lttng-context.c

   1 /*
   2  * lttng-context.c
   3  *
   4  * LTTng trace/channel/event context management.
   5  *
   6  * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/list.h>
  25 #include <linux/mutex.h>
  26 #include <linux/slab.h>
  27 #include "wrapper/vmalloc.h"    /* for wrapper_vmalloc_sync_all() */
  28 #include "lttng-events.h"
  29 #include "lttng-tracer.h"
  30
  31 /*
  32  * The filter implementation requires that two consecutive "get" for the
  33  * same context performed by the same thread return the same result.
  34  */
  35
  36 /*
  37  * Static array of contexts, for $ctx filters.
  38  */
  39 struct lttng_ctx *lttng_static_ctx;
  40
  41 int lttng_find_context(struct lttng_ctx *ctx, const char *name)
  42 {
  43         unsigned int i;
  44
  45         for (i = 0; i < ctx->nr_fields; i++) {
  46                 /* Skip allocated (but non-initialized) contexts */
  47                 if (!ctx->fields[i].event_field.name)
  48                         continue;
  49                 if (!strcmp(ctx->fields[i].event_field.name, name))
  50                         return 1;
  51         }
  52         return 0;
  53 }
  54 EXPORT_SYMBOL_GPL(lttng_find_context);
  55
  56 int lttng_get_context_index(struct lttng_ctx *ctx, const char *name)
  57 {
  58         unsigned int i;
  59
  60         if (!ctx)
  61                 return -1;
  62         for (i = 0; i < ctx->nr_fields; i++) {
  63                 /* Skip allocated (but non-initialized) contexts */
  64                 if (!ctx->fields[i].event_field.name)
  65                         continue;
  66                 if (!strcmp(ctx->fields[i].event_field.name, name))
  67                         return i;
  68         }
  69         return -1;
  70 }
  71 EXPORT_SYMBOL_GPL(lttng_get_context_index);
  72
  73 /*
  74  * Note: as we append context information, the pointer location may change.
  75  */
  76 struct lttng_ctx_field *lttng_append_context(struct lttng_ctx **ctx_p)
  77 {
  78         struct lttng_ctx_field *field;
  79         struct lttng_ctx *ctx;
  80
  81         if (!*ctx_p) {
  82                 *ctx_p = kzalloc(sizeof(struct lttng_ctx), GFP_KERNEL);
  83                 if (!*ctx_p)
  84                         return NULL;
  85                 (*ctx_p)->largest_align = 1;
  86         }
  87         ctx = *ctx_p;
  88         if (ctx->nr_fields + 1 > ctx->allocated_fields) {
  89                 struct lttng_ctx_field *new_fields;
  90
  91                 ctx->allocated_fields = max_t(size_t, 1, 2 * ctx->allocated_fields);
  92                 new_fields = kzalloc(ctx->allocated_fields * sizeof(struct lttng_ctx_field), GFP_KERNEL);
  93                 if (!new_fields)
  94                         return NULL;
  95                 if (ctx->fields)
  96                         memcpy(new_fields, ctx->fields, sizeof(*ctx->fields) * ctx->nr_fields);
  97                 kfree(ctx->fields);
  98                 ctx->fields = new_fields;
  99         }
 100         field = &ctx->fields[ctx->nr_fields];
 101         ctx->nr_fields++;
 102         return field;
 103 }
 104 EXPORT_SYMBOL_GPL(lttng_append_context);
 105
 106 /*
 107  * lttng_context_update() should be called at least once between context
 108  * modification and trace start.
 109  */
 110 void lttng_context_update(struct lttng_ctx *ctx)
 111 {
 112         int i;
 113         size_t largest_align = 8;       /* in bits */
 114
 115         for (i = 0; i < ctx->nr_fields; i++) {
 116                 struct lttng_type *type;
 117                 size_t field_align = 8;
 118
 119                 type = &ctx->fields[i].event_field.type;
 120                 switch (type->atype) {
 121                 case atype_integer:
 122                         field_align = type->u.basic.integer.alignment;
 123                         break;
 124                 case atype_array:
 125                 {
 126                         struct lttng_basic_type *btype;
 127
 128                         btype = &type->u.array.elem_type;
 129                         switch (btype->atype) {
 130                         case atype_integer:
 131                                 field_align = btype->u.basic.integer.alignment;
 132                                 break;
 133                         case atype_string:
 134                                 break;
 135
 136                         case atype_array:
 137                         case atype_sequence:
 138                         default:
 139                                 WARN_ON_ONCE(1);
 140                                 break;
 141                         }
 142                         break;
 143                 }
 144                 case atype_sequence:
 145                 {
 146                         struct lttng_basic_type *btype;
 147
 148                         btype = &type->u.sequence.length_type;
 149                         switch (btype->atype) {
 150                         case atype_integer:
 151                                 field_align = btype->u.basic.integer.alignment;
 152                                 break;
 153
 154                         case atype_string:
 155                         case atype_array:
 156                         case atype_sequence:
 157                         default:
 158                                 WARN_ON_ONCE(1);
 159                                 break;
 160                         }
 161
 162                         btype = &type->u.sequence.elem_type;
 163                         switch (btype->atype) {
 164                         case atype_integer:
 165                                 field_align = max_t(size_t,
 166                                         field_align,
 167                                         btype->u.basic.integer.alignment);
 168                                 break;
 169
 170                         case atype_string:
 171                                 break;
 172
 173                         case atype_array:
 174                         case atype_sequence:
 175                         default:
 176                                 WARN_ON_ONCE(1);
 177                                 break;
 178                         }
 179                         break;
 180                 }
 181                 case atype_string:
 182                         break;
 183
 184                 case atype_enum:
 185                 default:
 186                         WARN_ON_ONCE(1);
 187                         break;
 188                 }
 189                 largest_align = max_t(size_t, largest_align, field_align);
 190         }
 191         ctx->largest_align = largest_align >> 3;        /* bits to bytes */
 192 }
 193
 194 /*
 195  * Remove last context field.
