Commit | Line | Data |
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108fc825 YY |
1 | /* |
2 | * Read/write thread of a guest agent for virtio-trace | |
3 | * | |
4 | * Copyright (C) 2012 Hitachi, Ltd. | |
5 | * Created by Yoshihiro Yunomae <yoshihiro.yunomae.ez@hitachi.com> | |
6 | * Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> | |
7 | * | |
8 | * Licensed under GPL version 2 only. | |
9 | * | |
10 | */ | |
11 | ||
12 | #define _GNU_SOURCE | |
13 | #include <fcntl.h> | |
14 | #include <stdio.h> | |
15 | #include <stdlib.h> | |
16 | #include <unistd.h> | |
17 | #include <sys/syscall.h> | |
18 | #include "trace-agent.h" | |
19 | ||
20 | #define READ_WAIT_USEC 100000 | |
21 | ||
22 | void *rw_thread_info_new(void) | |
23 | { | |
24 | struct rw_thread_info *rw_ti; | |
25 | ||
26 | rw_ti = zalloc(sizeof(struct rw_thread_info)); | |
27 | if (rw_ti == NULL) { | |
28 | pr_err("rw_thread_info zalloc error\n"); | |
29 | exit(EXIT_FAILURE); | |
30 | } | |
31 | ||
32 | rw_ti->cpu_num = -1; | |
33 | rw_ti->in_fd = -1; | |
34 | rw_ti->out_fd = -1; | |
35 | rw_ti->read_pipe = -1; | |
36 | rw_ti->write_pipe = -1; | |
37 | rw_ti->pipe_size = PIPE_INIT; | |
38 | ||
39 | return rw_ti; | |
40 | } | |
41 | ||
42 | void *rw_thread_init(int cpu, const char *in_path, const char *out_path, | |
43 | bool stdout_flag, unsigned long pipe_size, | |
44 | struct rw_thread_info *rw_ti) | |
45 | { | |
46 | int data_pipe[2]; | |
47 | ||
48 | rw_ti->cpu_num = cpu; | |
49 | ||
50 | /* set read(input) fd */ | |
51 | rw_ti->in_fd = open(in_path, O_RDONLY); | |
52 | if (rw_ti->in_fd == -1) { | |
53 | pr_err("Could not open in_fd (CPU:%d)\n", cpu); | |
54 | goto error; | |
55 | } | |
56 | ||
57 | /* set write(output) fd */ | |
58 | if (!stdout_flag) { | |
59 | /* virtio-serial output mode */ | |
60 | rw_ti->out_fd = open(out_path, O_WRONLY); | |
61 | if (rw_ti->out_fd == -1) { | |
62 | pr_err("Could not open out_fd (CPU:%d)\n", cpu); | |
63 | goto error; | |
64 | } | |
65 | } else | |
66 | /* stdout mode */ | |
67 | rw_ti->out_fd = STDOUT_FILENO; | |
68 | ||
69 | if (pipe2(data_pipe, O_NONBLOCK) < 0) { | |
70 | pr_err("Could not create pipe in rw-thread(%d)\n", cpu); | |
71 | goto error; | |
72 | } | |
73 | ||
74 | /* | |
75 | * Size of pipe is 64kB in default based on fs/pipe.c. | |
76 | * To read/write trace data speedy, pipe size is changed. | |
77 | */ | |
78 | if (fcntl(*data_pipe, F_SETPIPE_SZ, pipe_size) < 0) { | |
79 | pr_err("Could not change pipe size in rw-thread(%d)\n", cpu); | |
80 | goto error; | |
81 | } | |
82 | ||
83 | rw_ti->read_pipe = data_pipe[1]; | |
84 | rw_ti->write_pipe = data_pipe[0]; | |
85 | rw_ti->pipe_size = pipe_size; | |
86 | ||
87 | return NULL; | |
88 | ||
89 | error: | |
90 | exit(EXIT_FAILURE); | |
91 | } | |
92 | ||
93 | /* Bind a thread to a cpu */ | |
94 | static void bind_cpu(int cpu_num) | |
95 | { | |
96 | cpu_set_t mask; | |
97 | ||
98 | CPU_ZERO(&mask); | |
99 | CPU_SET(cpu_num, &mask); | |
