From 185d388e62957871192a06472e3f6abf2b17d324 Mon Sep 17 00:00:00 2001
From: FKHals <5229803-FKHals@users.noreply.gitlab.com>
Date: Mon, 6 Mar 2023 10:25:16 +0100
Subject: [PATCH] Disable preemption inside the PBM-functions
since all of those operate on shared data structures and therefore are
mostly critical sections.
---
kernel/behave.c | 15 ++++-----------
kernel/exit.c | 2 ++
kernel/fork.c | 4 ++++
3 files changed, 10 insertions(+), 11 deletions(-)
diff --git a/kernel/behave.c b/kernel/behave.c
index 4936bc8d2c7e..ad9335c1f5b0 100644
--- a/kernel/behave.c
+++ b/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;
}
diff --git a/kernel/exit.c b/kernel/exit.c
index c86736ac91d5..1db6b15cf9dc 100644
--- a/kernel/exit.c
+++ b/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);
diff --git a/kernel/fork.c b/kernel/fork.c
index b863c1dcb940..e0fbef1bcab2 100644
--- a/kernel/fork.c
+++ b/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);
}
--
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