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                 /* Skip allocated (but non-initialized) contexts */
  25                 if (!ctx->fields[i].event_field.name)
  26                         continue;
  27                 if (!strcmp(ctx->fields[i].event_field.name, name))
  28                         return 1;
  29         }
  30         return 0;
  31 }
  32 EXPORT_SYMBOL_GPL(lttng_find_context);
  33
  34 struct lttng_ctx_field *lttng_append_context(struct lttng_ctx **ctx_p)
  35 {
  36         struct lttng_ctx_field *field;
  37         struct lttng_ctx *ctx;
  38
  39         if (!*ctx_p) {
  40                 *ctx_p = kzalloc(sizeof(struct lttng_ctx), GFP_KERNEL);
  41                 if (!*ctx_p)
  42                         return NULL;
  43         }
  44         ctx = *ctx_p;
  45         if (ctx->nr_fields + 1 > ctx->allocated_fields) {
  46                 struct lttng_ctx_field *new_fields;
  47
  48                 ctx->allocated_fields = max_t(size_t, 1, 2 * ctx->allocated_fields);
  49                 new_fields = kzalloc(ctx->allocated_fields * sizeof(struct lttng_ctx_field), GFP_KERNEL);
  50                 if (!new_fields)
  51                         return NULL;
  52                 if (ctx->fields)
  53                         memcpy(new_fields, ctx->fields, sizeof(*ctx->fields) * ctx->nr_fields);
  54                 kfree(ctx->fields);
  55                 ctx->fields = new_fields;
  56         }
  57         field = &ctx->fields[ctx->nr_fields];
  58         ctx->nr_fields++;
  59         return field;
  60 }
  61 EXPORT_SYMBOL_GPL(lttng_append_context);
  62
  63 /*
  64  * Remove last context field.
  65  */
  66 void lttng_remove_context_field(struct lttng_ctx **ctx_p,
  67                                 struct lttng_ctx_field *field)
  68 {
  69         struct lttng_ctx *ctx;
  70
  71         ctx = *ctx_p;
  72         ctx->nr_fields--;
  73         WARN_ON_ONCE(&ctx->fields[ctx->nr_fields] != field);
  74         memset(&ctx->fields[ctx->nr_fields], 0, sizeof(struct lttng_ctx_field));
  75 }
  76 EXPORT_SYMBOL_GPL(lttng_remove_context_field);
  77
  78 void lttng_destroy_context(struct lttng_ctx *ctx)
  79 {
  80         int i;
  81
  82         if (!ctx)
  83                 return;
  84         for (i = 0; i < ctx->nr_fields; i++) {
  85                 if (ctx->fields[i].destroy)
  86                         ctx->fields[i].destroy(&ctx->fields[i]);
  87         }
  88         kfree(ctx->fields);
  89         kfree(ctx);
  90 }