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author | Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com> | 2012-08-09 21:31:30 +0900 |
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committer | Rusty Russell <rusty@rustcorp.com.au> | 2012-09-28 15:05:13 +0930 |
commit | 108fc82596e3b66b819df9d28c1ebbc9ab5de14c (patch) | |
tree | 66c051fac35849764818a47aa278d073af72b182 /tools/virtio/virtio-trace/trace-agent-ctl.c | |
parent | 8ca84a50e5b39487ea1de8809d0ee1c8474f6a5c (diff) | |
download | linux-stable-108fc82596e3b66b819df9d28c1ebbc9ab5de14c.tar.gz linux-stable-108fc82596e3b66b819df9d28c1ebbc9ab5de14c.tar.bz2 linux-stable-108fc82596e3b66b819df9d28c1ebbc9ab5de14c.zip |
tools: Add guest trace agent as a user tool
This patch adds a user tool, "trace agent" for sending trace data of a guest to
a Host in low overhead. This agent has the following functions:
- splice a page of ring-buffer to read_pipe without memory copying
- splice the page from write_pipe to virtio-console without memory copying
- write trace data to stdout by using -o option
- controlled by start/stop orders from a Host
Changes in v2:
- Cleanup (change fprintf() to pr_err() and an include guard)
Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Acked-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'tools/virtio/virtio-trace/trace-agent-ctl.c')
-rw-r--r-- | tools/virtio/virtio-trace/trace-agent-ctl.c | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/tools/virtio/virtio-trace/trace-agent-ctl.c b/tools/virtio/virtio-trace/trace-agent-ctl.c new file mode 100644 index 000000000000..a2d0403c4f94 --- /dev/null +++ b/tools/virtio/virtio-trace/trace-agent-ctl.c @@ -0,0 +1,137 @@ +/* + * Controller of read/write threads for virtio-trace + * + * Copyright (C) 2012 Hitachi, Ltd. + * Created by Yoshihiro Yunomae <yoshihiro.yunomae.ez@hitachi.com> + * Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> + * + * Licensed under GPL version 2 only. + * + */ + +#define _GNU_SOURCE +#include <fcntl.h> +#include <poll.h> +#include <signal.h> +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include "trace-agent.h" + +#define HOST_MSG_SIZE 256 +#define EVENT_WAIT_MSEC 100 + +static volatile sig_atomic_t global_signal_val; +bool global_sig_receive; /* default false */ +bool global_run_operation; /* default false*/ + +/* Handle SIGTERM/SIGINT/SIGQUIT to exit */ +static void signal_handler(int sig) +{ + global_signal_val = sig; +} + +int rw_ctl_init(const char *ctl_path) +{ + int ctl_fd; + + ctl_fd = open(ctl_path, O_RDONLY); + if (ctl_fd == -1) { + pr_err("Cannot open ctl_fd\n"); + goto error; + } + + return ctl_fd; + +error: + exit(EXIT_FAILURE); +} + +static int wait_order(int ctl_fd) +{ + struct pollfd poll_fd; + int ret = 0; + + while (!global_sig_receive) { + poll_fd.fd = ctl_fd; + poll_fd.events = POLLIN; + + ret = poll(&poll_fd, 1, EVENT_WAIT_MSEC); + + if (global_signal_val) { + global_sig_receive = true; + pr_info("Receive interrupt %d\n", global_signal_val); + + /* Wakes rw-threads when they are sleeping */ + if (!global_run_operation) + pthread_cond_broadcast(&cond_wakeup); + + ret = -1; + break; + } + + if (ret < 0) { + pr_err("Polling error\n"); + goto error; + } + + if (ret) + break; + }; + + return ret; + +error: + exit(EXIT_FAILURE); +} + +/* + * contol read/write threads by handling global_run_operation + */ +void *rw_ctl_loop(int ctl_fd) +{ + ssize_t rlen; + char buf[HOST_MSG_SIZE]; + int ret; + + /* Setup signal handlers */ + signal(SIGTERM, signal_handler); + signal(SIGINT, signal_handler); + signal(SIGQUIT, signal_handler); + + while (!global_sig_receive) { + + ret = wait_order(ctl_fd); + if (ret < 0) + break; + + rlen = read(ctl_fd, buf, sizeof(buf)); + if (rlen < 0) { + pr_err("read data error in ctl thread\n"); + goto error; + } + + if (rlen == 2 && buf[0] == '1') { + /* + * If host writes '1' to a control path, + * this controller wakes all read/write threads. + */ + global_run_operation = true; + pthread_cond_broadcast(&cond_wakeup); + pr_debug("Wake up all read/write threads\n"); + } else if (rlen == 2 && buf[0] == '0') { + /* + * If host writes '0' to a control path, read/write + * threads will wait for notification from Host. + */ + global_run_operation = false; + pr_debug("Stop all read/write threads\n"); + } else + pr_info("Invalid host notification: %s\n", buf); + } + + return NULL; + +error: + exit(EXIT_FAILURE); +} |