lttng-context-vppid.c

   1 /*
   2  * (C) Copyright        2009-2011 -
   3  *              Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * LTTng vPPID context.
   6  *
   7  * Dual LGPL v2.1/GPL v2 license.
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/slab.h>
  12 #include <linux/sched.h>
  13 #include <linux/syscalls.h>
  14 #include "lttng-events.h"
  15 #include "wrapper/ringbuffer/frontend_types.h"
  16 #include "wrapper/vmalloc.h"
  17 #include "lttng-tracer.h"
  18
  19 static
  20 size_t vppid_get_size(size_t offset)
  21 {
  22         size_t size = 0;
  23
  24         size += lib_ring_buffer_align(offset, lttng_alignof(pid_t));
  25         size += sizeof(pid_t);
  26         return size;
  27 }
  28
  29 static
  30 void vppid_record(struct lttng_ctx_field *field,
  31                   struct lib_ring_buffer_ctx *ctx,
  32                   struct lttng_channel *chan)
  33 {
  34         struct task_struct *parent;
  35         pid_t vppid;
  36
  37         /*
  38          * nsproxy can be NULL when scheduled out of exit.
  39          */
  40         rcu_read_lock();
  41         parent = rcu_dereference(current->real_parent);
  42         if (!parent->nsproxy)
  43                 vppid = 0;
  44         else
  45                 vppid = task_tgid_vnr(parent);
  46         rcu_read_unlock();
  47         lib_ring_buffer_align_ctx(ctx, lttng_alignof(vppid));
  48         chan->ops->event_write(ctx, &vppid, sizeof(vppid));
  49 }
  50
  51 int lttng_add_vppid_to_ctx(struct lttng_ctx **ctx)
  52 {
  53         struct lttng_ctx_field *field;
  54
  55         field = lttng_append_context(ctx);
  56         if (!field)
  57                 return -ENOMEM;
  58         if (lttng_find_context(*ctx, "vppid")) {
  59                 lttng_remove_context_field(ctx, field);
  60                 return -EEXIST;
  61         }
  62         field->event_field.name = "vppid";
  63         field->event_field.type.atype = atype_integer;
  64         field->event_field.type.u.basic.integer.size = sizeof(pid_t) * CHAR_BIT;
  65         field->event_field.type.u.basic.integer.alignment = lttng_alignof(pid_t) * CHAR_BIT;
  66         field->event_field.type.u.basic.integer.signedness = is_signed_type(pid_t);
  67         field->event_field.type.u.basic.integer.reverse_byte_order = 0;
  68         field->event_field.type.u.basic.integer.base = 10;
  69         field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
  70         field->get_size = vppid_get_size;
  71         field->record = vppid_record;
  72         wrapper_vmalloc_sync_all();
  73         return 0;
  74 }
  75 EXPORT_SYMBOL_GPL(lttng_add_vppid_to_ctx);
  76
  77 MODULE_LICENSE("GPL and additional rights");
  78 MODULE_AUTHOR("Mathieu Desnoyers");
  79 MODULE_DESCRIPTION("Linux Trace Toolkit vPPID Context");