Re: [PATCH v4 net-next 8/9] net: add a hardware buffer management helper API

Hi Marcin,
 
 On dim., mars 06 2016, Marcin Wojtas [off-list ref] wrote:

Hi Gregory,

quoted

+int hwbm_pool_add(struct hwbm_pool *bm_pool, unsigned int buf_num, gfp_t gfp)
+{
+       int err, i;
+       unsigned long flags;
+
+       spin_lock_irqsave(&bm_pool->lock, flags);
+       if (bm_pool->buf_num == bm_pool->size) {

'size' field is used as a 'frag_size' but here it means pool capacity.
I think it's better to keep 'size' for pool capacity and add
'buf_size' field to struct hwbm_pool.

I thought I already added this field, but it seems that I didn't so. So
I will add it.

quoted

+               pr_warn("pool already filled\n");
+               return bm_pool->buf_num;
+       }
+
+       if (buf_num + bm_pool->buf_num > bm_pool->size) {
+               pr_warn("cannot allocate %d buffers for pool\n",
+                       buf_num);
+               return 0;
+       }
+
+       if ((buf_num + bm_pool->buf_num) < bm_pool->buf_num) {

What is a point of this condition? How possibly after checking if
capacity of pool is not exceeded, this one would ever be true?

see http://thread.gmane.org/gmane.linux.kernel/2125152/focus=2137421

this test is here to ensure that (buf_num + bm_pool->buf_nu doesn't
wrap.

Thanks,

Gregory

-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com