Use poll(2) to wait for a message. If a client/server cannot send a message for any reasons, the current server/client will wait in a blocking read operation. So, we use poll(2) for avoiding remaining in a blocking state.
Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae...@hitachi.com> --- trace-msg.c | 42 ++++++++++++++++++++++++++++++++++++------ 1 file changed, 36 insertions(+), 6 deletions(-) diff --git a/trace-msg.c b/trace-msg.c index cf82ff6..61bde54 100644 --- a/trace-msg.c +++ b/trace-msg.c @@ -396,6 +396,27 @@ error: return -ENOMSG; } +#define MSG_WAIT_MSEC 5000 + +/* + * A return value of 0 indicates time-out + */ +static int tracecmd_msg_recv_wait(int fd, char *buf, struct tracecmd_msg **msg) +{ + struct pollfd pfd; + int ret; + + pfd.fd = fd; + pfd.events = POLLIN; + ret = poll(&pfd, 1, MSG_WAIT_MSEC); + if (ret < 0) { + return -errno; + } else if (ret == 0) + return -ETIMEDOUT; + + return tracecmd_msg_recv(fd, buf); +} + static void *tracecmd_msg_buf_access(struct tracecmd_msg *msg, int offset) { return (void *)msg + offset; @@ -407,9 +428,12 @@ static int tracecmd_msg_wait_for_msg(int fd, struct tracecmd_msg **msg) u32 cmd; int ret; - ret = tracecmd_msg_recv(fd, msg_tmp); - if (ret < 0) + ret = tracecmd_msg_recv_wait(fd, msg_tmp, msg); + if (ret < 0) { + if (ret == -ETIMEDOUT) + warning("Connection timed out\n"); return ret; + } *msg = (struct tracecmd_msg *)msg_tmp; cmd = ntohl((*msg)->cmd); @@ -487,9 +511,12 @@ int tracecmd_msg_initial_setting(int fd, int *cpus, int *pagesize) u32 size = 0; u32 cmd; - ret = tracecmd_msg_recv(fd, buf); - if (ret < 0) + ret = tracecmd_msg_recv_wait(fd, buf, &msg); + if (ret < 0) { + if (ret == -ETIMEDOUT) + warning("Connection timed out\n"); return ret; + } msg = (struct tracecmd_msg *)buf; cmd = ntohl(msg->cmd); @@ -625,9 +652,12 @@ int tracecmd_msg_collect_metadata(int ifd, int ofd) int ret; do { - ret = tracecmd_msg_recv(ifd, buf); + ret = tracecmd_msg_recv_wait(ifd, buf, &msg); if (ret < 0) { - warning("reading client"); + if (ret == -ETIMEDOUT) + warning("Connection timed out\n"); + else + warning("reading client"); return ret; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/