lttng-context-vtid.c

   1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
   2  *
   3  * lttng-context-vtid.c
   4  *
   5  * LTTng vTID context.
   6  *
   7  * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/slab.h>
  12 #include <linux/sched.h>
  13 #include <lttng/lttng-events.h>
  14 #include <ringbuffer/frontend_types.h>
  15 #include <lttng/lttng-tracer.h>
  16
  17 static
  18 size_t vtid_get_size(size_t offset)
  19 {
  20         size_t size = 0;
  21
  22         size += lib_ring_buffer_align(offset, lttng_alignof(pid_t));
  23         size += sizeof(pid_t);
  24         return size;
  25 }
  26
  27 static
  28 void vtid_record(struct lttng_ctx_field *field,
  29                  struct lib_ring_buffer_ctx *ctx,
  30                  struct lttng_channel *chan)
  31 {
  32         pid_t vtid;
  33
  34         /*
  35          * nsproxy can be NULL when scheduled out of exit.
  36          */
  37         if (!current->nsproxy)
  38                 vtid = 0;
  39         else
  40                 vtid = task_pid_vnr(current);
  41         lib_ring_buffer_align_ctx(ctx, lttng_alignof(vtid));
  42         chan->ops->event_write(ctx, &vtid, sizeof(vtid));
  43 }
  44
  45 static
  46 void vtid_get_value(struct lttng_ctx_field *field,
  47                 struct lttng_probe_ctx *lttng_probe_ctx,
  48                 union lttng_ctx_value *value)
  49 {
  50         pid_t vtid;
  51
  52         /*
  53          * nsproxy can be NULL when scheduled out of exit.
  54          */
  55         if (!current->nsproxy)
  56                 vtid = 0;
  57         else
  58                 vtid = task_pid_vnr(current);
  59         value->s64 = vtid;
  60 }
  61
  62 int lttng_add_vtid_to_ctx(struct lttng_ctx **ctx)
  63 {
  64         struct lttng_ctx_field *field;
  65
  66         field = lttng_append_context(ctx);
  67         if (!field)
  68                 return -ENOMEM;
  69         if (lttng_find_context(*ctx, "vtid")) {
  70                 lttng_remove_context_field(ctx, field);
  71                 return -EEXIST;
  72         }
  73         field->event_field.name = "vtid";
  74         field->event_field.type.atype = atype_integer;
  75         field->event_field.type.u.integer.size = sizeof(pid_t) * CHAR_BIT;
  76         field->event_field.type.u.integer.alignment = lttng_alignof(pid_t) * CHAR_BIT;
  77         field->event_field.type.u.integer.signedness = lttng_is_signed_type(pid_t);
  78         field->event_field.type.u.integer.reverse_byte_order = 0;
  79         field->event_field.type.u.integer.base = 10;
  80         field->event_field.type.u.integer.encoding = lttng_encode_none;
  81         field->get_size = vtid_get_size;
  82         field->record = vtid_record;
  83         field->get_value = vtid_get_value;
  84         lttng_context_update(*ctx);
  85         return 0;
  86 }
  87 EXPORT_SYMBOL_GPL(lttng_add_vtid_to_ctx);