Attachment 299872 Details for Bug 439999 – Testcase to reproduce the kernel hang

Testcase to reproduce the kernel hang

setitimer.c (text/x-csrc), 3.51 KB, created by Jan Lieskovsky on 2008-04-01 10:09:19 UTC

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Creator: Jan Lieskovsky

Created: 2008-04-01 10:09:19 UTC

Size: 3.51 KB

patch

obsolete

>#include <sys/types.h>
>#include <sys/wait.h>
>#include <sys/time.h>
>#include <sys/ptrace.h>
>#include <assert.h>
>#include <stdio.h>
>#include <unistd.h>
>#include <linux/ptrace.h>
>#include <stdbool.h>
>#include <sys/user.h>
>#include <sys/prctl.h>
>#include <stdlib.h>
>#include <asm/unistd.h>
>#include <sched.h>
>#include <errno.h>
>#include <string.h>
>
>
>#ifndef NDEBUG
># define dprintf(x...) fprintf(stderr, x)
>#else
># define dprintf(x...)
>#endif
>
>typedef enum { SYSCALLENTRY, SYSCALLEXIT } state_t;
>
>int main(int argc, char **argv)
>{
>    int status;
>    pid_t child, pid;
>    state_t state = 0;
>    struct itimerval value, ovalue;
>    struct user_regs_struct regs;
>
>    switch (child = fork()) 
>    {
>        case 0:
>            /* set up deathsig */
>            prctl(PR_SET_PDEATHSIG, SIGKILL);
>
>            /* setup tracing */
>            ptrace(PTRACE_TRACEME, 0, NULL, NULL);
>
>            /* indicate i'm ready for tracing */
>            asm("int3");
>
>            /* setup timervals */
>            value.it_value.tv_sec = 0;
>            value.it_value.tv_usec = 10;
>            value.it_interval.tv_sec = -1;
>            value.it_interval.tv_usec = -1;
>
>            while (true) {
>                /* NOTE: tracer stops me getting alarms */
>                setitimer(ITIMER_REAL, &value, NULL);
>            }
>            return 1;
>        case -1:
>            dprintf("fork failed, %s\n", strerror(errno));
>            return 1;
>        default:
>            dprintf("child created, pid %d\n", child);
>            waitpid(child, &status, 0);
>    }
>
>    ptrace(PTRACE_SETOPTIONS, child, 0, PTRACE_O_TRACESYSGOOD);
>    ptrace(PTRACE_SYSCALL, child, NULL, NULL);
>
>    while ((pid = waitpid(-1, &status, 0)) != -1) {
>        int sig = 0;
>
>        if (pid != child) {
>            dprintf("%d is not my child, unusual...\n", pid);
>        }
>        
>        if (WIFEXITED(status)) {
>            dprintf("child exited with %d\n", WEXITSTATUS(status));
>            return WEXITSTATUS(status);
>        } else if (WIFSIGNALED(status)) {
>            dprintf("child killed with %d\n", WTERMSIG(status));
>            return 0x80 | WTERMSIG(status);
>        } else if (WIFSTOPPED(status)) {
>            if (WSTOPSIG(status) == (SIGTRAP | 0x80)) {
>                ptrace(PTRACE_GETREGS, pid, 0, &regs);
>        
>                /* handle syscall entry / exit */
>                switch (state) {
>                    case SYSCALLENTRY:
>                        dprintf("syscall %lx entry\n", regs.orig_rax);
>                        
>                        /* change state */
>                        state = SYSCALLEXIT;
>                        break;
>                    case SYSCALLEXIT:
>                        dprintf("syscall %lx exit, returns %#x\n", regs.orig_rax, regs.rax);
>
>                        /* reset the state */
>                        state = SYSCALLENTRY;
>                        break;
>                }
>            } else if (WSTOPSIG(status) == SIGTRAP) {
>                dprintf("child trapped, unusual\n");
>                sig = WSTOPSIG(status);
>            } else {
>                dprintf("it stopped with %d\n", WSTOPSIG(status));
>                sig = WSTOPSIG(status);
>            }
>        } else {
>            dprintf("no idea why it stopped, this is odd\n");
>        }
>        
>        /* continue the child, passing sig if sig is not an alarm */
>        if (sig != SIGALRM) {
>            ptrace(PTRACE_SYSCALL, pid, NULL, sig);
>        } else {
>            ptrace(PTRACE_SYSCALL, pid, NULL, NULL);
>        }
>    }
>
>    dprintf("waitpid() fails, %s\n", strerror(errno));
>    return 1;
>}

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