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author | Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com> | 2014-07-11 00:58:29 +0000 |
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committer | Steven Rostedt <rostedt@goodmis.org> | 2016-03-21 17:18:44 -0400 |
commit | 8232b403ffd064fc100d5723c16069cda4ca49e4 (patch) | |
tree | 6ea50a31ff2e06ab58d2942d52846e1d8c883c6a | |
parent | cc042aba4a97aea452c7943a00d0147fcc5aa7ce (diff) | |
download | trace-cmd-8232b403ffd064fc100d5723c16069cda4ca49e4.tar.gz |
trace-cmd/msg: Use poll(2) to wait for a message
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
Link: http://lkml.kernel.org/r/20140711005829.25516.75538.stgit@yuno-kbuild.novalocal
Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-rw-r--r-- | trace-msg.c | 42 |
1 files changed, 36 insertions, 6 deletions
diff --git a/trace-msg.c b/trace-msg.c index 0fcaf5bd..0c95327e 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; } |