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[v2,net-next,0/2] net: socket: use BIT() for MSG_* and fix MSG_CMSG_COMPAT

Message ID 20210321134357.148323-1-dong.menglong@zte.com.cn
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Series net: socket: use BIT() for MSG_* and fix MSG_CMSG_COMPAT | expand

Message

Menglong Dong March 21, 2021, 1:43 p.m. UTC 
From: Menglong Dong <dong.menglong@zte.com.cn>

In the first patch, I use BIT() for MSG_* to make the code tidier.

Directly use BIT() for MSG_* will be a bit problematic, because
'msg_flags' is defined as 'int' somewhere, and MSG_CMSG_COMPAT
will make it become negative, just like what Guenter Roeck
reported here:

https://lore.kernel.org/netdev/20210317013758.GA134033@roeck-us.net

So in the second patch, I change MSG_CMSG_COMPAT to BIT(21), as
David Laight suggested. MSG_CMSG_COMPAT is an internal value,
which is't used in userspace, so this change works.

In version 2, some comment is added in patch 2 to stop people
from using BIT(31) for MSG_* in the feature, as Herbert Xu
suggested.


Menglong Dong (2):
  net: socket: use BIT() for MSG_*
  net: socket: change MSG_CMSG_COMPAT to BIT(21)

 include/linux/socket.h | 75 +++++++++++++++++++++++-------------------
 1 file changed, 41 insertions(+), 34 deletions(-)