On 10/14/2024 12:04 PM, David Laight wrote:
> From: Jacob Keller
>> Sent: 14 October 2024 19:51
>>
>> On 10/12/2024 8:13 AM, Simon Horman wrote:
>>> + David Laight
>>>
>>> On Mon, Sep 30, 2024 at 02:03:57PM +0200, Michal Swiatkowski wrote:
>>>> Remove the field to allow having more queues than MSI-X on VSI. As
>>>> default the number will be the same, but if there won't be more MSI-X
>>>> available VSI can run with at least one MSI-X.
>>>>
>>>> Reviewed-by: Wojciech Drewek <wojciech.dre...@intel.com>
>>>> Signed-off-by: Michal Swiatkowski <michal.swiatkow...@linux.intel.com>
>>>> ---
>>>> drivers/net/ethernet/intel/ice/ice.h | 1 -
>>>> drivers/net/ethernet/intel/ice/ice_base.c | 10 +++-----
>>>> drivers/net/ethernet/intel/ice/ice_ethtool.c | 8 +++---
>>>> drivers/net/ethernet/intel/ice/ice_irq.c | 11 +++------
>>>> drivers/net/ethernet/intel/ice/ice_lib.c | 26 +++++++++++---------
>>>> 5 files changed, 27 insertions(+), 29 deletions(-)
>>>>
>>>> diff --git a/drivers/net/ethernet/intel/ice/ice.h
>>>> b/drivers/net/ethernet/intel/ice/ice.h
>>>> index cf824d041d5a..1e23aec2634f 100644
>>>> --- a/drivers/net/ethernet/intel/ice/ice.h
>>>> +++ b/drivers/net/ethernet/intel/ice/ice.h
>>>> @@ -622,7 +622,6 @@ struct ice_pf {
>>>> u16 max_pf_txqs; /* Total Tx queues PF wide */
>>>> u16 max_pf_rxqs; /* Total Rx queues PF wide */
>>>> struct ice_pf_msix msix;
>>>> - u16 num_lan_msix; /* Total MSIX vectors for base driver */
>>>> u16 num_lan_tx; /* num LAN Tx queues setup */
>>>> u16 num_lan_rx; /* num LAN Rx queues setup */
>>>> u16 next_vsi; /* Next free slot in pf->vsi[] - 0-based! */
>>>
>>> ...
>>>
>>>> diff --git a/drivers/net/ethernet/intel/ice/ice_ethtool.c
>> b/drivers/net/ethernet/intel/ice/ice_ethtool.c
>>>> index 85a3b2326e7b..e5c56ec8bbda 100644
>>>> --- a/drivers/net/ethernet/intel/ice/ice_ethtool.c
>>>> +++ b/drivers/net/ethernet/intel/ice/ice_ethtool.c
>>>> @@ -3811,8 +3811,8 @@ ice_get_ts_info(struct net_device *dev, struct
>>>> kernel_ethtool_ts_info *info)
>>>> */
>>>> static int ice_get_max_txq(struct ice_pf *pf)
>>>> {
>>>> - return min3(pf->num_lan_msix, (u16)num_online_cpus(),
>>>> - (u16)pf->hw.func_caps.common_cap.num_txq);
>>>> + return min_t(u16, num_online_cpus(),
>>>> + pf->hw.func_caps.common_cap.num_txq);
>>>
>>> It is unclear why min_t() is used here or elsewhere in this patch
>>> instead of min() as it seems that all the entities being compared
>>> are unsigned. Are you concerned about overflowing u16? If so, perhaps
>>> clamp, or some error handling, is a better approach.
>>>
>>> I am concerned that the casting that min_t() brings will hide
>>> any problems that may exist.
>>>
>> Ya, I think min makes more sense. min_t was likely selected out of habit
>> or looking at other examples in the driver.
>
> My 'spot patches that use min_t()' failed to spot that one.
>
> But it is just plain wrong - and always was.
> You want a result that is 16bits, casting the inputs is wrong.
> Consider a system with 64k cpus!
>
Yea, that makes sense. This is definitely not going to behave well in
the event that one of the values is above 16-bit.
> Pretty much all the min_t() that specify u8 or u16 are likely to
> be actually broken.
> Most of the rest specify u32 or u64 in order to compare (usually)
> unsigned values of different sizes.
> But I found some that might be using 'long' on 64bit values
> on 32bit (and as disk sector numbers!).
>
> In the current min() bleats, the code is almost certainly awry.
>
> David
