libust/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 struct lttng_ctx_field *lttng_append_context(struct lttng_ctx **ctx_p)
  20 {
  21         struct lttng_ctx_field *field;
  22         struct lttng_ctx *ctx;
  23
  24         if (!*ctx_p) {
  25                 *ctx_p = kzalloc(sizeof(struct lttng_ctx), GFP_KERNEL);
  26                 if (!*ctx_p)
  27                         return NULL;
  28         }
  29         ctx = *ctx_p;
  30         if (ctx->nr_fields + 1 > ctx->allocated_fields) {
  31                 struct lttng_ctx_field *new_fields;
  32
  33                 ctx->allocated_fields = max_t(size_t, 1, 2 * ctx->allocated_fields);
  34                 new_fields = kzalloc(ctx->allocated_fields * sizeof(struct lttng_ctx_field), GFP_KERNEL);
  35                 if (!new_fields)
  36                         return NULL;
  37                 if (ctx->fields)
  38                         memcpy(new_fields, ctx->fields, sizeof(*ctx->fields) * ctx->nr_fields);
  39                 kfree(ctx->fields);
  40                 ctx->fields = new_fields;
  41         }
  42         field = &ctx->fields[ctx->nr_fields];
  43         ctx->nr_fields++;
  44         return field;
  45 }
  46 EXPORT_SYMBOL_GPL(lttng_append_context);
  47
  48 /*
  49  * Remove last context field.
  50  */
  51 void lttng_remove_context_field(struct lttng_ctx **ctx_p,
  52                                 struct lttng_ctx_field *field)
  53 {
  54         struct lttng_ctx *ctx;
  55
  56         ctx = *ctx_p;
  57         ctx->nr_fields--;
  58         WARN_ON_ONCE(&ctx->fields[ctx->nr_fields] != field);
  59         memset(&ctx->fields[ctx->nr_fields], 0, sizeof(struct lttng_ctx_field));
  60 }
  61 EXPORT_SYMBOL_GPL(lttng_remove_context_field);
  62
  63 void lttng_destroy_context(struct lttng_ctx *ctx)
  64 {
  65         int i;
  66
  67         if (!ctx)
  68                 return;
  69         for (i = 0; i < ctx->nr_fields; i++) {
  70                 if (ctx->fields[i].destroy)
  71                         ctx->fields[i].destroy(&ctx->fields[i]);
  72         }
  73         kfree(ctx->fields);
  74         kfree(ctx);
  75 }