Cleanup: Move all source files to src/

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

diff --git a/src/lttng-context-vppid.c b/src/lttng-context-vppid.c
new file mode 100644 (file)
index 0000000..8757eb2
--- /dev/null
+++ b/src/lttng-context-vppid.c
@@ -0,0 +1,118 @@
+/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
+ *
+ * lttng-context-vppid.c
+ *
+ * LTTng vPPID context.
+ *
+ * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/syscalls.h>
+#include <lttng/events.h>
+#include <ringbuffer/frontend_types.h>
+#include <wrapper/vmalloc.h>
+#include <lttng/tracer.h>
+
+static
+size_t vppid_get_size(size_t offset)
+{
+       size_t size = 0;
+
+       size += lib_ring_buffer_align(offset, lttng_alignof(pid_t));
+       size += sizeof(pid_t);
+       return size;
+}
+
+static
+void vppid_record(struct lttng_ctx_field *field,
+                 struct lib_ring_buffer_ctx *ctx,
+                 struct lttng_channel *chan)
+{
+       struct task_struct *parent;
+       pid_t vppid;
+
+       /*
+        * current nsproxy can be NULL when scheduled out of exit. pid_vnr uses
+        * the current thread nsproxy to perform the lookup.
+        */
+
+       /*
+        * TODO: when we eventually add RCU subsystem instrumentation,
+        * taking the rcu read lock here will trigger RCU tracing
+        * recursively. We should modify the kernel synchronization so
+        * it synchronizes both for RCU and RCU sched, and rely on
+        * rcu_read_lock_sched_notrace.
+        */
+
+       rcu_read_lock();
+       parent = rcu_dereference(current->real_parent);
+       if (!current->nsproxy)
+               vppid = 0;
+       else
+               vppid = task_tgid_vnr(parent);
+       rcu_read_unlock();
+       lib_ring_buffer_align_ctx(ctx, lttng_alignof(vppid));
+       chan->ops->event_write(ctx, &vppid, sizeof(vppid));
+}
+
+static
+void vppid_get_value(struct lttng_ctx_field *field,
+               struct lttng_probe_ctx *lttng_probe_ctx,
+               union lttng_ctx_value *value)
+{
+       struct task_struct *parent;
+       pid_t vppid;
+
+       /*
+        * current nsproxy can be NULL when scheduled out of exit. pid_vnr uses
+        * the current thread nsproxy to perform the lookup.
+        */
+
+       /*
+        * TODO: when we eventually add RCU subsystem instrumentation,
+        * taking the rcu read lock here will trigger RCU tracing
+        * recursively. We should modify the kernel synchronization so
+        * it synchronizes both for RCU and RCU sched, and rely on
+        * rcu_read_lock_sched_notrace.
+        */
+
+       rcu_read_lock();
+       parent = rcu_dereference(current->real_parent);
+       if (!current->nsproxy)
+               vppid = 0;
+       else
+               vppid = task_tgid_vnr(parent);
+       rcu_read_unlock();
+       value->s64 = vppid;
+}
+
+int lttng_add_vppid_to_ctx(struct lttng_ctx **ctx)
+{
+       struct lttng_ctx_field *field;
+
+       field = lttng_append_context(ctx);
+       if (!field)
+               return -ENOMEM;
+       if (lttng_find_context(*ctx, "vppid")) {
+               lttng_remove_context_field(ctx, field);
+               return -EEXIST;
+       }
+       field->event_field.name = "vppid";
+       field->event_field.type.atype = atype_integer;
+       field->event_field.type.u.integer.size = sizeof(pid_t) * CHAR_BIT;
+       field->event_field.type.u.integer.alignment = lttng_alignof(pid_t) * CHAR_BIT;
+       field->event_field.type.u.integer.signedness = lttng_is_signed_type(pid_t);
+       field->event_field.type.u.integer.reverse_byte_order = 0;
+       field->event_field.type.u.integer.base = 10;
+       field->event_field.type.u.integer.encoding = lttng_encode_none;
+       field->get_size = vppid_get_size;
+       field->record = vppid_record;
+       field->get_value = vppid_get_value;
+       lttng_context_update(*ctx);
+       wrapper_vmalloc_sync_mappings();
+       return 0;
+}
+EXPORT_SYMBOL_GPL(lttng_add_vppid_to_ctx);