Fix: ACCESS_ONCE() removed in kernel 4.15

[lttng-modules.git] / probes / lttng-kretprobes.c

diff --git a/probes/lttng-kretprobes.c b/probes/lttng-kretprobes.c
index d71090a2bc321edcac3695c774508c1d0d025655..49b7de82d86e32ed0a9afd81d971159f43d80aa4 100644 (file)
--- a/probes/lttng-kretprobes.c
+++ b/probes/lttng-kretprobes.c
@@ -1,5 +1,5 @@
 /*
- * probes/lttng-kretprobes.c
+* probes/lttng-kretprobes.c
  *
  * LTTng kretprobes integration module.
  *
@@ -24,10 +24,11 @@
 #include <linux/kprobes.h>
 #include <linux/slab.h>
 #include <linux/kref.h>
-#include "../lttng-events.h"
-#include "../wrapper/ringbuffer/frontend_types.h"
-#include "../wrapper/vmalloc.h"
-#include "../lttng-tracer.h"
+#include <lttng-events.h>
+#include <wrapper/ringbuffer/frontend_types.h>
+#include <wrapper/vmalloc.h>
+#include <wrapper/irqflags.h>
+#include <lttng-tracer.h>
 
 enum lttng_kretprobe_type {
        EVENT_ENTRY = 0,
@@ -50,6 +51,10 @@ int _lttng_kretprobes_handler(struct kretprobe_instance *krpi,
                container_of(krpi->rp, struct lttng_krp, krp);
        struct lttng_event *event =
                lttng_krp->event[type];
+       struct lttng_probe_ctx lttng_probe_ctx = {
+               .event = event,
+               .interruptible = !lttng_regs_irqs_disabled(regs),
+       };
        struct lttng_channel *chan = event->chan;
        struct lib_ring_buffer_ctx ctx;
        int ret;
@@ -58,17 +63,17 @@ int _lttng_kretprobes_handler(struct kretprobe_instance *krpi,
                unsigned long parent_ip;
        } payload;
 
-       if (unlikely(!ACCESS_ONCE(chan->session->active)))
+       if (unlikely(!READ_ONCE(chan->session->active)))
                return 0;
-       if (unlikely(!ACCESS_ONCE(chan->enabled)))
+       if (unlikely(!READ_ONCE(chan->enabled)))
                return 0;
-       if (unlikely(!ACCESS_ONCE(event->enabled)))
+       if (unlikely(!READ_ONCE(event->enabled)))
                return 0;
 
        payload.ip = (unsigned long) krpi->rp->kp.addr;
        payload.parent_ip = (unsigned long) krpi->ret_addr;
 
-       lib_ring_buffer_ctx_init(&ctx, chan->chan, event, sizeof(payload),
+       lib_ring_buffer_ctx_init(&ctx, chan->chan, &lttng_probe_ctx, sizeof(payload),
                                 lttng_alignof(payload), -1);
        ret = chan->ops->event_reserve(&ctx, event->id);
        if (ret < 0)
@@ -219,9 +224,9 @@ int lttng_kretprobes_register(const char *name,
         * unregistered. Same for memory allocation.
         */
        kref_init(&lttng_krp->kref_alloc);
-       kref_get(&lttng_krp->kref_alloc);       /* inc refcount to 2 */
+       kref_get(&lttng_krp->kref_alloc);       /* inc refcount to 2, no overflow. */
        kref_init(&lttng_krp->kref_register);
-       kref_get(&lttng_krp->kref_register);    /* inc refcount to 2 */
+       kref_get(&lttng_krp->kref_register);    /* inc refcount to 2, no overflow. */
 
        /*
         * Ensure the memory we just allocated don't trigger page faults.
@@ -285,6 +290,26 @@ void lttng_kretprobes_destroy_private(struct lttng_event *event)
 }
 EXPORT_SYMBOL_GPL(lttng_kretprobes_destroy_private);
 
+int lttng_kretprobes_event_enable_state(struct lttng_event *event,
+               int enable)
+{
+       struct lttng_event *event_return;
+       struct lttng_krp *lttng_krp;
+
+       if (event->instrumentation != LTTNG_KERNEL_KRETPROBE) {
+               return -EINVAL;
+       }
+       if (event->enabled == enable) {
+               return -EBUSY;
+       }
+       lttng_krp = event->u.kretprobe.lttng_krp;
+       event_return = lttng_krp->event[EVENT_RETURN];
+       WRITE_ONCE(event->enabled, enable);
+       WRITE_ONCE(event_return->enabled, enable);
+       return 0;
+}
+EXPORT_SYMBOL_GPL(lttng_kretprobes_event_enable_state);
+
 MODULE_LICENSE("GPL and additional rights");
 MODULE_AUTHOR("Mathieu Desnoyers");
 MODULE_DESCRIPTION("Linux Trace Toolkit Kretprobes Support");