aboutsummaryrefslogtreecommitdiff
path: root/migration
diff options
context:
space:
mode:
authorWei Yang <richardw.yang@linux.intel.com>2019-09-11 13:28:39 +0000
committerDr. David Alan Gilbert <dgilbert@redhat.com>2019-09-12 11:23:32 +0100
commit1bf57fb3df9615b50219c50b381cc52e303f682c (patch)
treeac3d66c60d945acf42e15580f70fdcae5f750b2d /migration
parent89fe04b4585c97fda7c173bee97bbacb32f64e80 (diff)
migration/qemu-file: fix potential buf waste for extra buf_index adjustment
In add_to_iovec(), qemu_fflush() will be called if iovec is full. If this happens, buf_index is reset. Currently, this is not checked and buf_index would always been adjust with buf size. This is not harmful, but will waste some space in file buffer. This patch make add_to_iovec() return 1 when it has flushed the file. Then the caller could check the return value to see whether it is necessary to adjust the buf_index any more. Signed-off-by: Wei Yang <richardw.yang@linux.intel.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Message-Id: <20190911132839.23336-3-richard.weiyang@gmail.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Diffstat (limited to 'migration')
-rw-r--r--migration/qemu-file.c43
1 files changed, 26 insertions, 17 deletions
diff --git a/migration/qemu-file.c b/migration/qemu-file.c
index 66627088d4..26fb25ddc1 100644
--- a/migration/qemu-file.c
+++ b/migration/qemu-file.c
@@ -381,8 +381,16 @@ int qemu_fclose(QEMUFile *f)
return ret;
}
-static void add_to_iovec(QEMUFile *f, const uint8_t *buf, size_t size,
- bool may_free)
+/*
+ * Add buf to iovec. Do flush if iovec is full.
+ *
+ * Return values:
+ * 1 iovec is full and flushed
+ * 0 iovec is not flushed
+ *
+ */
+static int add_to_iovec(QEMUFile *f, const uint8_t *buf, size_t size,
+ bool may_free)
{
/* check for adjacent buffer and coalesce them */
if (f->iovcnt > 0 && buf == f->iov[f->iovcnt - 1].iov_base +
@@ -400,6 +408,19 @@ static void add_to_iovec(QEMUFile *f, const uint8_t *buf, size_t size,
if (f->iovcnt >= MAX_IOV_SIZE) {
qemu_fflush(f);
+ return 1;
+ }
+
+ return 0;
+}
+
+static void add_buf_to_iovec(QEMUFile *f, size_t len)
+{
+ if (!add_to_iovec(f, f->buf + f->buf_index, len, false)) {
+ f->buf_index += len;
+ if (f->buf_index == IO_BUF_SIZE) {
+ qemu_fflush(f);
+ }
}
}
@@ -429,11 +450,7 @@ void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, size_t size)
}
memcpy(f->buf + f->buf_index, buf, l);
f->bytes_xfer += l;
- add_to_iovec(f, f->buf + f->buf_index, l, false);
- f->buf_index += l;
- if (f->buf_index == IO_BUF_SIZE) {
- qemu_fflush(f);
- }
+ add_buf_to_iovec(f, l);
if (qemu_file_get_error(f)) {
break;
}
@@ -450,11 +467,7 @@ void qemu_put_byte(QEMUFile *f, int v)
f->buf[f->buf_index] = v;
f->bytes_xfer++;
- add_to_iovec(f, f->buf + f->buf_index, 1, false);
- f->buf_index++;
- if (f->buf_index == IO_BUF_SIZE) {
- qemu_fflush(f);
- }
+ add_buf_to_iovec(f, 1);
}
void qemu_file_skip(QEMUFile *f, int size)
@@ -760,11 +773,7 @@ ssize_t qemu_put_compression_data(QEMUFile *f, z_stream *stream,
}
qemu_put_be32(f, blen);
- add_to_iovec(f, f->buf + f->buf_index, blen, false);
- f->buf_index += blen;
- if (f->buf_index == IO_BUF_SIZE) {
- qemu_fflush(f);
- }
+ add_buf_to_iovec(f, blen);
return blen + sizeof(int32_t);
}