On 1/27/21 3:51 AM, Amit Cohen wrote:
>
>
>> -----Original Message-----
>> From: David Ahern <dsah...@gmail.com>
>> Sent: Wednesday, January 27, 2021 6:33
>> To: Ido Schimmel <ido...@idosch.org>; netdev@vger.kernel.org
>> Cc: da...@davemloft.net; k...@kernel.org; Amit Cohen <amco...@nvidia.com>;
>> Roopa Prabhu <ro...@nvidia.com>; Donald
>> Sharp <sha...@nvidia.com>; Benjamin Poirier <bpoir...@nvidia.com>; mlxsw
>> <ml...@nvidia.com>; Ido Schimmel
>> <ido...@nvidia.com>
>> Subject: Re: [PATCH net-next 01/10] netdevsim: fib: Convert the current
>> occupancy to an atomic variable
>>
>> On 1/26/21 6:23 AM, Ido Schimmel wrote:
>>> @@ -889,22 +882,29 @@ static void nsim_nexthop_destroy(struct
>>> nsim_nexthop *nexthop) static int nsim_nexthop_account(struct
>>> nsim_fib_data *data, u64 occ,
>>> bool add, struct netlink_ext_ack *extack) {
>>> - int err = 0;
>>> + int i, err = 0;
>>>
>>> if (add) {
>>> - if (data->nexthops.num + occ <= data->nexthops.max) {
>>> - data->nexthops.num += occ;
>>> - } else {
>>> - err = -ENOSPC;
>>> - NL_SET_ERR_MSG_MOD(extack, "Exceeded number of
>>> supported nexthops");
>>> - }
>>> + for (i = 0; i < occ; i++)
>>> + if (!atomic64_add_unless(&data->nexthops.num, 1,
>>> + data->nexthops.max)) {
>>
>> seems like this can be
>> if (!atomic64_add_unless(&data->nexthops.num, occ,
>> data->nexthops.max)) {
>
> atomic64_add_unless(x, y, z) adds y to x if x was not already z.
> Which means that when for example num=2, occ=2, max=3:
> atomic64_add_unless(&data->nexthops.num, occ, data->nexthops.max) won't fail
> when it should.
>
ok, missed that in the description. I thought it was if the total would
equal or be greater than z.