 196  */
 197 void lttng_remove_context_field(struct lttng_ctx **ctx_p,
 198                                 struct lttng_ctx_field *field)
 199 {
 200         struct lttng_ctx *ctx;
 201
 202         ctx = *ctx_p;
 203         ctx->nr_fields--;
 204         WARN_ON_ONCE(&ctx->fields[ctx->nr_fields] != field);
 205         memset(&ctx->fields[ctx->nr_fields], 0, sizeof(struct lttng_ctx_field));
 206 }
 207 EXPORT_SYMBOL_GPL(lttng_remove_context_field);
 208
 209 void lttng_destroy_context(struct lttng_ctx *ctx)
 210 {
 211         int i;
 212
 213         if (!ctx)
 214                 return;
 215         for (i = 0; i < ctx->nr_fields; i++) {
 216                 if (ctx->fields[i].destroy)
 217                         ctx->fields[i].destroy(&ctx->fields[i]);
 218         }
 219         kfree(ctx->fields);
 220         kfree(ctx);
 221 }
 222
 223 int lttng_context_init(void)
 224 {
 225         int ret;
 226
 227         ret = lttng_add_hostname_to_ctx(&lttng_static_ctx);
 228         if (ret) {
 229                 printk(KERN_WARNING "Cannot add context lttng_add_procname_to_ctx");
 230         }
 231         ret = lttng_add_nice_to_ctx(&lttng_static_ctx);
 232         if (ret) {
 233                 printk(KERN_WARNING "Cannot add context lttng_add_procname_to_ctx");
 234         }
 235         ret = lttng_add_pid_to_ctx(&lttng_static_ctx);
 236         if (ret) {
 237                 printk(KERN_WARNING "Cannot add context lttng_add_pthread_id_to_ctx");
 238         }
 239         ret = lttng_add_ppid_to_ctx(&lttng_static_ctx);
 240         if (ret) {
 241                 printk(KERN_WARNING "Cannot add context lttng_add_procname_to_ctx");
 242         }
 243         ret = lttng_add_prio_to_ctx(&lttng_static_ctx);
 244         if (ret) {
 245                 printk(KERN_WARNING "Cannot add context lttng_add_vpid_to_ctx");
 246         }
 247         ret = lttng_add_procname_to_ctx(&lttng_static_ctx);
 248         if (ret) {
 249                 printk(KERN_WARNING "Cannot add context lttng_add_vtid_to_ctx");
 250         }
 251         ret = lttng_add_tid_to_ctx(&lttng_static_ctx);
 252         if (ret) {
 253                 printk(KERN_WARNING "Cannot add context lttng_add_procname_to_ctx");
 254         }
 255         ret = lttng_add_vppid_to_ctx(&lttng_static_ctx);
 256         if (ret) {
 257                 printk(KERN_WARNING "Cannot add context lttng_add_procname_to_ctx");
 258         }
 259         ret = lttng_add_vtid_to_ctx(&lttng_static_ctx);
 260         if (ret) {
 261                 printk(KERN_WARNING "Cannot add context lttng_add_procname_to_ctx");
 262         }
 263         ret = lttng_add_vpid_to_ctx(&lttng_static_ctx);
 264         if (ret) {
 265                 printk(KERN_WARNING "Cannot add context lttng_add_procname_to_ctx");
 266         }
 267         /* TODO: perf counters for filtering */
 268         return 0;
 269 }
 270
 271 void lttng_context_exit(void)
 272 {
 273         lttng_destroy_context(lttng_static_ctx);
 274         lttng_static_ctx = NULL;
 275 }