From a9a0c51af4e7c825c014b40694571456a75ebbc4 Mon Sep 17 00:00:00 2001 From: Alex Elder Date: Wed, 15 Feb 2012 07:43:54 -0600 Subject: libceph: separate CRC calculation from byte swapping Calculate CRC in a separate step from rearranging the byte order of the result, to improve clarity and readability. Use offsetof() to determine the number of bytes to include in the CRC calculation. In read_partial_message(), switch which value gets byte-swapped, since the just-computed CRC is already likely to be in a register. Signed-off-by: Alex Elder Signed-off-by: Sage Weil --- net/ceph/messenger.c | 31 +++++++++++++++++-------------- 1 file changed, 17 insertions(+), 14 deletions(-) (limited to 'net') diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c index 204e229e6628..7ec6a228b667 100644 --- a/net/ceph/messenger.c +++ b/net/ceph/messenger.c @@ -521,6 +521,7 @@ static void prepare_write_message_footer(struct ceph_connection *con) static void prepare_write_message(struct ceph_connection *con) { struct ceph_msg *m; + u32 crc; ceph_con_out_kvec_reset(con); con->out_kvec_is_msg = true; @@ -569,17 +570,17 @@ static void prepare_write_message(struct ceph_connection *con) m->middle->vec.iov_base); /* fill in crc (except data pages), footer */ - con->out_msg->hdr.crc = - cpu_to_le32(crc32c(0, &m->hdr, - sizeof(m->hdr) - sizeof(m->hdr.crc))); + crc = crc32c(0, &m->hdr, offsetof(struct ceph_msg_header, crc)); + con->out_msg->hdr.crc = cpu_to_le32(crc); con->out_msg->footer.flags = CEPH_MSG_FOOTER_COMPLETE; - con->out_msg->footer.front_crc = - cpu_to_le32(crc32c(0, m->front.iov_base, m->front.iov_len)); - if (m->middle) - con->out_msg->footer.middle_crc = - cpu_to_le32(crc32c(0, m->middle->vec.iov_base, - m->middle->vec.iov_len)); - else + + crc = crc32c(0, m->front.iov_base, m->front.iov_len); + con->out_msg->footer.front_crc = cpu_to_le32(crc); + if (m->middle) { + crc = crc32c(0, m->middle->vec.iov_base, + m->middle->vec.iov_len); + con->out_msg->footer.middle_crc = cpu_to_le32(crc); + } else con->out_msg->footer.middle_crc = 0; con->out_msg->footer.data_crc = 0; dout("prepare_write_message front_crc %u data_crc %u\n", @@ -875,12 +876,13 @@ static int write_partial_msg_pages(struct ceph_connection *con) total_max_write); if (do_crc && !con->out_msg_pos.did_page_crc) { + u32 crc; void *base = kaddr + con->out_msg_pos.page_pos; u32 tmpcrc = le32_to_cpu(con->out_msg->footer.data_crc); BUG_ON(kaddr == NULL); - con->out_msg->footer.data_crc = - cpu_to_le32(crc32c(tmpcrc, base, len)); + crc = crc32c(tmpcrc, base, len); + con->out_msg->footer.data_crc = cpu_to_le32(crc); con->out_msg_pos.did_page_crc = true; } ret = kernel_sendpage(con->sock, page, @@ -1650,8 +1652,9 @@ static int read_partial_message(struct ceph_connection *con) con->in_base_pos += ret; if (con->in_base_pos == sizeof(con->in_hdr)) { u32 crc = crc32c(0, &con->in_hdr, - sizeof(con->in_hdr) - sizeof(con->in_hdr.crc)); - if (crc != le32_to_cpu(con->in_hdr.crc)) { + offsetof(struct ceph_msg_header, crc)); + + if (cpu_to_le32(crc) != con->in_hdr.crc) { pr_err("read_partial_message bad hdr " " crc %u != expected %u\n", crc, con->in_hdr.crc); -- cgit v1.2.3-59-g8ed1b