Mercurial > dropbear
changeset 1075:cc6116cc0b5c
Avoid channel writev() when there is nothing to write
| author | Matt Johnston <matt@ucc.asn.au> |
|---|---|
| date | Sat, 21 Mar 2015 22:43:08 +0800 |
| parents | 10f198d4a308 |
| children | d92597ef089e |
| files | common-channel.c |
| diffstat | 1 files changed, 10 insertions(+), 1 deletions(-) [+] |
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--- a/common-channel.c Fri Mar 20 23:36:42 2015 +0800 +++ b/common-channel.c Sat Mar 21 22:43:08 2015 +0800 @@ -473,6 +473,14 @@ io_count++; } + if (io_count == 0) { + /* writechannel may sometimes be called twice in a main loop iteration. + From common_recv_msg_channel_data() then channelio(). + The second call may not have any data to write, so we just return. */ + TRACE(("leave writechannel, no data")) + return; + } + if (morelen) { /* Default return value, none consumed */ *morelen = 0; @@ -482,7 +490,7 @@ if (written < 0) { if (errno != EINTR && errno != EAGAIN) { - TRACE(("errno %d", errno)) + TRACE(("channel IO write error fd %d %s", fd, strerror(errno))) close_chan_fd(channel, fd, SHUT_WR); } } else { @@ -830,6 +838,7 @@ channel->recvwindow -= datalen; dropbear_assert(channel->recvwindow <= opts.recv_window); + /* Attempt to write the data immediately without having to put it in the circular buffer */ consumed = datalen; writechannel(channel, fd, cbuf, buf_getptr(ses.payload, datalen), &consumed);