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Date: Sun, 29 Jul 2007 13:21:15 -0700
From: Corey Hickey <bugfood-ml@...ooh.org>
To: Michael Buesch <mb@...sch.de>
CC: Linux Netdev List <netdev@...r.kernel.org>
Subject: Re: [PATCH 4/7] Add "depth".
Michael Buesch wrote:
> On Sunday 29 July 2007 09:08:51 Corey Hickey wrote:
>> p = d;
>> n = q->dep[d].next;
>> @@ -215,7 +216,7 @@ static unsigned int sfq_drop(struct Qdisc *sch)
>> drop a packet from it */
>>
>> if (d > 1) {
>> - sfq_index x = q->dep[d+SFQ_DEPTH].next;
>> + sfq_index x = q->dep[d+q->depth].next;
>
> Please q->dep[d + q->depth]
> Makes it _much_ more readable. And doesn't confuse my brain with a
> minus and a BiggerThan sign ;)
Ok.
>> @@ -383,6 +384,16 @@ static void sfq_perturbation(unsigned long arg)
>> static void sfq_q_destroy(struct sfq_sched_data *q)
>> {
>> del_timer(&q->perturb_timer);
>> + if(q->dep)
>> + kfree(q->dep);
>> + if(q->next)
>> + kfree(q->next);
>> + if(q->allot)
>> + kfree(q->allot);
>> + if(q->hash)
>> + kfree(q->hash);
>> + if(q->qs)
>> + kfree(q->qs);
>
> No need to check for !=NULL. kfree handles NULL.
Ok. Thanks.
>> }
>>
>> static void sfq_destroy(struct Qdisc *sch)
>> @@ -394,6 +405,7 @@ static void sfq_destroy(struct Qdisc *sch)
>> static int sfq_q_init(struct sfq_sched_data *q, struct rtattr *opt)
>> {
>> struct tc_sfq_qopt *ctl = RTA_DATA(opt);
>> + sfq_index p = ~0U/2;
>> int i;
>>
>> if (opt && opt->rta_len < RTA_LENGTH(sizeof(*ctl)))
>> @@ -401,30 +413,53 @@ static int sfq_q_init(struct sfq_sched_data *q, struct rtattr *opt)
>>
>> q->perturbation = 0;
>> q->max_depth = 0;
>> - q->tail = q->limit = SFQ_DEPTH;
>> if (opt == NULL) {
>> q->perturb_period = 0;
>> + q->tail = q->limit = q->depth = SFQ_DEPTH_DEFAULT;
>> } else {
>> struct tc_sfq_qopt *ctl = RTA_DATA(opt);
>> if (ctl->quantum)
>> q->quantum = ctl->quantum;
>> q->perturb_period = ctl->perturb_period*HZ;
>> + q->tail = q->limit = q->depth = ctl->flows ? : SFQ_DEPTH_DEFAULT;
>> +
>> + if (q->depth > p - 1)
>> + return -EINVAL;
>
> Compare depth against (~0U/2)-1? What's that doing? Should probably add a comment.
~0U/2 - 1 is the maximum value depth can be, based on how it is used in
indexing q->dep. I agree, though, that deserves a comment. Actually,
I'll also change it to '#define SFQ_DEPTH_MAX (~0U/2 - 1)' and put it
near the top of the file next to the 'typedef unsigned int sfq_index;'.
I could also include limits.h and use UINT_MAX instead of ~0U; would
that be preferable?
>>
>> if (ctl->limit)
>> - q->limit = min_t(u32, ctl->limit, SFQ_DEPTH);
>> + q->limit = min_t(u32, ctl->limit, q->depth);
>> }
>>
>> + q->dep = kmalloc((1+q->depth*2)*sizeof(struct sfq_head), GFP_KERNEL);
>> + if (!q->dep)
>> + goto err_case;
>> + q->next = kmalloc(q->depth*sizeof(sfq_index), GFP_KERNEL);
>> + if (!q->next)
>> + goto err_case;
>> + q->allot = kmalloc(q->depth*sizeof(short), GFP_KERNEL);
>> + if (!q->allot)
>> + goto err_case;
>> + q->hash = kmalloc(q->depth*sizeof(unsigned short), GFP_KERNEL);
>> + if (!q->hash)
>> + goto err_case;
>> + q->qs = kmalloc(q->depth*sizeof(struct sk_buff_head), GFP_KERNEL);
>> + if (!q->qs)
>> + goto err_case;
>
> You may chose to use kcalloc for array allocations.
The arrays in the original code don't get zeroed either, so that
shouldn't be necessary (and I haven't heard of any problems so far). Do
you suggest I use kcalloc() anyway, just as a good practice?
>> for (i=0; i<SFQ_HASH_DIVISOR; i++)
>> - q->ht[i] = SFQ_DEPTH;
>> - for (i=0; i<SFQ_DEPTH; i++) {
>> + q->ht[i] = q->depth;
>> + for (i=0; i<q->depth; i++) {
>> skb_queue_head_init(&q->qs[i]);
>> - q->dep[i+SFQ_DEPTH].next = i+SFQ_DEPTH;
>> - q->dep[i+SFQ_DEPTH].prev = i+SFQ_DEPTH;
>> + q->dep[i+q->depth].next = i+q->depth;
>> + q->dep[i+q->depth].prev = i+q->depth;
>> }
>>
>> - for (i=0; i<SFQ_DEPTH; i++)
>> + for (i=0; i<q->depth; i++)
>> sfq_link(q, i);
>> return 0;
>> +err_case:
>
> This leaks a few kmallocs.
Are you saying that the 'err_case:' leaks kmallocs? It calls
sfq_q_destroy(q), which kfrees each of the arrays: dep, next, allot,
hash, and qs. Is that sufficient, or am I missing something or
misunderstanding you?
>> + sfq_q_destroy(q);
>> + return -ENOBUFS;
>> }
Thank you for your review. Could you please clarify the questions I
have? I'll make, test, and submit a revision of this patch after that.
-Corey
-
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