On Fri, 10 Dec 2010 15:31:26 +0800
shaohui.zheng@xxxxxxxxx wrote:
> From: Shaohui Zheng <shaohui.zheng@xxxxxxxxx>
>
> Add add_memory interface to support to memory hotplug emulation for each online
> node under debugfs. The reserved memory can be added into desired node with
> this interface.
>
> The layout on debugfs:
> mem_hotplug/node0/add_memory
> mem_hotplug/node1/add_memory
> mem_hotplug/node2/add_memory
> ...
>
> Add a memory section(128M) to node 3(boots with mem=1024m)
>
> echo 0x40000000 > mem_hotplug/node3/add_memory
>
>
> ...
>
> +#ifdef CONFIG_ARCH_MEMORY_PROBE
> +
> +static ssize_t add_memory_store(struct file *file, const char __user *buf,
> + size_t count, loff_t *ppos)
> +{
> + u64 phys_addr = 0;
Even more unneeded initalisation.
Please check the whole patchset for this. It's bad because it can
sometimes generate more code and because it can sometimes hide bugs by
suppressing used-uninitialsied warnings.
> + int nid = file->private_data - NULL;
Well that was sneaky.
It would be more conventional to just use the typecast:
int nid = (long)file->private_data;
> + int ret;
> +
> + printk(KERN_INFO "Add a memory section to node: %d.\n", nid);
> + phys_addr = simple_strtoull(buf, NULL, 0);
checkpatch
> + ret = add_memory(nid, phys_addr, PAGES_PER_SECTION << PAGE_SHIFT);
> + if (ret)
> + count = ret;
> +
> + return count;
> +}
> +
> +static int add_memory_open(struct inode *inode, struct file *file)
> +{
> + file->private_data = inode->i_private;
Was this usage of i_private and private_data documented in comments
somewhere?
> + return 0;
> +}
> +
> +static const struct file_operations add_memory_file_ops = {
> + .open = add_memory_open,
> + .write = add_memory_store,
> + .llseek = generic_file_llseek,
> +};
> +
> +/*
> + * Create add_memory debugfs entry under specified node
> + */
> +static int debugfs_create_add_memory_entry(int nid)
> +{
> + char buf[32];
> + static struct dentry *node_debug_root;
> +
> + snprintf(buf, sizeof(buf), "node%d", nid);
> + node_debug_root = debugfs_create_dir(buf, memhp_debug_root);
> + if (!node_debug_root)
> + return -ENOMEM;
hm, debugfs_create_dir() was poorly designed - it should return an
ERR_PTR() so callers don't need to assume ENOMEM, which may be incorrect.
> + /* the nid information was represented by the offset of pointer(NULL+nid) */
> + if (!debugfs_create_file("add_memory", S_IWUSR, node_debug_root,
> + NULL + nid, &add_memory_file_ops))
> + return -ENOMEM;
> +
> + return 0;
> +}
> +
> +static int __init memory_debug_init(void)
> +{
> + int nid;
> +
> + if (!memhp_debug_root)
> + memhp_debug_root = debugfs_create_dir("mem_hotplug", NULL);
> + if (!memhp_debug_root)
> + return -ENOMEM;
> +
> + for_each_online_node(nid)
> + debugfs_create_add_memory_entry(nid);
> +
> + return 0;
> +}
> +
> +module_init(memory_debug_init);
> +#else
> +static debugfs_create_add_memory_entry(int nid)
"static int".
> +{
> + return 0;
> +}
> +#endif /* CONFIG_ARCH_MEMORY_PROBE */
> +
> static ssize_t add_node_store(struct file *file, const char __user *buf,
> size_t count, loff_t *ppos)
> {
> @@ -963,6 +1038,8 @@
> return -ENOMEM;
>
> ret = add_memory(nid, start, size);
> +
> + debugfs_create_add_memory_entry(nid);
> return ret ? ret : count;
> }
>
>
> ...
>
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