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| author | Eric Dumazet <edumazet@google.com> | 2021-04-15 10:37:53 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-04-15 17:03:33 -0700 |
| commit | 38ebcf5096a86762b82262e96b2c8b170fe79040 (patch) | |
| tree | e374d75ffd37f3053bf687938f8596aea6988f69 /net/core | |
| parent | b6faf160d0dac3c8654aa911e6e281541628d304 (diff) | |
| download | linux-38ebcf5096a86762b82262e96b2c8b170fe79040.tar.gz linux-38ebcf5096a86762b82262e96b2c8b170fe79040.tar.bz2 linux-38ebcf5096a86762b82262e96b2c8b170fe79040.zip | |
scm: optimize put_cmsg()
Calling two copy_to_user() for very small regions has very high overhead.
Switch to inlined unsafe_put_user() to save one stac/clac sequence,
and avoid copy_to_user().
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/scm.c | 23 |
1 files changed, 15 insertions, 8 deletions
diff --git a/net/core/scm.c b/net/core/scm.c index 8156d4fb8a39..bd96c922041d 100644 --- a/net/core/scm.c +++ b/net/core/scm.c @@ -228,14 +228,16 @@ int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data) if (msg->msg_control_is_user) { struct cmsghdr __user *cm = msg->msg_control_user; - struct cmsghdr cmhdr; - - cmhdr.cmsg_level = level; - cmhdr.cmsg_type = type; - cmhdr.cmsg_len = cmlen; - if (copy_to_user(cm, &cmhdr, sizeof cmhdr) || - copy_to_user(CMSG_USER_DATA(cm), data, cmlen - sizeof(*cm))) - return -EFAULT; + + if (!user_write_access_begin(cm, cmlen)) + goto efault; + + unsafe_put_user(len, &cm->cmsg_len, efault_end); + unsafe_put_user(level, &cm->cmsg_level, efault_end); + unsafe_put_user(type, &cm->cmsg_type, efault_end); + unsafe_copy_to_user(CMSG_USER_DATA(cm), data, + cmlen - sizeof(*cm), efault_end); + user_write_access_end(); } else { struct cmsghdr *cm = msg->msg_control; @@ -249,6 +251,11 @@ int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data) msg->msg_control += cmlen; msg->msg_controllen -= cmlen; return 0; + +efault_end: + user_write_access_end(); +efault: + return -EFAULT; } EXPORT_SYMBOL(put_cmsg); |