Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754333AbaLVJwy (ORCPT ); Mon, 22 Dec 2014 04:52:54 -0500 Received: from mail4.hitachi.co.jp ([133.145.228.5]:46649 "EHLO mail4.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754309AbaLVJww (ORCPT ); Mon, 22 Dec 2014 04:52:52 -0500 Subject: [PATCH trace-cmd V5 3/6] trace-cmd/msg: Use poll(2) to wait for a message From: Masami Hiramatsu To: Steven Rostedt Cc: Hidehiro Kawai , yrl.pp-manager.tt@hitachi.com, Aaron Fabbri , linux-kernel@vger.kernel.org, Divya Vyas Date: Mon, 22 Dec 2014 12:47:57 -0500 Message-ID: <20141222174757.10068.60053.stgit@localhost.localdomain> In-Reply-To: <20141222174736.10068.90306.stgit@localhost.localdomain> References: <20141222174736.10068.90306.stgit@localhost.localdomain> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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: Masami Hiramatsu --- Changes in V4: Change the argument of tracecmd_msg_recv_wait() Fix some typos --- trace-msg.c | 42 ++++++++++++++++++++++++++++++++++++------ 1 file changed, 36 insertions(+), 6 deletions(-) diff --git a/trace-msg.c b/trace-msg.c index a97222c..3228559 100644 --- a/trace-msg.c +++ b/trace-msg.c @@ -395,6 +395,27 @@ error: return -ENOMSG; } +#define MSG_WAIT_MSEC 5000 + +/* + * A return value of 0 indicates time-out + */ +static int tracecmd_msg_recv_wait(int fd, 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, msg); +} + static void *tracecmd_msg_buf_access(struct tracecmd_msg *msg, int offset) { return (void *)msg + offset; @@ -405,9 +426,12 @@ static int tracecmd_msg_wait_for_msg(int fd, struct tracecmd_msg *msg) u32 cmd; int ret; - ret = tracecmd_msg_recv(fd, msg); - if (ret < 0) + ret = tracecmd_msg_recv_wait(fd, msg); + if (ret < 0) { + if (ret == -ETIMEDOUT) + warning("Connection timed out\n"); return ret; + } cmd = ntohl(msg->cmd); if (cmd == MSG_CLOSE) @@ -487,9 +511,12 @@ int tracecmd_msg_initial_setting(int fd, int *cpus, int *pagesize) u32 cmd; msg = (struct tracecmd_msg *)buf; - ret = tracecmd_msg_recv(fd, msg); - if (ret < 0) + ret = tracecmd_msg_recv_wait(fd, msg); + if (ret < 0) { + if (ret == -ETIMEDOUT) + warning("Connection timed out\n"); return ret; + } cmd = ntohl(msg->cmd); if (cmd != MSG_TINIT) { @@ -627,9 +654,12 @@ int tracecmd_msg_collect_metadata(int ifd, int ofd) msg = (struct tracecmd_msg *)buf; do { - ret = tracecmd_msg_recv(ifd, msg); + ret = tracecmd_msg_recv_wait(ifd, 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 majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/