This series fixes 2 BUGs and 2 causes of master pty open failure. Much of this could have been avoided by not calling the tty driver close() routine if the open() was unsuccessful. Unfortunately, that choice appears cast in stone, as many drivers depend on this behavior for cleanup. Ilya Zykov's latest test jig "stress_test_tty" (included below) passes the parallel open test after applying these patches. peter@kvm:~/src/test$ ./stress_test_tty Thread open has been created. Parent normal exit Normal parent exit 0. (NB: I did add a minor diagnostic to the test jig in pty_exit() so it would print errno on error exit). Peter Hurley (4): pty: Fix BUG()s when ptmx_open() errors out pty: Ignore slave pty close() if never successfully opened tty: Document required behavior of tty driver close() pty: Ignore slave open count for master pty open drivers/tty/pty.c | 15 +++++++++++---- include/linux/tty_driver.h | 1 + 2 files changed, 12 insertions(+), 4 deletions(-) /* * stress_test_tty.c * * Created on: Dec, 2012 * Copyright (C) 2012 Ilya Zykov * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ #include <stdio.h> #include <fcntl.h> #include <sys/ioctl.h> #include <termios.h> #include <stdlib.h> #include <pthread.h> #include <signal.h> #include <errno.h> #define BUF_SIZE 2 #define ERROR_EXIT_CODE 1 #define parent child_id static int mfd=-1, sfd=-1, parent=1; static pthread_t pth_id; static char pty_name[24], buf[]={ '1', '\n' }; static void pty_exit(int ret, char * exit_message){ int err = errno; if (sfd >= 0) close(sfd); if (mfd >= 0) close(mfd); printf("%s %s %s exit %d. \n",exit_message?exit_message:"", ret?"Error":"Normal", parent?"parent":"child", ret?err:ret); exit(ret); } static void pty_init(void){ int ptn; if( (mfd=open("/dev/ptmx", O_RDWR )) < 0 ) pty_exit(ERROR_EXIT_CODE,"Couldn't open /dev/ptmx. \n"); if (ioctl(mfd, TIOCGPTN, &ptn) < 0 ) pty_exit(ERROR_EXIT_CODE,"Couldn't get pty number. \n"); snprintf(pty_name, sizeof(pty_name), "/dev/pts/%d", ptn); //printf("Slave pty name = %s.\n",pty_name); ptn=0; if (ioctl(mfd, TIOCSPTLCK, &ptn) < 0 ) pty_exit(ERROR_EXIT_CODE,"Couldn't unlock pty slave. \n"); if ( (sfd=open(pty_name, O_RDWR )) < 0 ) pty_exit(ERROR_EXIT_CODE, "Couldn't open pty slave. \n"); } static void * pty_thread_open(void * arg) { static char ret[]="Thread open has been created.\n"; printf(ret); do { close(open(pty_name, O_RDWR )); } while(1); return ret; } static void * pty_thread_read(void * arg) { static char ret[]="Thread read has been created.\n"; printf(ret); do { read(sfd, buf, BUF_SIZE); } while(1); return ret; } static void * pty_thread_write(void * arg) { static char ret[]="Thread write has been created.\n"; printf(ret); do { write(mfd, buf, BUF_SIZE); } while(1); return ret; } int main(int argc,char *argv[]) { pty_init(); child_id=fork(); if(parent) { sleep(100); kill(child_id, SIGINT); pty_exit(0,"Parent normal exit\n"); } pthread_create(&pth_id, NULL, &pty_thread_open, 0); /* For WARNINGS. pthread_create(&pth_id, NULL, &pty_thread_write, 0); pthread_create(&pth_id, NULL, &pty_thread_read, 0); */ do { close(sfd); close(mfd); pty_init(); } while(1); return 0; } -- 1.8.1.1 -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
