lttng-statedump-impl.c

   1 /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
   2  *
   3  * lttng-statedump.c
   4  *
   5  * Linux Trace Toolkit Next Generation Kernel State Dump
   6  *
   7  * Copyright 2005 Jean-Hugues Deschenes <jean-hugues.deschenes@polymtl.ca>
   8  * Copyright 2006-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   9  *
  10  * Changes:
  11  *      Eric Clement:                   Add listing of network IP interface
  12  *      2006, 2007 Mathieu Desnoyers    Fix kernel threads
  13  *                                      Various updates
  14  */
  15
  16 #include <linux/init.h>
  17 #include <linux/module.h>
  18 #include <linux/netlink.h>
  19 #include <linux/inet.h>
  20 #include <linux/ip.h>
  21 #include <linux/kthread.h>
  22 #include <linux/proc_fs.h>
  23 #include <linux/file.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/irqnr.h>
  26 #include <linux/cpu.h>
  27 #include <linux/netdevice.h>
  28 #include <linux/inetdevice.h>
  29 #include <linux/sched.h>
  30 #include <linux/mm.h>
  31 #include <linux/swap.h>
  32 #include <linux/wait.h>
  33 #include <linux/mutex.h>
  34 #include <linux/device.h>
  35
  36 #include <lttng-events.h>
  37 #include <lttng-tracer.h>
  38 #include <wrapper/irqdesc.h>
  39 #include <wrapper/fdtable.h>
  40 #include <wrapper/namespace.h>
  41 #include <wrapper/irq.h>
  42 #include <wrapper/tracepoint.h>
  43 #include <wrapper/genhd.h>
  44 #include <wrapper/file.h>
  45 #include <wrapper/fdtable.h>
  46
  47 #ifdef CONFIG_LTTNG_HAS_LIST_IRQ
  48 #include <linux/irq.h>
  49 #endif
  50
  51 /* Define the tracepoints, but do not build the probes */
  52 #define CREATE_TRACE_POINTS
  53 #define TRACE_INCLUDE_PATH instrumentation/events/lttng-module
  54 #define TRACE_INCLUDE_FILE lttng-statedump
  55 #define LTTNG_INSTRUMENTATION
  56 #include <instrumentation/events/lttng-module/lttng-statedump.h>
  57
  58 LTTNG_DEFINE_TRACE(lttng_statedump_block_device,
  59         TP_PROTO(struct lttng_session *session,
  60                 dev_t dev, const char *diskname),
  61         TP_ARGS(session, dev, diskname));
  62
  63 LTTNG_DEFINE_TRACE(lttng_statedump_end,
  64         TP_PROTO(struct lttng_session *session),
  65         TP_ARGS(session));
  66
  67 LTTNG_DEFINE_TRACE(lttng_statedump_interrupt,
  68         TP_PROTO(struct lttng_session *session,
  69                 unsigned int irq, const char *chip_name,
  70                 struct irqaction *action),
  71         TP_ARGS(session, irq, chip_name, action));
  72
  73 LTTNG_DEFINE_TRACE(lttng_statedump_file_descriptor,
  74         TP_PROTO(struct lttng_session *session,
  75                 struct files_struct *files,
  76                 int fd, const char *filename,
  77                 unsigned int flags, fmode_t fmode),
  78         TP_ARGS(session, files, fd, filename, flags, fmode));
  79
  80 LTTNG_DEFINE_TRACE(lttng_statedump_start,
  81         TP_PROTO(struct lttng_session *session),
  82         TP_ARGS(session));
  83
  84 LTTNG_DEFINE_TRACE(lttng_statedump_process_state,
  85         TP_PROTO(struct lttng_session *session,
  86                 struct task_struct *p,
  87                 int type, int mode, int submode, int status,
  88                 struct files_struct *files),
  89         TP_ARGS(session, p, type, mode, submode, status, files));
  90
