Test to check if setting PROC_CN_MCAST_NOTIFY in proc connector API, allows a thread's non-zero exit status to be returned to proc_filter.
The threads.c program creates 2 child threads. 1st thread handles signal SIGSEGV, and 2nd thread needs to indicate some error condition (value 1) to the kernel, instead of using pthread_exit() with 1.
In both cases, child sends notify_netlink_thread_exit(exit_code) to kernel, to let kernel know it has exited abnormally with exit_code.
Compile: make thread make proc_filter To see non-zero exit notifications, run: ./proc_filter -f Run threads code in another window: ./threads The above will also send SIGSEGV to one of the threads created. After you see the proc_filter display both tids, kill it: [Ctrl-C] in the window where "./proc_filter -f" is being run. The results will be printed in the "./threads" window.
Signed-off-by: Anjali Kulkarni anjali.k.kulkarni@oracle.com --- tools/testing/selftests/connector/Makefile | 23 +- .../testing/selftests/connector/proc_filter.c | 34 ++- tools/testing/selftests/connector/thread.c | 202 ++++++++++++++++++ .../selftests/connector/thread_filter.c | 96 +++++++++ 4 files changed, 348 insertions(+), 7 deletions(-) create mode 100644 tools/testing/selftests/connector/thread.c create mode 100644 tools/testing/selftests/connector/thread_filter.c
diff --git a/tools/testing/selftests/connector/Makefile b/tools/testing/selftests/connector/Makefile index 92188b9bac5c..bf335826bc3b 100644 --- a/tools/testing/selftests/connector/Makefile +++ b/tools/testing/selftests/connector/Makefile @@ -1,5 +1,26 @@ # SPDX-License-Identifier: GPL-2.0 -CFLAGS += -Wall $(KHDR_INCLUDES) +KERNEL="../../../.." + +CFLAGS += -Wall $(KHDR_INCLUDES) -I $(KERNEL)/include/uapi -I $(KERNEL)/include + +proc_filter: proc_filter.o + cc proc_filter.o -o proc_filter + +proc_filter.o: proc_filter.c + cc -c proc_filter.c -o proc_filter.o $(CFLAGS) + +thread: thread.o thread_filter.o + cc thread.o thread_filter.o -o thread + +thread.o: thread.c $(DEPS) + cc -c thread.c -o thread.o $(CFLAGS) + +thread_filter.o: thread_filter.c + cc -c thread_filter.c -o thread_filter.o $(CFLAGS) + +define EXTRA_CLEAN + rm *.o thread +endef
TEST_GEN_PROGS = proc_filter
diff --git a/tools/testing/selftests/connector/proc_filter.c b/tools/testing/selftests/connector/proc_filter.c index 4a825b997666..2374c7d9c7b7 100644 --- a/tools/testing/selftests/connector/proc_filter.c +++ b/tools/testing/selftests/connector/proc_filter.c @@ -1,4 +1,9 @@ // SPDX-License-Identifier: GPL-2.0-only +/* + * Author: Anjali Kulkarni anjali.k.kulkarni@oracle.com + * + * Copyright (c) 2024 Oracle and/or its affiliates. + */
#include <sys/types.h> #include <sys/epoll.h> @@ -28,6 +33,7 @@ volatile static int interrupted; static int nl_sock, ret_errno, tcount; static struct epoll_event evn; +FILE *file = NULL;
static int filter;
@@ -37,6 +43,8 @@ static int filter; #define Printf ksft_print_msg #endif
+#define EXIT_LOG + int send_message(void *pinp) { char buff[NL_MESSAGE_SIZE]; @@ -146,6 +154,12 @@ int handle_packet(char *buff, int fd, struct proc_event *event) tcount++; switch (event->what) { case PROC_EVENT_EXIT: +#ifdef EXIT_LOG + fprintf(file, "pid %d tgid %d code %d\n", + event->event_data.exit.process_pid, + event->event_data.exit.process_tgid, + event->event_data.exit.exit_code); +#endif Printf("Exit process %d (tgid %d) with code %d, signal %d\n", event->event_data.exit.process_pid, event->event_data.exit.process_tgid, @@ -279,17 +293,24 @@ int main(int argc, char *argv[]) exit(1); }
+#ifdef EXIT_LOG + file = fopen("exit.log", "w"); + if (file == NULL) { + perror("Error opening file exit.log"); + close(nl_sock); + close(epoll_fd); + exit(1); + } +#endif + while (!interrupted) { err = handle_events(epoll_fd, &proc_ev); if (err < 0) { if (ret_errno == EINTR) continue; - if (err == -2) - close(nl_sock); - if (err == -3) { - close(nl_sock); - close(epoll_fd); - } + close(nl_sock); + close(epoll_fd); + fclose(file); exit(1); } } @@ -304,6 +325,7 @@ int main(int argc, char *argv[])
