ltt-context.c

   1 /*
   2  * ltt-context.c
   3  *
   4  * Copyright 2011 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * LTTng trace/channel/event context management.
   7  *
   8  * Dual LGPL v2.1/GPL v2 license.
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/list.h>
  13 #include <linux/mutex.h>
  14 #include <linux/slab.h>
  15 #include "wrapper/vmalloc.h"    /* for wrapper_vmalloc_sync_all() */
  16 #include "ltt-events.h"
  17 #include "ltt-tracer.h"
  18
  19 int lttng_find_context(struct lttng_ctx *ctx, const char *name)
  20 {
  21         unsigned int i;
  22
  23         for (i = 0; i < ctx->nr_fields; i++) {
  24                 if (!strcmp(ctx->fields[i].event_field.name, name))
  25                         return 1;
  26         }
  27         return 0;
  28 }
  29 EXPORT_SYMBOL_GPL(lttng_find_context);
  30
  31 struct lttng_ctx_field *lttng_append_context(struct lttng_ctx **ctx_p)
  32 {
  33         struct lttng_ctx_field *field;
  34         struct lttng_ctx *ctx;
  35
  36         if (!*ctx_p) {
  37                 *ctx_p = kzalloc(sizeof(struct lttng_ctx), GFP_KERNEL);
  38                 if (!*ctx_p)
  39                         return NULL;
  40         }
  41         ctx = *ctx_p;
  42         if (ctx->nr_fields + 1 > ctx->allocated_fields) {
  43                 struct lttng_ctx_field *new_fields;
  44
  45                 ctx->allocated_fields = max_t(size_t, 1, 2 * ctx->allocated_fields);
  46                 new_fields = kzalloc(ctx->allocated_fields * sizeof(struct lttng_ctx_field), GFP_KERNEL);
  47                 if (!new_fields)
  48                         return NULL;
  49                 if (ctx->fields)
  50                         memcpy(new_fields, ctx->fields, sizeof(*ctx->fields) * ctx->nr_fields);
  51                 kfree(ctx->fields);
  52                 ctx->fields = new_fields;
  53         }
  54         field = &ctx->fields[ctx->nr_fields];
  55         ctx->nr_fields++;
  56         return field;
  57 }
  58 EXPORT_SYMBOL_GPL(lttng_append_context);
  59
  60 void lttng_remove_context_field(struct lttng_ctx **ctx_p,
  61                                 struct lttng_ctx_field *field)
  62 {
  63         struct lttng_ctx *ctx;
  64
  65         ctx = *ctx_p;
  66         ctx->nr_fields--;
  67         memset(&ctx->fields[ctx->nr_fields], 0, sizeof(struct lttng_ctx_field));
  68 }
  69 EXPORT_SYMBOL_GPL(lttng_remove_context_field);
  70
  71 void lttng_destroy_context(struct lttng_ctx *ctx)
  72 {
  73         int i;
  74
  75         if (!ctx)
  76                 return;
  77         for (i = 0; i < ctx->nr_fields; i++) {
  78                 if (ctx->fields[i].destroy)
  79                         ctx->fields[i].destroy(&ctx->fields[i]);
  80         }
  81         kfree(ctx->fields);
  82         kfree(ctx);
  83 }