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authorPaolo Bonzini <pbonzini@redhat.com>2011-09-08 13:46:25 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2011-12-22 11:53:53 +0100
commit8c5135f90e2dcf1d5c3d03106e0ac6e371ccb572 (patch)
tree5c5976aeb886b20ea1f564cc828b448e56fcbebd /cutils.c
parent993295fedc5fefaefee9ac80e057d8bf08026ef4 (diff)
sheepdog: move coroutine send/recv function to generic code
Outside coroutines, avoid busy waiting on EAGAIN by temporarily making the socket blocking. The API of qemu_recvv/qemu_sendv is slightly different from do_readv/do_writev because they do not handle coroutines. It returns the number of bytes written before encountering an EAGAIN. The specificity of yielding on EAGAIN is entirely in qemu-coroutine.c. Reviewed-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'cutils.c')
-rw-r--r--cutils.c111
1 files changed, 111 insertions, 0 deletions
diff --git a/cutils.c b/cutils.c
index 24b3fe355b..a6ffd46445 100644
--- a/cutils.c
+++ b/cutils.c
@@ -25,6 +25,8 @@
#include "host-utils.h"
#include <math.h>
+#include "qemu_socket.h"
+
void pstrcpy(char *buf, int buf_size, const char *str)
{
int c;
@@ -403,3 +405,112 @@ int qemu_parse_fd(const char *param)
}
return fd;
}
+
+/*
+ * Send/recv data with iovec buffers
+ *
+ * This function send/recv data from/to the iovec buffer directly.
+ * The first `offset' bytes in the iovec buffer are skipped and next
+ * `len' bytes are used.
+ *
+ * For example,
+ *
+ * do_sendv_recvv(sockfd, iov, len, offset, 1);
+ *
+ * is equal to
+ *
+ * char *buf = malloc(size);
+ * iov_to_buf(iov, iovcnt, buf, offset, size);
+ * send(sockfd, buf, size, 0);
+ * free(buf);
+ */
+static int do_sendv_recvv(int sockfd, struct iovec *iov, int len, int offset,
+ int do_sendv)
+{
+ int ret, diff, iovlen;
+ struct iovec *last_iov;
+
+ /* last_iov is inclusive, so count from one. */
+ iovlen = 1;
+ last_iov = iov;
+ len += offset;
+
+ while (last_iov->iov_len < len) {
+ len -= last_iov->iov_len;
+
+ last_iov++;
+ iovlen++;
+ }
+
+ diff = last_iov->iov_len - len;
+ last_iov->iov_len -= diff;
+
+ while (iov->iov_len <= offset) {
+ offset -= iov->iov_len;
+
+ iov++;
+ iovlen--;
+ }
+
+ iov->iov_base = (char *) iov->iov_base + offset;
+ iov->iov_len -= offset;
+
+ {
+#if defined CONFIG_IOVEC && defined CONFIG_POSIX
+ struct msghdr msg;
+ memset(&msg, 0, sizeof(msg));
+ msg.msg_iov = iov;
+ msg.msg_iovlen = iovlen;
+
+ do {
+ if (do_sendv) {
+ ret = sendmsg(sockfd, &msg, 0);
+ } else {
+ ret = recvmsg(sockfd, &msg, 0);
+ }
+ } while (ret == -1 && errno == EINTR);
+#else
+ struct iovec *p = iov;
+ ret = 0;
+ while (iovlen > 0) {
+ int rc;
+ if (do_sendv) {
+ rc = send(sockfd, p->iov_base, p->iov_len, 0);
+ } else {
+ rc = qemu_recv(sockfd, p->iov_base, p->iov_len, 0);
+ }
+ if (rc == -1) {
+ if (errno == EINTR) {
+ continue;
+ }
+ if (ret == 0) {
+ ret = -1;
+ }
+ break;
+ }
+ if (rc == 0) {
+ break;
+ }
+ ret += rc;
+ iovlen--, p++;
+ }
+#endif
+ }
+
+ /* Undo the changes above */
+ iov->iov_base = (char *) iov->iov_base - offset;
+ iov->iov_len += offset;
+ last_iov->iov_len += diff;
+ return ret;
+}
+
+int qemu_recvv(int sockfd, struct iovec *iov, int len, int iov_offset)
+{
+ return do_sendv_recvv(sockfd, iov, len, iov_offset, 0);
+}
+
+int qemu_sendv(int sockfd, struct iovec *iov, int len, int iov_offset)
+{
+ return do_sendv_recvv(sockfd, iov, len, iov_offset, 1);
+}
+