Subject: Re: [Suggestion] net/core: cpumask_scnprintf, use (PAGE_SIZE - 1) instead of PAGE_SIZE

From: Chen Gang <[email-masked]>
Date: Wed, 21 Nov 2012 16:02:00 +0800

Hi David

 also for show_xps_map in net/core/net-sysfs.c

Regard

gchen

 933 static ssize_t show_xps_map(struct netdev_queue *queue,
 934                             struct netdev_queue_attribute *attribute, char *buf)
 935 {
 936         struct net_device *dev = queue->dev;
 937         struct xps_dev_maps *dev_maps;
 938         cpumask_var_t mask;
 939         unsigned long index;
 940         size_t len = 0;
 941         int i;
 942 
 943         if (!zalloc_cpumask_var(&mask, GFP_KERNEL))
 944                 return -ENOMEM;
 945 
 946         index = get_netdev_queue_index(queue);
 947 
 948         rcu_read_lock();
 949         dev_maps = rcu_dereference(dev->xps_maps);
 950         if (dev_maps) {
 951                 for_each_possible_cpu(i) {
 952                         struct xps_map *map =
 953                             rcu_dereference(dev_maps->cpu_map[i]);
 954                         if (map) {
 955                                 int j;
 956                                 for (j = 0; j < map->len; j++) {
 957                                         if (map->queues[j] == index) {
 958                                                 cpumask_set_cpu(i, mask);
 959                                                 break;
 960                                         }
 961                                 }
 962                         }
 963                 }
 964         }
 965         rcu_read_unlock();
 966 
 967         len += cpumask_scnprintf(buf + len, PAGE_SIZE, mask);
 968         if (PAGE_SIZE - len < 3) {
 969                 free_cpumask_var(mask);
 970                 return -EINVAL;
 971         }
 972 
 973         free_cpumask_var(mask);
 974         len += sprintf(buf + len, "\n");
 975         return len;
 976 }

于 2012年11月21日 15:55, Chen Gang 写道:
> Hi David Miller:
> 
> in net/core/net-sysfs.c:
> 
>   at line 496, we need use (PAGE_SIZE -1) instead of PAGE_SIZE.
>   since at line 505, we append '\n'.
> 
>   regard
> 
> gchen
> 
> 
>  479 static ssize_t show_rps_map(struct netdev_rx_queue *queue,
>  480                             struct rx_queue_attribute *attribute, char *buf)
>  481 {
>  482         struct rps_map *map;
>  483         cpumask_var_t mask;
>  484         size_t len = 0;
>  485         int i;
>  486 
>  487         if (!zalloc_cpumask_var(&mask, GFP_KERNEL))
>  488                 return -ENOMEM;
>  489 
>  490         rcu_read_lock();
>  491         map = rcu_dereference(queue->rps_map);
>  492         if (map)
>  493                 for (i = 0; i < map->len; i++)
>  494                         cpumask_set_cpu(map->cpus[i], mask);
>  495 
>  496         len += cpumask_scnprintf(buf + len, PAGE_SIZE, mask);
>  497         if (PAGE_SIZE - len < 3) {
>  498                 rcu_read_unlock();
>  499                 free_cpumask_var(mask);
>  500                 return -EINVAL;
>  501         }
>  502         rcu_read_unlock();
>  503 
>  504         free_cpumask_var(mask);
>  505         len += sprintf(buf + len, "\n");
>  506         return len;
>  507 }
>  508 
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-- 
Chen Gang

Asianux Corporation