Disable preemption inside the PBM-functions

since all of those operate on shared data structures and therefore are
mostly critical sections.

kernel/behave.c

@@ -340,7 +340,6 @@ int pbm_task_start(PBM* pbm, uint8_t type, struct task_struct* proc) {
 
 /* Conclude the last task of the given PBM */
 int pbm_task_end(PBM* pbm) {
-	unsigned long irq_flags;
     int read_error;
 	struct perf_event *pevent;
 	u64 perf_counter;
@@ -379,11 +378,8 @@ int pbm_task_end(PBM* pbm) {
 		pbm->last->count = perf_counter;
 	}
 
-	// disable performance counter while preventing context switching
-	local_irq_save(irq_flags);
 	perf_event_disable(pevent);
 	perf_event_release_kernel(pevent);
-	local_irq_restore(irq_flags);
     pevent = NULL;
 
     printk(KERN_WARNING "TASK: %u | ...Counting stopped: %llu instr.\n", current->pid, perf_counter);
@@ -449,8 +445,6 @@ int pbm_task_end(PBM* pbm) {
  * run (current == child) otherwise the perf counting will fail!
  */
 int pbm_fork(struct task_struct* proc, pid_t parent_pid, pbm_NODE* fork_node) {
-	unsigned long irq_flags;
-
 	PBM* parent_pbm;
     PBM* child_pbm;
 
@@ -459,13 +453,10 @@ int pbm_fork(struct task_struct* proc, pid_t parent_pid, pbm_NODE* fork_node) {
      * pbm_fork_parent_new_task() to not be called but pbm_fork() since the child is "mpirun" so we
      * put the initialization in here instead of into pbm_fork_parent_new_task().
      */
-	// avoid context switching during initialization by disabling interrupts
-	local_irq_save(irq_flags);
 	if (!is_initialized) {
 		pbm_init();
 		is_initialized = 1;
 	}
-	local_irq_restore(irq_flags);
 
 	child_pbm = get_pbm_by_pid(proc->pid);
 	parent_pbm = get_pbm_by_pid(parent_pid);
@@ -532,8 +523,10 @@ int pbm_fork(struct task_struct* proc, pid_t parent_pid, pbm_NODE* fork_node) {
     //        only one before the join-operation)
     //      * child_pbm->root != NULL: since the previously called pbm_task_start() should have
     //        written to that
-    child_pbm->root->next_sib = fork_node->children;
-    fork_node->children = child_pbm->root;
+    if (fork_node) {
+        child_pbm->root->next_sib = fork_node->children;
+        fork_node->children = child_pbm->root;
+    }
 
     return 1;
 }

kernel/exit.c

@@ -767,6 +767,7 @@ void __noreturn do_exit(long code)
 	struct task_struct *tsk = current;
 	int group_dead;
 
+    preempt_disable();
 	// call the readout before the process is terminated
 	if (is_relevant_process(tsk)) {
 		pbm_exit(tsk->pid, tsk->real_parent->pid);
@@ -775,6 +776,7 @@ void __noreturn do_exit(long code)
 		pbm_join_and_print_graph_self(tsk->pid);
 	}
     printk(KERN_EMERG "EXIT: %u, CMD: '%s', PARENT-CMD: '%s', PTR: %llu\n", tsk->pid, tsk->comm, tsk->real_parent->comm, (u64)tsk);
+    preempt_enable();
 
 	TASKS_RCU(int tasks_rcu_i);
 

kernel/fork.c

@@ -2021,10 +2021,12 @@ long _do_fork(unsigned long clone_flags,
 	fork_date = NULL;
 
 	// FIXME: This will not get called for mpirun since then bash will be the parent here
+	preempt_disable();
 	if (is_relevant_process(current)) {
 		printk(KERN_EMERG "DO FORK CALLED by: '%s' %u\n", current->comm ,parent_pid);
 		fork_date = pbm_fork_parent_new_task(current);
 	}
+	preempt_enable();
 
 	/*
 	 * Determine whether and which event to report to ptracer.  When
@@ -2084,12 +2086,14 @@ long _do_fork(unsigned long clone_flags,
 		// FIXME: The problem is that at this stage we can not identify the MPIrun process since
 		//        the p->comm is not up to date yet so we simply record all bash childs which is
 		//        rather wasteful!
+		preempt_disable();
 		if (is_relevant_process(p) || (strcmp(p->comm, "bash") == 0)) {
 			// At this point p->comm is not up to date but shows the command of the parent!
 			printk(KERN_EMERG "FORKED!!!!: %u, Parent: %s, Super-Parent:%s\n",
 					p->pid, p->comm, p->real_parent->real_parent->comm);
 			pbm_fork(p, parent_pid, fork_date);
 		}
+		preempt_enable();
 	} else {
 		nr = PTR_ERR(p);
 	}