From 11e29054fe91ceaf59d2a500e09c4da262c7b23e Mon Sep 17 00:00:00 2001 From: David Gibson Date: Fri, 6 Sep 2024 21:49:37 +1000 Subject: [PATCH] tap: Improve handling of EINTR in tap_passt_input() When tap_passt_input() gets an error from recv() it (correctly) does not print any error message for EINTR, EAGAIN or EWOULDBLOCK. However in all three cases it returns from the function. That makes sense for EAGAIN and EWOULDBLOCK, since we then want to wait for the next EPOLLIN event before trying again. For EINTR, however, it makes more sense to retry immediately - as it stands we're likely to get a renewer EPOLLIN event immediately in that case, since we're using level triggered signalling. So, handle EINTR separately by immediately retrying until we succeed or get a different type of error. Signed-off-by: David Gibson Signed-off-by: Stefano Brivio --- tap.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/tap.c b/tap.c index c8abc06..8977b3f 100644 --- a/tap.c +++ b/tap.c @@ -1003,10 +1003,13 @@ static void tap_passt_input(struct ctx *c, const struct timespec *now) memmove(pkt_buf, partial_frame, partial_len); } - n = recv(c->fd_tap, pkt_buf + partial_len, TAP_BUF_BYTES - partial_len, - MSG_DONTWAIT); + do { + n = recv(c->fd_tap, pkt_buf + partial_len, + TAP_BUF_BYTES - partial_len, MSG_DONTWAIT); + } while ((n < 0) && errno == EINTR); + if (n < 0) { - if (errno != EINTR && errno != EAGAIN && errno != EWOULDBLOCK) { + if (errno != EAGAIN && errno != EWOULDBLOCK) { err_perror("Receive error on guest connection, reset"); tap_sock_reset(c); }