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/usr/share/systemtap/runtime

Name	Size	Mode	Actions
dyninst/	-	0755	rm
linux/	-	0755	rm
softfloat/	-	0755	rm
transport/	-	0755	rm
unwind/	-	0755	rm
addr-map.c	523	0644	edit dl rm
addr-map.h	1156	0644	edit dl rm
alloc.c	498	0644	edit dl rm
arith.c	483	0644	edit dl rm
common_probe_context.h	6576	0644	edit dl rm
common_session_state.h	415	0644	edit dl rm
compatdefs.h	3682	0644	edit dl rm
copy.c	585	0644	edit dl rm
debug.h	485	0644	edit dl rm
io.c	508	0644	edit dl rm
k_syms.h	182	0644	edit dl rm
loc2c-runtime.h	17937	0644	edit dl rm
map-gen.c	25977	0644	edit dl rm
map-stat.c	3589	0644	edit dl rm
map.c	14660	0644	edit dl rm
map.h	5918	0644	edit dl rm
mempool.c	2644	0644	edit dl rm
namespaces.h	487	0644	edit dl rm
pmap-gen.c	8710	0644	edit dl rm
print.c	486	0644	edit dl rm
print.h	872	0644	edit dl rm
print_flush.c	3073	0644	edit dl rm
probe_lock.h	498	0644	edit dl rm
procfs-probes.c	4673	0644	edit dl rm
procfs-probes.h	674	0644	edit dl rm
procfs.c	4021	0644	edit dl rm
proc_fs_compatibility.h	2316	0644	edit dl rm
ptrace_compatibility.h	1512	0644	edit dl rm
regs.c	4280	0644	edit dl rm
regs.h	2352	0644	edit dl rm
runtime.h	928	0644	edit dl rm
runtime_context.h	669	0644	edit dl rm
runtime_defines.h	3582	0644	edit dl rm
softfloat.c	77159	0644	edit dl rm
softfloat.h	5125	0644	edit dl rm
stack-arm.c	1688	0644	edit dl rm
stack-ia64.c	1083	0644	edit dl rm
stack-mips.c	125	0644	edit dl rm
stack-s390.c	2362	0644	edit dl rm
stack.c	21790	0644	edit dl rm
stat-common.c	8486	0644	edit dl rm
stat.c	7421	0644	edit dl rm
stat.h	1964	0644	edit dl rm
stp_helper_lock.h	3669	0644	edit dl rm
stp_string.c	8632	0644	edit dl rm
stp_string.h	598	0644	edit dl rm
stp_task_work.c	3511	0644	edit dl rm
stp_utrace.c	94735	0644	edit dl rm
stp_utrace.h	14010	0644	edit dl rm
sym.c	39757	0644	edit dl rm
sym.h	6539	0644	edit dl rm
syscall.h	17408	0644	edit dl rm
task_finder_vma.c	13290	0644	edit dl rm
time.c	14887	0644	edit dl rm
timer.c	481	0644	edit dl rm
timer.h	482	0644	edit dl rm
uidgid_compatibility.h	603	0644	edit dl rm
unwind.c	47890	0644	edit dl rm
utrace_compatibility.h	3148	0644	edit dl rm
vma.c	9545	0644	edit dl rm
vsprintf.c	24058	0644	edit dl rm
vsprintf.h	1502	0644	edit dl rm

Edit: /usr/share/systemtap/runtime/stp_task_work.c (3511B)

#ifndef _STP_TASK_WORK_C
#define _STP_TASK_WORK_C

#include "linux/task_work_compatibility.h"

#if !defined(STAPCONF_TASK_WORK_ADD_EXPORTED)
// First typedef from the original decls, then #define as typecasted calls.
typedef typeof(&task_work_add) task_work_add_fn;
#define task_work_add (* (task_work_add_fn)kallsyms_task_work_add)
#endif
#if !defined(STAPCONF_TASK_WORK_CANCEL_EXPORTED)
typedef typeof(&task_work_cancel) task_work_cancel_fn;
#define task_work_cancel (* (task_work_cancel_fn)kallsyms_task_work_cancel)
#endif

/* To avoid a crash when a task_work callback gets called after the
 * module is unloaded, keep track of the number of current callbacks. */
static atomic_t stp_task_work_callbacks = ATOMIC_INIT(0);
static DECLARE_WAIT_QUEUE_HEAD(stp_task_work_waitq);

/*
 * stp_task_work_init() should be called before any other
 * stp_task_work_* functions are called to do setup.
 */
static int
stp_task_work_init(void)
{
#if !defined(STAPCONF_TASK_WORK_ADD_EXPORTED)
	/* The task_work_add()/task_work_cancel() functions aren't
	 * exported. Look up those function addresses. */
        kallsyms_task_work_add = (void *)kallsyms_lookup_name("task_work_add");
        if (kallsyms_task_work_add == NULL) {
		_stp_error("Can't resolve task_work_add!");
		return -ENOENT;
        }
#endif
#if !defined(STAPCONF_TASK_WORK_CANCEL_EXPORTED)
        kallsyms_task_work_cancel = (void *)kallsyms_lookup_name("task_work_cancel");
        if (kallsyms_task_work_cancel == NULL) {
		_stp_error("Can't resolve task_work_cancel!");
		return -ENOENT;
        }
#endif
	return 0;
}

/*
 * stap_task_work_exit() should be called when no more
 * stp_task_work_* functions will be called (before module exit).
 *
 * This function makes sure that all the callbacks are finished before
 * letting the module unload.  If the module unloads before a callback
 * is called, the kernel will try to make a function call to an
 * invalid address.
 */
static void
stp_task_work_exit(void)
{
	wait_event(stp_task_work_waitq, !atomic_read(&stp_task_work_callbacks));
}

static void
stp_task_work_get(void)
{
	/*
	 * We use atomic_inc_return() here instead of atomic_inc() because
	 * atomic_inc_return() implies a full memory barrier and we need the
	 * updates to stp_task_work_callbacks to be ordered correctly, otherwise
	 * there could still be a task worker active after stp_task_work_exit()
	 * returns (assuming that no task workers are added *after*
	 * stp_task_work_exit() returns).
	 */
	atomic_inc_return(&stp_task_work_callbacks);
}

static void
stp_task_work_put(void)
{
	if (atomic_dec_and_test(&stp_task_work_callbacks))
		wake_up(&stp_task_work_waitq);
}

/*
 * Our task_work_add() wrapper that remembers that we've got a pending
 * callback.
 */
static int
stp_task_work_add(struct task_struct *task, struct task_work *twork)
{
	int rc;

rc = task_work_add(task, twork, true);
	if (rc == 0)
		stp_task_work_get();
	return rc;
}

/*
 * Our task_work_cancel() wrapper that remembers that a callback has
 * been cancelled.
 */
static struct task_work *
stp_task_work_cancel(struct task_struct *task, task_work_func_t func)
{
	struct task_work *twork;

twork = task_work_cancel(task, func);
	if (twork != NULL)
		stp_task_work_put();
	return twork;
}

/*
 * stp_task_work_func_done() should be called at the very end of a
 * task_work callback function so that we can keep up with callback
 * accounting.
 */
static void
stp_task_work_func_done(void)
{
	stp_task_work_put();
}

#endif /* _STP_TASK_WORK_C */

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