reimplement IDR and IDA using the radix tree

Hello Matthew Wilcox,

This is a semi-automatic email about new static checker warnings.

The patch 755edccbffa1: "reimplement IDR and IDA using the radix tree" from Dec 7, 2016, leads to the following Smatch complaint:

lib/radix-tree.c:2380 ida_get_new_above()
warn: variable dereferenced before check 'node' (see line 2355)

lib/radix-tree.c
2354 bit = 0;

  2355		offset = get_slot_offset(node, slot);
                                         ^^^^

Dereferenced inside the function.

2356
2357 bitmap = *slot;
2358 if (bitmap) {
2359 bit = find_next_zero_bit(bitmap->bitmap, IDA_BITMAP_BITS, bit);
2360 index += bit;
2361 if (index > INT_MAX)
2362 return -ENOSPC;
2363 if (bit = IDA_BITMAP_BITS) {
2364 index /= IDA_BITMAP_BITS;
2365 goto restart;
2366 }
2367 __set_bit(bit, bitmap->bitmap);
2368 if (bitmap_full(bitmap->bitmap, IDA_BITMAP_BITS))
2369 node_tag_clear(root, node, IDR_FREE, offset);
2370 bitmap = xchg(&ida->free_bitmap, NULL);
2371 kfree(bitmap);
2372 } else {
2373 index += bit;
2374 bitmap = xchg(&ida->free_bitmap, NULL);
2375 if (!bitmap)
2376 return -EAGAIN;
2377 memset(bitmap, 0, sizeof(*bitmap));
2378 __set_bit(bit, bitmap->bitmap);
2379 rcu_assign_pointer(*slot, bitmap);
2380 if (node)

                            ^^^^

Check too late.

2381 node->count++;
2382 }

regards,
dan carpenter

Hello Matthew Wilcox,

This is a semi-automatic email about new static checker warnings.

The patch 755edccbffa1: "reimplement IDR and IDA using the radix tree" from Dec 7, 2016, leads to the following Smatch complaint:

lib/radix-tree.c:2413 ida_remove()
warn: variable dereferenced before check 'node' (see line 2409)

lib/radix-tree.c
2408 __clear_bit(offset, bitmap->bitmap);

  2409		node_tag_set(&ida->ida_rt, node, IDR_FREE, get_slot_offset(node, slot));
                                                                           ^^^^

Dereference.

2410 if (bitmap_empty(bitmap->bitmap, IDA_BITMAP_BITS)) {
2411 *slot = NULL;
2412 kfree(bitmap);

  2413			if (node) {
                            ^^^^

Check.

  2414				node->count--;
  2415				__radix_tree_delete_node(&ida->ida_rt, node);

regards,
dan carpenter

@linux.intel.com is bouncing my emails again... This happened some years back as well.