[SOCK] Avoid divides in sk_stream_pages() and __sk_stream_mem_reclaim()

sk_forward_alloc being signed, we should take care of divides by
SK_STREAM_MEM_QUANTUM we do in sk_stream_pages() and
__sk_stream_mem_reclaim()

This patchs introduces SK_STREAM_MEM_QUANTUM_SHIFT, defined
as ilog2(SK_STREAM_MEM_QUANTUM), to be able to use right
shifts instead of plain divides.

This should help compiler to choose right shifts instead of
expensive divides (as seen with CONFIG_CC_OPTIMIZE_FOR_SIZE=y on x86)

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/core/stream.c b/net/core/stream.c
index 5586879bb9b3..bf188ffdbdbe 100644
--- a/net/core/stream.c
+++ b/net/core/stream.c
@@ -196,7 +196,7 @@ EXPORT_SYMBOL(sk_stream_error);
 
 void __sk_stream_mem_reclaim(struct sock *sk)
 {
-        atomic_sub(sk->sk_forward_alloc / SK_STREAM_MEM_QUANTUM,
+        atomic_sub(sk->sk_forward_alloc >> SK_STREAM_MEM_QUANTUM_SHIFT,
                    sk->sk_prot->memory_allocated);
         sk->sk_forward_alloc &= SK_STREAM_MEM_QUANTUM - 1;
         if (*sk->sk_prot->memory_pressure &&