Version 2.13.11

[lttng-modules.git] / src / lttng-context-prio.c

diff --git a/src/lttng-context-prio.c b/src/lttng-context-prio.c
index aac10a6399ac8618a42e23c299edd8d41a0c7ee7..8cb025cd9cac08e763c27dd2d2017d04d4201ad0 100644 (file)
--- a/src/lttng-context-prio.c
+++ b/src/lttng-context-prio.c
@@ -14,34 +14,28 @@
 #include <lttng/events-internal.h>
 #include <ringbuffer/frontend_types.h>
 #include <wrapper/vmalloc.h>
-#include <wrapper/kallsyms.h>
 #include <lttng/tracer.h>
+#include <lttng/kernel-version.h>
 
-static
-int (*wrapper_task_prio_sym)(struct task_struct *t);
-
-int wrapper_task_prio_init(void)
-{
-       wrapper_task_prio_sym = (void *) kallsyms_lookup_funcptr("task_prio");
-       if (!wrapper_task_prio_sym) {
-               printk(KERN_WARNING "LTTng: task_prio symbol lookup failed.\n");
-               return -EINVAL;
-       }
-       return 0;
-}
-EXPORT_SYMBOL_GPL(wrapper_task_prio_init);
+/*
+ * From kernel v3.0 to v3.8, MAX_RT_PRIO is defined in linux/sched.h.
+ * From kernel v3.9 to v3.14, MAX_RT_PRIO is defined in linux/sched/rt.h,
+ * which is not included by linux/sched.h (hence this work-around).
+ * From kernel v3.15 onwards, MAX_RT_PRIO is defined in linux/sched/prio.h,
+ * which is included by linux/sched.h.
+ */
+#if LTTNG_KERNEL_RANGE(3,9,0, 3,15,0)
+# include <linux/sched/rt.h>
+#endif
 
 /*
- * Canary function to check for 'task_prio()' at compile time.
- *
- * From 'include/linux/sched.h':
- *
- *   extern int task_prio(const struct task_struct *p);
+ * task_prio() has been implemented as p->prio - MAX_RT_PRIO since at
+ * least kernel v3.0.
  */
-__attribute__((unused)) static
-int __canary__task_prio(const struct task_struct *p)
+static
+int wrapper_task_prio(struct task_struct *p)
 {
-       return task_prio(p);
+       return p->prio - MAX_RT_PRIO;
 }
 
 static
@@ -61,7 +55,7 @@ void prio_record(void *priv, struct lttng_kernel_probe_ctx *probe_ctx,
 {
        int prio;
 
-       prio = wrapper_task_prio_sym(current);
+       prio = wrapper_task_prio(current);
        chan->ops->event_write(ctx, &prio, sizeof(prio), lttng_alignof(prio));
 }
 
@@ -70,7 +64,7 @@ void prio_get_value(void *priv,
                struct lttng_kernel_probe_ctx *lttng_probe_ctx,
                struct lttng_ctx_value *value)
 {
-       value->u.s64 = wrapper_task_prio_sym(current);
+       value->u.s64 = wrapper_task_prio(current);
 }
 
 static const struct lttng_kernel_ctx_field *ctx_field = lttng_kernel_static_ctx_field(