Add a generic iov_truncate() function that truncates an IO vector to a given number of bytes, returning the number of iov entries that contain data after truncation. Use it in udp_vu_sock_recv() to replace the open-coded truncation logic that adjusted iov entries after recvmsg(). Signed-off-by: Laurent Vivier --- iov.c | 22 ++++++++++++++++++++++ iov.h | 1 + udp_vu.c | 12 +++--------- 3 files changed, 26 insertions(+), 9 deletions(-) diff --git a/iov.c b/iov.c index ad726daa4cd8..31a3f5bc29e5 100644 --- a/iov.c +++ b/iov.c @@ -147,6 +147,28 @@ size_t iov_size(const struct iovec *iov, size_t iov_cnt) return len; } +/** + * iov_truncate() - Truncate an IO vector to a given number of bytes + * @iov: IO vector (modified) + * @iov_cnt: Number of entries in @iov + * @size: Total number of bytes to keep + * + * Return: number of iov entries that contain data after truncation + */ +size_t iov_truncate(struct iovec *iov, size_t iov_cnt, size_t size) +{ + size_t i, offset; + + i = iov_skip_bytes(iov, iov_cnt, size, &offset); + + if (i < iov_cnt) { + iov[i].iov_len = offset; + i += !!offset; + } + + return i; +} + /** * iov_tail_prune() - Remove any unneeded buffers from an IOV tail * @tail: IO vector tail (modified) diff --git a/iov.h b/iov.h index d2184bfd12bd..f87436f5479b 100644 --- a/iov.h +++ b/iov.h @@ -28,6 +28,7 @@ size_t iov_from_buf(const struct iovec *iov, size_t iov_cnt, size_t iov_to_buf(const struct iovec *iov, size_t iov_cnt, size_t offset, void *buf, size_t bytes); size_t iov_size(const struct iovec *iov, size_t iov_cnt); +size_t iov_truncate(struct iovec *iov, size_t iov_cnt, size_t size); /* * DOC: Theory of Operation, struct iov_tail diff --git a/udp_vu.c b/udp_vu.c index 51f3718f5925..3f558a33b4f2 100644 --- a/udp_vu.c +++ b/udp_vu.c @@ -71,9 +71,9 @@ static int udp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq, int s, bool v6, ssize_t *dlen) { const struct vu_dev *vdev = c->vdev; - int iov_cnt, idx, iov_used; - size_t off, hdrlen, l2len; struct msghdr msg = { 0 }; + int iov_cnt, iov_used; + size_t hdrlen, l2len; ASSERT(!c->no_udp); @@ -115,13 +115,7 @@ static int udp_vu_sock_recv(const struct ctx *c, struct vu_virtq *vq, int s, iov_vu[0].iov_base = (char *)iov_vu[0].iov_base - hdrlen; iov_vu[0].iov_len += hdrlen; - /* count the numbers of buffer filled by recvmsg() */ - idx = iov_skip_bytes(iov_vu, iov_cnt, *dlen + hdrlen, &off); - - /* adjust last iov length */ - if (idx < iov_cnt) - iov_vu[idx].iov_len = off; - iov_used = idx + !!off; + iov_used = iov_truncate(iov_vu, iov_cnt, *dlen + hdrlen); /* pad frame to 60 bytes: first buffer is at least ETH_ZLEN long */ l2len = *dlen + hdrlen - VNET_HLEN; -- 2.53.0