100 | ||
101 | /* bind my thread to cpu_num by assigning zero to the first argument */ | |
102 | if (sched_setaffinity(0, sizeof(mask), &mask) == -1) | |
103 | pr_err("Could not set CPU#%d affinity\n", (int)cpu_num); | |
104 | } | |
105 | ||
106 | static void *rw_thread_main(void *thread_info) | |
107 | { | |
108 | ssize_t rlen, wlen; | |
109 | ssize_t ret; | |
110 | struct rw_thread_info *ts = (struct rw_thread_info *)thread_info; | |
111 | ||
112 | bind_cpu(ts->cpu_num); | |
113 | ||
114 | while (1) { | |
115 | /* Wait for a read order of trace data by Host OS */ | |
116 | if (!global_run_operation) { | |
117 | pthread_mutex_lock(&mutex_notify); | |
118 | pthread_cond_wait(&cond_wakeup, &mutex_notify); | |
119 | pthread_mutex_unlock(&mutex_notify); | |
120 | } | |
121 | ||
122 | if (global_sig_receive) | |
123 | break; | |
124 | ||
125 | /* | |
126 | * Each thread read trace_pipe_raw of each cpu bounding the | |
127 | * thread, so contention of multi-threads does not occur. | |
128 | */ | |
129 | rlen = splice(ts->in_fd, NULL, ts->read_pipe, NULL, | |
130 | ts->pipe_size, SPLICE_F_MOVE | SPLICE_F_MORE); | |
131 | ||
132 | if (rlen < 0) { | |
133 | pr_err("Splice_read in rw-thread(%d)\n", ts->cpu_num); | |
134 | goto error; | |
135 | } else if (rlen == 0) { | |
136 | /* | |
137 | * If trace data do not exist or are unreadable not | |
138 | * for exceeding the page size, splice_read returns | |
139 | * NULL. Then, this waits for being filled the data in a | |
140 | * ring-buffer. | |
141 | */ | |
142 | usleep(READ_WAIT_USEC); | |
143 | pr_debug("Read retry(cpu:%d)\n", ts->cpu_num); | |
144 | continue; | |
145 | } | |
146 | ||
147 | wlen = 0; | |
148 | ||
149 | do { | |
150 | ret = splice(ts->write_pipe, NULL, ts->out_fd, NULL, | |
151 | rlen - wlen, | |
152 | SPLICE_F_MOVE | SPLICE_F_MORE); | |
153 | ||
154 | if (ret < 0) { | |
155 | pr_err("Splice_write in rw-thread(%d)\n", | |
156 | ts->cpu_num); | |
157 | goto error; | |
158 | } else if (ret == 0) | |
159 | /* | |
160 | * When host reader is not in time for reading | |
161 | * trace data, guest will be stopped. This is | |
162 | * because char dev in QEMU is not supported | |
163 | * non-blocking mode. Then, writer might be | |
164 | * sleep in that case. | |
165 | * This sleep will be removed by supporting | |
166 | * non-blocking mode. | |
167 | */ | |
168 | sleep(1); | |
169 | wlen += ret; | |
170 | } while (wlen < rlen); | |
171 | } | |
172 | ||
173 | return NULL; | |
174 | ||
175 | error: | |
176 | exit(EXIT_FAILURE); | |
177 | } | |
178 | ||
179 | ||
180 | pthread_t rw_thread_run(struct rw_thread_info *rw_ti) | |
181 | { | |
182 | int ret; | |
183 | pthread_t rw_thread_per_cpu; | |
184 | ||
185 | ret = pthread_create(&rw_thread_per_cpu, NULL, rw_thread_main, rw_ti); | |
186 | if (ret != 0) { | |
187 | pr_err("Could not create a rw thread(%d)\n", rw_ti->cpu_num); | |
188 | exit(EXIT_FAILURE); | |
189 | } | |
190 | ||
191 | return rw_thread_per_cpu; | |
192 | } |