@linux.intel.com is bouncing my emails again... This happened some
years back as well.
On Thu, Dec 08, 2016 at 02:56:51PM +0300, Dan Carpenter wrote:
> 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
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