守护进程：看门狗watchdog的添加 |
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本文为项目开发总结的原创文档。
本项目，添加一个watchdog守护进程，用来监控环境的三大进程mozart、bitbox、mplayer，任何一个进程出现故障，整个环境进行重启。 首先有通过版级驱动/arch/mips/xburst/soc-x1000/common# vim reset.c 找到与看门狗有关的code[同事发现，牛！]；因此主要是将核心代码从内核空间搬移到用户空间，及如何监控应用层的进程。 整体实现思路： 1.创建一个进程作为守护进程：watchdog 进程的添加： 在configs下添加watchdog.mak; 在src下添加watchdog包，用于加入watchdog相关的code；Makefile; 进程的启动：在app.c中的startall中调用mozart_system("watchdog -b"); 2.调整进程优先级： 1）如何查看进程的优先级 2）如何修改进程的优先级； 3.watchdog守护进程如何监控mozart和bitbox和mplayer 我们知道内核会通过/proc虚拟文件系统导出系统中正在运行的进程信息，每个进程都有一个/proc/目录。因此我们可以将检测进程是否存在转换为检测/proc/目录是否存在，这样就简单多了。 如下文详细代码中的processExists；
实现难点突破： 用户空间和内核空间操作的都是虚拟地址。 1）如果是拿到的是物理地址，用户空间可以通过mmap的方式将物理地址转成虚拟地址（每一次的地址值都不一样），可以直接对这个虚拟地址赋值。 如下： static int dev_fd; dev_fd = open("/dev/mem", O_RDWR | O_NDELAY); if (dev_fd 65535) time = 65535; #if 0 outl(1 = 1; } printf("Current process %s is not Exist!!!!\n",process_name); return false; } static char *signal_str[] = { [1] = "SIGHUP", [2] = "SIGINT", [3] = "SIGQUIT", [4] = "SIGILL", [5] = "SIGTRAP", [6] = "SIGABRT", [7] = "SIGBUS", [8] = "SIGFPE", [9] = "SIGKILL", [10] = "SIGUSR1", [11] = "SIGSEGV", [12] = "SIGUSR2", [13] = "SIGPIPE", [14] = "SIGALRM", [15] = "SIGTERM", [16] = "SIGSTKFLT", [17] = "SIGCHLD", [18] = "SIGCONT", [19] = "SIGSTOP", [20] = "SIGTSTP", [21] = "SIGTTIN", [22] = "SIGTTOU", [23] = "SIGURG", [24] = "SIGXCPU", [25] = "SIGXFSZ", [26] = "SIGVTALRM", [27] = "SIGPROF", [28] = "SIGWINCH", [29] = "SIGIO", [30] = "SIGPWR", [31] = "SIGSYS", [34] = "SIGRTMIN", [35] = "SIGRTMIN+1", [36] = "SIGRTMIN+2", [37] = "SIGRTMIN+3", [38] = "SIGRTMIN+4", [39] = "SIGRTMIN+5", [40] = "SIGRTMIN+6", [41] = "SIGRTMIN+7", [42] = "SIGRTMIN+8", [43] = "SIGRTMIN+9", [44] = "SIGRTMIN+10", [45] = "SIGRTMIN+11", [46] = "SIGRTMIN+12", [47] = "SIGRTMIN+13", [48] = "SIGRTMIN+14", [49] = "SIGRTMIN+15", [50] = "SIGRTMAX-14", [51] = "SIGRTMAX-13", [52] = "SIGRTMAX-12", [53] = "SIGRTMAX-11", [54] = "SIGRTMAX-10", [55] = "SIGRTMAX-9", [56] = "SIGRTMAX-8", [57] = "SIGRTMAX-7", [58] = "SIGRTMAX-6", [59] = "SIGRTMAX-5", [60] = "SIGRTMAX-4", [61] = "SIGRTMAX-3", [62] = "SIGRTMAX-2", [63] = "SIGRTMAX-1", [64] = "SIGRTMAX", }; static void usage(const char *app_name) { printf("%s [-f file] -h\n" " -h help (show this usage text)\n" " -f file\n", app_name); return; } void sig_handler(int signo) { char cmd[64] = {}; void *array[10]; int size = 0; char **strings = NULL; int i = 0; #if 0 printf("\n\n[%s: %d] bitbox crashed by signal %s.\n", __func__, __LINE__, signal_str[signo]); printf("Call Trace:\n"); size = backtrace(array, 10); strings = backtrace_symbols(array, size); if (strings) { for (i = 0; i < size; i++) printf (" %s\n", strings[i]); free (strings); } else { printf("Not Found\n\n"); } if (signo == SIGSEGV || signo == SIGBUS || signo == SIGTRAP || signo == SIGABRT) { sprintf(cmd, "cat /proc/%d/maps", getpid()); printf("Process maps:\n"); system(cmd); } #else wdt_stop_count(); #endif exit(-1); } int main(int argc, char **argv) { int c = -1; int daemonize = 0; printf("watchdog V1.7 start!!!!@_@\n"); signal(SIGPIPE, SIG_IGN); signal(SIGINT, sig_handler); signal(SIGTERM, sig_handler); signal(SIGBUS, sig_handler); signal(SIGSEGV, sig_handler); signal(SIGABRT, sig_handler); while (1) { c = getopt(argc, argv, "bBf:h"); if (c < 0) break; switch (c) { case 'b': case 'B': daemonize = 1; break; case 'f': break; case 'h': return 0; default: return -1; } } /* run in the background */ if (daemonize) { if (daemon(0, 1)) { perror("daemon"); return -1; } } while(1) { if(processExists("mozart")==true && processExists("bitbox")==true && processExists("mplayer")==true) { // printf("Both mozart and bitbox and mplayer are exists!!!!!\n"); wdt_start_count(20000); sleep(10); } else { printf(" mozart or bitbox or mplayer is not exist, Reboot!!!!! \n"); printf("Mozart process exist ???: %d\n",processExists("mozart")); printf("BitBox process exist ???: %d\n",processExists("bitbox")); printf("Mplayer process exist ???: %d\n",processExists("mplayer")); break; } } }
程序运行起来后，通过ps可查看到： S 0 241 1 7868 716 0:0 13:16 00:00:01 watchdog -b
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