On Sun, 27 Jan 2002 02:00:56 -0800 Swapnil Nagle <swaps@protonic.com> wrote: SN> SN> Have a look at: SN> http://www.scs.ch/~frey/linux/kernelthreads.html SN> SN> or the oprofile.c file in OProfile source code. SN> But I start the thread with kernel_thread in start_kernel: it isn't in a module. And I have another problem also: Here is the code: ---------------------------- int somi_recv_info_d(void *arg) { struct socket *sock; struct sock *sk; mm_segment_t oldfs; struct msghdr msg; struct iovec iov; struct sockaddr_in sin; struct somi_mig_tbl smtab; int ret; strcpy(current->comm, "SOMI_recvd"); daemonize(); /* Set priority, grp, session, etc. so that it belongs to family of kernel threads. */ /* mask all signals except SIGKILL,SIGIO and SIGSTOP */ spin_lock_irq(¤t->sigmask_lock); siginitsetinv(¤t->blocked, sigmask(SIGIO) | sigmask(SIGKILL) | sigmask(SIGSTOP) ); recalc_sigpending(current); spin_unlock_irq(¤t->sigmask_lock); if(sock_create(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &sock) < 0) { #ifdef CONFIG_SOMI_DEBUG printk("SOMI: Can't create socket in somi_recv_info\n"); #endif //CONFIG_SOMI_DEBUG return -1; } if(somi_init_socket(sock, SOMI_RECVD_PORT) < 0) { #ifdef CONFIG_SOMI_DEBUG printk("SOMI: Could not bind\n"); #endif sock_release(sock); return -1; } iov.iov_len = sizeof(struct somi_mig_tbl); iov.iov_base = (char *)&smtab; msg.msg_name = &sin; msg.msg_namelen = sizeof(struct sockaddr_in); msg.msg_iov = &iov; msg.msg_iovlen = 1; msg.msg_control = NULL; msg.msg_controllen = 0; msg.msg_flags = 0; while(1) { oldfs = get_fs(); set_fs(KERNEL_DS); printk("SOMI: before sock_recvmsg\n"); printk("SOMI: This was added to check what the problem with NULL POINTERS is.\n\n");----------> ret = sock_recvmsg(sock, &msg, sizeof(smtab), 0); printk("SOMI: after sock_recvmsg\n"); if(ret != sizeof(smtab)) { #ifdef CONFIG_SOMI_DEBUG ----------> printk("SOMI: Invalid message from %lu:%d; recd %d bytes\n",sin.sin_addr.s_addr, sin.sin_port, ret);#endif break; } else { #ifdef CONFIG_SOMI_DEBUG printk("SOMI: Message recd from %lu:%d:\n",sin.sin_addr.s_addr, sin.sin_port);#endif if(smtab.flag == 0) { // UDP if((sk = udp_v4_lookup(0, 0, smtab.old_ip, smtab.old_port, 0)) == NULL) {#ifdef CONFIG_SOMI_DEBUG printk("SOMI: sk struct not found for modification: port value is %d", ntohs(smtab.old_port));#endif goto loop; } sk->somi_sport = smtab.new_port; if(!smtab.new_ip) { sk->somi_saddr = sin.sin_addr.s_addr; } else sk->somi_saddr = smtab.new_ip; printk("SOMI: set the IP:port to %lu:%d\n", sk->somi_saddr, sk->somi_sport); } } // else loop: set_fs(oldfs); } // while set_fs(oldfs); printk("SOMI: exiting from somi_recvd!\n"); return 0; ---------------------------------- On entering init 6/0, when sending TERM and KILL signals to processes, this thread receives invalid messages (size: -512 bytes). This is printed on the terminal, and then this goes in an infinite loop. I added the 'break' later; It exits, but why should it receive any invalid message, if the kernel gives it a SIGTERM or SIGKILL? Also, another problem I face is: after receiving one or two messages, it again goes in sock_recvmsg(I see the two printk'ed messages: before sock_recvmsg and the NULL pointer one.). The kernel then does a panic, and value of EIP is 0. It tries to access virtual mem. locn. 0. (Shown this place by an arrow in the code). --- - Amit http://amitshah.nav.to/ amitshah@gmx.net -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ IRC Channel: irc.openprojects.net / #kernelnewbies Web Page: http://www.kernelnewbies.org/
