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Message-ID: <0e9ae896-82c1-6ddb-c1a0-e233f8a9d7f0@intel.com>
Date: Fri, 23 Jun 2023 16:28:08 +0200
From: Przemek Kitszel <przemyslaw.kitszel@...el.com>
To: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
CC: Tony Nguyen <anthony.l.nguyen@...el.com>, <davem@...emloft.net>,
	<kuba@...nel.org>, <pabeni@...hat.com>, <edumazet@...gle.com>,
	<netdev@...r.kernel.org>, Michal Swiatkowski
	<michal.swiatkowski@...ux.intel.com>, Michal Wilczynski
	<michal.wilczynski@...el.com>, Simon Horman <simon.horman@...igine.com>,
	Arpana Arland <arpanax.arland@...el.com>
Subject: Re: [PATCH net-next 4/6] ice: remove null checks before devm_kfree()
 calls

On 6/23/23 15:25, Maciej Fijalkowski wrote:
> On Fri, Jun 23, 2023 at 03:21:30PM +0200, Przemek Kitszel wrote:
>> On 6/23/23 13:13, Maciej Fijalkowski wrote:
>>> On Fri, Jun 23, 2023 at 12:44:29PM +0200, Przemek Kitszel wrote:
>>>> On 6/23/23 12:23, Maciej Fijalkowski wrote:
>>>>> On Thu, Jun 22, 2023 at 11:35:59AM -0700, Tony Nguyen wrote:
>>>>>> From: Przemek Kitszel <przemyslaw.kitszel@...el.com>
>>>>>>
>>>>>> We all know they are redundant.
>>>>>
>>>>> Przemek,
>>>>>
>>>>> Ok, they are redundant, but could you also audit the driver if these devm_
>>>>> allocations could become a plain kzalloc/kfree calls?
>>>>
>>>> Olek was also motivating such audit :)
>>>>
>>>> I have some cases collected with intention to send in bulk for next window,
>>>> list is not exhaustive though.
>>>
>>> When rev-by count tag would be considered too much? I have a mixed
>>> feelings about providing yet another one, however...
>>>
>>>>
>>>>>
>>>>>>
>>>>>> Reviewed-by: Michal Swiatkowski <michal.swiatkowski@...ux.intel.com>
>>>>>> Reviewed-by: Michal Wilczynski <michal.wilczynski@...el.com>
>>>>>> Reviewed-by: Simon Horman <simon.horman@...igine.com>
>>>>>> Signed-off-by: Przemek Kitszel <przemyslaw.kitszel@...el.com>
>>>>>> Tested-by: Arpana Arland <arpanax.arland@...el.com> (A Contingent worker at Intel)
>>>>>> Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
>>>>>> ---
>>>>>>     drivers/net/ethernet/intel/ice/ice_common.c   |  6 +--
>>>>>>     drivers/net/ethernet/intel/ice/ice_controlq.c |  3 +-
>>>>>>     drivers/net/ethernet/intel/ice/ice_flow.c     | 23 ++--------
>>>>>>     drivers/net/ethernet/intel/ice/ice_lib.c      | 42 +++++++------------
>>>>>>     drivers/net/ethernet/intel/ice/ice_sched.c    | 11 ++---
>>>>>>     drivers/net/ethernet/intel/ice/ice_switch.c   | 19 +++------
>>>>>>     6 files changed, 29 insertions(+), 75 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/net/ethernet/intel/ice/ice_common.c b/drivers/net/ethernet/intel/ice/ice_common.c
>>>>>> index eb2dc0983776..6acb40f3c202 100644
>>>>>> --- a/drivers/net/ethernet/intel/ice/ice_common.c
>>>>>> +++ b/drivers/net/ethernet/intel/ice/ice_common.c
>>>>>> @@ -814,8 +814,7 @@ static void ice_cleanup_fltr_mgmt_struct(struct ice_hw *hw)
>>>>>>     				devm_kfree(ice_hw_to_dev(hw), lst_itr);
>>>>>>     			}
>>>>>>     		}
>>>>>> -		if (recps[i].root_buf)
>>>>>> -			devm_kfree(ice_hw_to_dev(hw), recps[i].root_buf);
>>>>>> +		devm_kfree(ice_hw_to_dev(hw), recps[i].root_buf);
>>>>>>     	}
>>>>>>     	ice_rm_all_sw_replay_rule_info(hw);
>>>>>>     	devm_kfree(ice_hw_to_dev(hw), sw->recp_list);
>>>>>> @@ -1011,8 +1010,7 @@ static int ice_cfg_fw_log(struct ice_hw *hw, bool enable)
>>>>>>     	}
>>>>>>     out:
>>>>>> -	if (data)
>>>>>> -		devm_kfree(ice_hw_to_dev(hw), data);
>>>>>> +	devm_kfree(ice_hw_to_dev(hw), data);
>>>>>>     	return status;
>>>>>>     }
>>>>>> diff --git a/drivers/net/ethernet/intel/ice/ice_controlq.c b/drivers/net/ethernet/intel/ice/ice_controlq.c
>>>>>> index 385fd88831db..e7d2474c431c 100644
>>>>>> --- a/drivers/net/ethernet/intel/ice/ice_controlq.c
>>>>>> +++ b/drivers/net/ethernet/intel/ice/ice_controlq.c
>>>>>> @@ -339,8 +339,7 @@ do {									\
>>>>>>     		}							\
>>>>>>     	}								\
>>>>>>     	/* free the buffer info list */					\
>>>>>> -	if ((qi)->ring.cmd_buf)						\
>>>>>> -		devm_kfree(ice_hw_to_dev(hw), (qi)->ring.cmd_buf);	\
>>>>>> +	devm_kfree(ice_hw_to_dev(hw), (qi)->ring.cmd_buf);		\
>>>>>>     	/* free DMA head */						\
>>>>>>     	devm_kfree(ice_hw_to_dev(hw), (qi)->ring.dma_head);		\
>>>>>>     } while (0)
>>>>>> diff --git a/drivers/net/ethernet/intel/ice/ice_flow.c b/drivers/net/ethernet/intel/ice/ice_flow.c
>>>>>> index ef103e47a8dc..85cca572c22a 100644
>>>>>> --- a/drivers/net/ethernet/intel/ice/ice_flow.c
>>>>>> +++ b/drivers/net/ethernet/intel/ice/ice_flow.c
>>>>>> @@ -1303,23 +1303,6 @@ ice_flow_find_prof_id(struct ice_hw *hw, enum ice_block blk, u64 prof_id)
>>>>>>     	return NULL;
>>>>>>     }
>>>>>> -/**
>>>>>> - * ice_dealloc_flow_entry - Deallocate flow entry memory
>>>>>> - * @hw: pointer to the HW struct
>>>>>> - * @entry: flow entry to be removed
>>>>>> - */
>>>>>> -static void
>>>>>> -ice_dealloc_flow_entry(struct ice_hw *hw, struct ice_flow_entry *entry)
>>>>>> -{
>>>>>> -	if (!entry)
>>>>>> -		return;
>>>>>> -
>>>>>> -	if (entry->entry)
>>>
>>> ...would you be able to point me to the chunk of code that actually sets
>>> ice_flow_entry::entry? because from a quick glance I can't seem to find
>>> it.
>>
>> Simon was asking very similar question [1],
>> albeit "where is the *check* for entry not being null?" (not set),
>> and it is just above the default three lines of context provided by git
>> (pasted below for your convenience, [3])
>>
>> To answer, "where it's set?", see ice_flow_add_entry(), [2].
> 
> I was referring to 'entry' member from ice_flow_entry struct. You're
> pointing me to init of whole ice_flow_entry.
> 
> I am trying to say that if ice_flow_entry::entry is never set, then
> probably it could be removed from struct.

