linux-user: Don't use CMSG_ALIGN(sizeof struct cmsghdr)

The Linux struct cmsghdr is already guaranteed to be sufficiently
aligned that CMSG_ALIGN(sizeof struct cmsghdr) is always equal
to sizeof struct cmsghdr. Stop doing the unnecessary alignment
arithmetic for host and target cmsghdr.

This follows kernel commit 1ff8cebf49ed9e9ca2 and brings our
TARGET_CMSG_* macros back into line with the kernel ones,
as well as making them easier to understand.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <1513345976-22958-3-git-send-email-peter.maydell@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

1 files changed, 2 insertions, 2 deletions

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index a1b9772a85..39553c81b6 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -1692,7 +1692,7 @@ static inline abi_long target_to_host_cmsg(struct msghdr *msgh,
         void *target_data = TARGET_CMSG_DATA(target_cmsg);
 
         int len = tswapal(target_cmsg->cmsg_len)
-                  - TARGET_CMSG_ALIGN(sizeof (struct target_cmsghdr));
+            - sizeof(struct target_cmsghdr);
 
         space += CMSG_SPACE(len);
         if (space > msgh->msg_controllen) {
@@ -1773,7 +1773,7 @@ static inline abi_long host_to_target_cmsg(struct target_msghdr *target_msgh,
         void *data = CMSG_DATA(cmsg);
         void *target_data = TARGET_CMSG_DATA(target_cmsg);
 
-        int len = cmsg->cmsg_len - CMSG_ALIGN(sizeof (struct cmsghdr));
+        int len = cmsg->cmsg_len - sizeof(struct cmsghdr);
         int tgt_len, tgt_space;
 
         /* We never copy a half-header but may copy half-data;