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
   9 #include <linux/module.h>
  10 #include <linux/list.h>
  11 #include <linux/mutex.h>
  12 #include <linux/slab.h>
  13 #include "wrapper/vmalloc.h"    /* for wrapper_vmalloc_sync_all() */
  14 #include "ltt-events.h"
  15 #include "ltt-tracer.h"
  16
  17 struct lttng_ctx_field *lttng_append_context(struct lttng_ctx **ctx_p)
  18 {
  19         struct lttng_ctx_field *field;
  20         struct lttng_ctx *ctx;
  21
  22         if (!*ctx_p) {
  23                 *ctx_p = kzalloc(sizeof(struct lttng_ctx), GFP_KERNEL);
  24                 if (!*ctx_p)
  25                         return NULL;
  26         }
  27         ctx = *ctx_p;
  28         if (ctx->nr_fields + 1 > ctx->allocated_fields) {
  29                 struct lttng_ctx_field *new_fields;
  30
  31                 ctx->allocated_fields = max_t(size_t, 1, 2 * ctx->allocated_fields);
  32                 new_fields = kzalloc(ctx->allocated_fields * sizeof(struct lttng_ctx_field), GFP_KERNEL);
  33                 if (!new_fields)
  34                         return NULL;
  35                 if (ctx->fields)
  36                         memcpy(new_fields, ctx->fields, sizeof(*ctx->fields) * ctx->nr_fields);
  37                 kfree(ctx->fields);
  38                 ctx->fields = new_fields;
  39         }
  40         field = &ctx->fields[ctx->nr_fields];
  41         ctx->nr_fields++;
  42         return field;
  43 }
  44 EXPORT_SYMBOL_GPL(lttng_append_context);
  45
  46 void lttng_destroy_context(struct lttng_ctx *ctx)
  47 {
  48         int i;
  49
  50         if (!ctx)
  51                 return;
  52         for (i = 0; i < ctx->nr_fields; i++) {
  53                 if (ctx->fields[i].destroy)
  54                         ctx->fields[i].destroy(&ctx->fields[i]);
  55         }
  56         kfree(ctx->fields);
  57         kfree(ctx);
  58 }