Remove redundant (base_addr >= pool->addrs_cnt) comparison from the
conditional.
In particular, addr is computed as:
addr = base_addr + offset
where base_addr and offset are stored as 48-bit and 16-bit unsigned
integers, respectively. The above sum cannot overflow u64 since
base_addr has a maximum value of 0x0000ffffffffffff and offset has a
maximum value of 0xffff (implying a maximum sum of 0x000100000000fffe).
Since overflow is impossible, it follows that addr >= base_addr.
Now if (base_addr >= pool->addrs_cnt), then clearly:
addr >= base_addr
>= pool->addrs_cnt
Thus, (base_addr >= pool->addrs_cnt) implies (addr >= pool->addrs_cnt).
Subsequently, the former comparison is unnecessary in the conditional
since for any boolean expressions A and B, (A || B) && (A -> B) is
equivalent to B.
Signed-off-by: Kal Conley <[email protected]>
---
net/xdp/xsk_queue.h | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/net/xdp/xsk_queue.h b/net/xdp/xsk_queue.h
index 66c6f57c9c44..016f3753180a 100644
--- a/net/xdp/xsk_queue.h
+++ b/net/xdp/xsk_queue.h
@@ -153,16 +153,14 @@ static inline bool xp_aligned_validate_desc(struct xsk_buff_pool *pool,
static inline bool xp_unaligned_validate_desc(struct xsk_buff_pool *pool,
struct xdp_desc *desc)
{
- u64 addr, base_addr;
-
- base_addr = xp_unaligned_extract_addr(desc->addr);
- addr = xp_unaligned_add_offset_to_addr(desc->addr);
+ u64 addr;
if (desc->len > pool->chunk_size)
return false;
- if (base_addr >= pool->addrs_cnt || addr >= pool->addrs_cnt ||
- addr + desc->len > pool->addrs_cnt ||
+ addr = xp_unaligned_add_offset_to_addr(desc->addr);
+
+ if (addr >= pool->addrs_cnt || addr + desc->len > pool->addrs_cnt ||
xp_desc_crosses_non_contig_pg(pool, addr, desc->len))
return false;
--
2.39.2
> + addr = xp_unaligned_add_offset_to_addr(desc->addr);
> +
I guess this assignment should simply be combined with the variable
declaration. This will shorten the function by an additional two lines
of code.