You are totally right, I have compile-checked it and that's good idea.
I will post a followup patch for that.

The field itself originates from One Of The our internal demo drivers (:T)

> 
>>
>> [1] https://lore.kernel.org/netdev/ZHb5AIgL5SzBa5FA@corigine.com/
>> [2] https://elixir.bootlin.com/linux/v6.4-rc7/source/drivers/net/ethernet/intel/ice/ice_flow.c#L1632
>>
>> --
>>
>> BTW, is there any option to add some of patch generation options (like,
>> context size, anchored lines, etc), that there are my disposal locally, but
>> in a way, that it would not be lost after patch is applied to one tree
>> (Tony's) and then send again (here)?
>> (My assumption is that Tony is (re)generating patches from git (opposed to
>> copy-pasting+decorating of what he has received from me).
>>
>>
>>
>>>
>>>>>> -		devm_kfree(ice_hw_to_dev(hw), entry->entry);
>>>>>> -
>>>>>> -	devm_kfree(ice_hw_to_dev(hw), entry);
>>>>>> -}
>>>>>> -
>>>>>>     /**
>>>>>>      * ice_flow_rem_entry_sync - Remove a flow entry
>>>>>>      * @hw: pointer to the HW struct
>>>>>> @@ -1335,7 +1318,8 @@ ice_flow_rem_entry_sync(struct ice_hw *hw, enum ice_block __always_unused blk,
>>
>> [3] More context would include following:
>>
>>           if (!entry)
>>                   return -EINVAL;
>>
>>>>>>     	list_del(&entry->l_entry);
>>>>>> -	ice_dealloc_flow_entry(hw, entry);
>>>>>> +	devm_kfree(ice_hw_to_dev(hw), entry->entry);
>>>>>> +	devm_kfree(ice_hw_to_dev(hw), entry);
>>>>>>     	return 0;
>>>>>>     }
>>>>>> @@ -1662,8 +1646,7 @@ ice_flow_add_entry(struct ice_hw *hw, enum ice_block blk, u64 prof_id,
>>>>>>     out:
>>>>>>     	if (status && e) {
>>>>>> -		if (e->entry)
>>>>>> -			devm_kfree(ice_hw_to_dev(hw), e->entry);
>>>>>> +		devm_kfree(ice_hw_to_dev(hw), e->entry);
>>>>>>     		devm_kfree(ice_hw_to_dev(hw), e);
>>>>>>     	}
>>>
>>> (...)
>>


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