net: revert "net: get rid of an signed integer overflow in ip_idents_reserve()"

Commit adb03115f459 ("net: get rid of an signed integer overflow in ip_idents_reserve()")
used atomic_cmpxchg to replace "atomic_add_return" inside the function
"ip_idents_reserve". The reason was to avoid UBSAN warning.
However, this change has caused performance degrade and in GCC-8,
fno-strict-overflow is now mapped to -fwrapv -fwrapv-pointer
and signed integer overflow is now undefined by default at all
optimization levels[1]. Moreover, it was a bug in UBSAN vs -fwrapv
/-fno-strict-overflow, so Let's revert it safely.

[1] https://gcc.gnu.org/gcc-8/changes.html

Suggested-by: Peter Zijlstra <[email protected]>
Suggested-by: Eric Dumazet <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Alexey Kuznetsov <[email protected]>
Cc: Hideaki YOSHIFUJI <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Jiri Pirko <[email protected]>
Cc: Arvind Sankar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Jiong Wang <[email protected]>
Signed-off-by: Yuqi Jin <[email protected]>
Signed-off-by: Shaokun Zhang <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

0 files changed, 0 insertions, 0 deletions