Subject: Re: [PATCH] INET : removes per bucket rwlock in tcp/dccp ehash table

From: Eric Dumazet <[email-masked]>
Date: Sun, 04 Nov 2007 22:23:10 +0100

Jarek Poplawski a écrit :
> Jarek Poplawski wrote, On 11/04/2007 06:58 PM:
> 
>> Eric Dumazet wrote, On 11/04/2007 12:31 PM:
> 
> ...
> 
>>> +static inline int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo)
>>> +{
> 
> ...
> 
>>> +	if (sizeof(rwlock_t) != 0) {
> 
> ...
> 
>>> +		for (i = 0; i < size; i++)
>>> +			rwlock_init(&hashinfo->ehash_locks[i]);
>>
>> This looks better now, but still is doubtful to me: even if it's safe with
>> current rwlock implementation, can't we imagine some new debugging or
>> statistical code added, which would be called from rwlock_init() without
>> using rwlock_t structure? IMHO, if read_lock() etc. are called in such a
>> case, rwlock_init() should be done as well.
> 
> 
> Of course I mean: if sizeof(rwlock_t) == 0.

Given those two choices :

#if defined(CONFIG_SMP) || defined(CONFIG_PROVE__LOCKING)
     kmalloc(sizeof(rwlock_t) * size);
#endif

and

    if (sizeof(rwlock_t) != 0) {
        kmalloc(sizeof(rwlock_t) * size);
    }

I prefer the 2nd one. Less error prone, and no need to remember how are 
spelled the gazillions CONFIG_something we have.