Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752124AbaGKA7e (ORCPT ); Thu, 10 Jul 2014 20:59:34 -0400 Received: from mail9.hitachi.co.jp ([133.145.228.44]:35714 "EHLO mail9.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751280AbaGKA6f (ORCPT ); Thu, 10 Jul 2014 20:58:35 -0400 X-AuditID: 85900ec0-d312bb9000001514-9b-53bf36b78778 Subject: [PATCH V4 2/5] trace-cmd/msg: Use poll(2) to wait for a message From: Yoshihiro YUNOMAE To: Steven Rostedt Cc: Hidehiro Kawai , Masami Hiramatsu , yrl.pp-manager.tt@hitachi.com, linux-kernel@vger.kernel.org, Aaron Fabbri Date: Fri, 11 Jul 2014 00:58:29 +0000 Message-ID: <20140711005829.25516.75538.stgit@yuno-kbuild.novalocal> In-Reply-To: <20140711005824.25516.24498.stgit@yuno-kbuild.novalocal> References: <20140711005824.25516.24498.stgit@yuno-kbuild.novalocal> User-Agent: StGit/0.17-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAA== 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. Changes in V4: Change the argument of tracecmd_msg_recv_wait() Fix some typos Signed-off-by: Yoshihiro YUNOMAE --- trace-msg.c | 42 ++++++++++++++++++++++++++++++++++++------ 1 file changed, 36 insertions(+), 6 deletions(-) diff --git a/trace-msg.c b/trace-msg.c index 08fa2a6..db48365 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/