Thanks - adding __releases and __acquires eliminates this sparse warning.

>
> Bart.

Matan
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