Re: [PATCH net-next v3] net: sched: act_gact: use acquire/release for tcfg_ptype

[Jinjie Ruan]

在 2026/9/6 4:42, Jakub Kicinski 写道:
> On Wed, 2 Sep 2026 15:16:59 +0800 Jinjie Ruan wrote:
>> @@ -160,7 +155,8 @@ TC_INDIRECT_SCOPE int tcf_gact_act(struct sk_buff *skb,
>>  
>>  #ifdef CONFIG_GACT_PROB
>>  	{
>> -	u32 ptype = READ_ONCE(gact->tcfg_ptype);
>> +	/* Pairs with smp_store_release() in tcf_gact_init() */
>> +	u32 ptype = smp_load_acquire(&gact->tcfg_ptype);
>>  
>>  	if (ptype)
>>  		action = gact_rand[ptype](gact);
> 
> Clashiko points out that you are turning what used to be a conditional
> barrier into one that's always obeyed, even if ptype is 0.

What do you think of the following fix?

 #ifdef CONFIG_GACT_PROB
        {
-       u32 ptype = READ_ONCE(gact->tcfg_ptype);
+               u32 ptype = READ_ONCE(gact->tcfg_ptype);

-       if (ptype)
-               action = gact_rand[ptype](gact);
+               if (ptype) {
+                       /* Pairs with smp_store_release() in
tcf_gact_init() */
+                       ptype = smp_load_acquire(&gact->tcfg_ptype);
+                       if (ptype)
+                               action = gact_rand[ptype](gact);
+               }
        }