close(epoll_fd); close(nl_sock); + fclose(file);
printf("Done total count: %d\n", tcount); exit(0); diff --git a/tools/testing/selftests/connector/thread.c b/tools/testing/selftests/connector/thread.c new file mode 100644 index 000000000000..afab96b9fed9 --- /dev/null +++ b/tools/testing/selftests/connector/thread.c @@ -0,0 +1,202 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Author: Anjali Kulkarni anjali.k.kulkarni@oracle.com + * + * Copyright (c) 2024 Oracle and/or its affiliates. + */ + +#include <pthread.h> +#include <stdio.h> +#include <unistd.h> +#include <stdlib.h> +#include <signal.h> + +/* + * This code tests a thread exit notification when thread exits abnormally. + * Normally, when a thread exits abnormally, the kernel is not aware of the + * exit code. This is usually only conveyed from child to parent via the + * pthread_exit() and pthread_join() calls. Sometimes, however, a parent + * process cannot monitor all child processes via pthread_join(), particularly + * when there is a huge amount of child processes. In this case, the parent + * has created the child with PTHREAD_CREATE_DETACHED attribute. + * To fix this problem, either when child wants to convey non-zero exit via + * pthread_exit() or in a signal handler, the child can notify the kernel's + * connector module it's exit status via a netlink call with new type + * PROC_CN_MCAST_NOTIFY. (Implemented in the thread_filter.c file). + * This will send the exit code from the child to the kernel, which the kernel + * can later return to proc_filter program when the child actually exits. + * To test this usecase: + * Compile: + * make thread + * make proc_filter + * To see non-zero exit notifications, run: + * ./proc_filter -f + * Start the threads code, creating 2 threads, in another window: + * ./threads + * The above will also send SIGSEGV to one of the threads created. + * After you see the proc_filter display both tids, kill it: + * [Ctrl-C] in the window where "./proc_filter -f" is being run. + * The results will be printed in the "./threads" window. + */ + +extern int notify_netlink_thread_exit(unsigned int exit_code); + +static void sigsegvh(int sig) +{ + unsigned int exit_code = (unsigned int) sig; + /* + * Send any non-zero value to get a notification. Here we are + * sending the signal number for SIGSEGV which is 11 + */ + notify_netlink_thread_exit(exit_code); +} + +void *threadc1(void *ptr) +{ + signal(SIGSEGV, sigsegvh); + + *(int *)ptr = gettid(); + + printf("Child 1 thread id %d, handling SIGSEGV\n", gettid()); + sleep(10); + pthread_exit(NULL); +} + +void *threadc2(void *ptr) +{ + int exit_val = 1; + + *(int *)ptr = gettid(); + + printf("Child 2 thread id %d, wants to exit with value %d\n", + gettid(), exit_val); + sleep(2); + notify_netlink_thread_exit(exit_val); + pthread_exit(NULL); +} + +static void verify_exit_status(int tid1, int tid2) +{ + int found1 = 0, found2 = 0; + int pid, tgid, exit_code; + size_t size = 1024; + FILE *file; + char *data; + + data = malloc(size * sizeof(char)); + if (data == NULL) { + perror("malloc for data failed"); + exit(1); + } + + file = fopen("exit.log", "r"); + if (file == NULL) { + perror("fopen of exit.log failed"); + free(data); + exit(1); + } + + while (getline(&data, &size, file) != -1) { + sscanf(data, "pid %d tgid %d code %d", + &pid, &tgid, &exit_code); + + if (tgid != getpid()) { + continue; + } + + if (pid == tid1) { + if (exit_code == 11) { + printf("Successful notification of SIGSEGV, tid %d\n", + pid); + } else { + printf("Failure SIGSEGV tid %d, exit code %d\n", + pid, exit_code); + } + found1 = 1; + } else if (pid == tid2) { + if (exit_code == 1) { + printf("Successful notification of thread exit tid %d\n", + pid); + } else { + printf("Failure thread exit tid %d, exit code %d\n", + pid, exit_code); + } + found2 = 1; + } + } + + if (!found1) + printf("tid %d not present in exit.log file\n", tid1); + + if (!found2) + printf("tid %d not present in exit.log file\n", tid2); + + fclose(file); + free(data); +} + +static inline void init_threads(pthread_attr_t *attr) +{ + int ret; + + ret = pthread_attr_init(attr); + if (ret != 0) { + perror("pthread_attr_init failed"); + exit(ret); + } + + ret = pthread_attr_setdetachstate(attr, PTHREAD_CREATE_DETACHED); + if (ret != 0) { + perror("pthread_attr_setdetachstate failed"); + exit(ret); + } +} + +static inline void destroy_thread_attr(pthread_attr_t *attr) +{ + int ret; + + ret = pthread_attr_destroy(attr); + if (ret != 0) { + perror("pthread_attr_destroy failed"); + exit(ret); + } +} + +int main(int argc, char **argv) +{ + pthread_t thread1, thread2; + pthread_attr_t attr1, attr2; + int tid1, tid2, ret; + + init_threads(&attr1); + ret = pthread_create(&thread1, &attr1, *threadc1, &tid1); + if (ret != 0) { + perror("pthread_create failed"); + exit(ret); + } + + init_threads(&attr2); + ret = pthread_create(&thread2, &attr2, *threadc2, &tid2); + if (ret != 0) { + perror("pthread_create failed"); + exit(ret); + } + + sleep(1); + + /* Send SIGSEGV to tid1 */ + kill(tid1, SIGSEGV); + + /* Wait for children to exit or be killed and for exit.log to + * be generated by ./proc_filter + */ + sleep(10); + + verify_exit_status(tid1, tid2); + + destroy_thread_attr(&attr1); + destroy_thread_attr(&attr2); + + exit(0); +} diff --git a/tools/testing/selftests/connector/thread_filter.c b/tools/testing/selftests/connector/thread_filter.c new file mode 100644 index 000000000000..3da740aa7537 --- /dev/null +++ b/tools/testing/selftests/connector/thread_filter.c @@ -0,0 +1,96 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Author: Anjali Kulkarni anjali.k.kulkarni@oracle.com + * + * Copyright (c) 2024 Oracle and/or its affiliates. + */ + +#include <sys/types.h> +#include <sys/epoll.h> +#include <sys/socket.h> +#include <linux/netlink.h> +#include <linux/connector.h> +#include <linux/cn_proc.h> + +#include <stddef.h> +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <strings.h> +#include <errno.h> +#include <signal.h> +#include <string.h> + +#define NL_MESSAGE_SIZE (sizeof(struct nlmsghdr) + sizeof(struct cn_msg) + \ + sizeof(struct proc_input)) + +/* + * Send PROC_CN_MCAST_NOTIFY type notification to the connector code in kernel. + * This will send the exit_code specified by user to the connector layer, so + * it can send a notification for that event to any listening process + */ +int send_message(int nl_sock, unsigned int exit_code) +{ + char buff[NL_MESSAGE_SIZE]; + struct nlmsghdr *hdr; + struct cn_msg *msg; + + hdr = (struct nlmsghdr *)buff; + hdr->nlmsg_len = NL_MESSAGE_SIZE; + hdr->nlmsg_type = NLMSG_DONE; + hdr->nlmsg_flags = 0; + hdr->nlmsg_seq = 0; + hdr->nlmsg_pid = getpid(); + + msg = (struct cn_msg *)NLMSG_DATA(hdr); + msg->id.idx = CN_IDX_PROC; + msg->id.val = CN_VAL_PROC; + msg->seq = 0; + msg->ack = 0; + msg->flags = 0; + + msg->len = sizeof(struct proc_input); + ((struct proc_input *)msg->data)->mcast_op = + PROC_CN_MCAST_NOTIFY; + ((struct proc_input *)msg->data)->uexit_code = exit_code; + + if (send(nl_sock, hdr, hdr->nlmsg_len, 0) == -1) { + perror("send failed"); + return -errno; + } + return 0; +} + +int notify_netlink_thread_exit(unsigned int exit_code) +{ + struct sockaddr_nl sa_nl; + int err = 0; + int nl_sock; + + nl_sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR); + + if (nl_sock == -1) { + perror("socket failed"); + return -errno; + } + + bzero(&sa_nl, sizeof(sa_nl)); + sa_nl.nl_family = AF_NETLINK; + sa_nl.nl_groups = CN_IDX_PROC; + sa_nl.nl_pid = gettid(); + + if (bind(nl_sock, (struct sockaddr *)&sa_nl, sizeof(sa_nl)) == -1) { + perror("bind failed"); + close(nl_sock); + return -errno; + } + + err = send_message(nl_sock, exit_code); + + close(nl_sock); + + if (err < 0) + return err; + + return 0; +}