  91 LTTNG_DEFINE_TRACE(lttng_statedump_process_pid_ns,
  92         TP_PROTO(struct lttng_session *session,
  93                 struct task_struct *p,
  94                 struct pid_namespace *pid_ns),
  95         TP_ARGS(session, p, pid_ns));
  96
  97 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,6,0))
  98 LTTNG_DEFINE_TRACE(lttng_statedump_process_cgroup_ns,
  99         TP_PROTO(struct lttng_session *session,
 100                 struct task_struct *p,
 101                 struct cgroup_namespace *cgroup_ns),
 102         TP_ARGS(session, p, cgroup_ns));
 103 #endif
 104
 105 LTTNG_DEFINE_TRACE(lttng_statedump_process_ipc_ns,
 106         TP_PROTO(struct lttng_session *session,
 107                 struct task_struct *p,
 108                 struct ipc_namespace *ipc_ns),
 109         TP_ARGS(session, p, ipc_ns));
 110
 111 #ifndef LTTNG_MNT_NS_MISSING_HEADER
 112 LTTNG_DEFINE_TRACE(lttng_statedump_process_mnt_ns,
 113         TP_PROTO(struct lttng_session *session,
 114                 struct task_struct *p,
 115                 struct mnt_namespace *mnt_ns),
 116         TP_ARGS(session, p, mnt_ns));
 117 #endif
 118
 119 LTTNG_DEFINE_TRACE(lttng_statedump_process_net_ns,
 120         TP_PROTO(struct lttng_session *session,
 121                 struct task_struct *p,
 122                 struct net *net_ns),
 123         TP_ARGS(session, p, net_ns));
 124
 125 LTTNG_DEFINE_TRACE(lttng_statedump_process_user_ns,
 126         TP_PROTO(struct lttng_session *session,
 127                 struct task_struct *p,
 128                 struct user_namespace *user_ns),
 129         TP_ARGS(session, p, user_ns));
 130
 131 LTTNG_DEFINE_TRACE(lttng_statedump_process_uts_ns,
 132         TP_PROTO(struct lttng_session *session,
 133                 struct task_struct *p,
 134                 struct uts_namespace *uts_ns),
 135         TP_ARGS(session, p, uts_ns));
 136
 137 LTTNG_DEFINE_TRACE(lttng_statedump_network_interface,
 138         TP_PROTO(struct lttng_session *session,
 139                 struct net_device *dev, struct in_ifaddr *ifa),
 140         TP_ARGS(session, dev, ifa));
 141
 142 #ifdef LTTNG_HAVE_STATEDUMP_CPU_TOPOLOGY
 143 LTTNG_DEFINE_TRACE(lttng_statedump_cpu_topology,
 144         TP_PROTO(struct lttng_session *session, struct cpuinfo_x86 *c),
 145         TP_ARGS(session, c));
 146 #endif
 147
 148 struct lttng_fd_ctx {
 149         char *page;
 150         struct lttng_session *session;
 151         struct files_struct *files;
 152 };
 153
 154 /*
 155  * Protected by the trace lock.
 156  */
 157 static struct delayed_work cpu_work[NR_CPUS];
 158 static DECLARE_WAIT_QUEUE_HEAD(statedump_wq);
 159 static atomic_t kernel_threads_to_run;
 160
 161 enum lttng_thread_type {
 162         LTTNG_USER_THREAD = 0,
 163         LTTNG_KERNEL_THREAD = 1,
 164 };
 165
 166 enum lttng_execution_mode {
 167         LTTNG_USER_MODE = 0,
 168         LTTNG_SYSCALL = 1,
 169         LTTNG_TRAP = 2,
 170         LTTNG_IRQ = 3,
 171         LTTNG_SOFTIRQ = 4,
 172         LTTNG_MODE_UNKNOWN = 5,
 173 };
 174
 175 enum lttng_execution_submode {
 176         LTTNG_NONE = 0,
 177         LTTNG_UNKNOWN = 1,
 178 };
 179
 180 enum lttng_process_status {
 181         LTTNG_UNNAMED = 0,
 182         LTTNG_WAIT_FORK = 1,
 183         LTTNG_WAIT_CPU = 2,
 184         LTTNG_EXIT = 3,
 185         LTTNG_ZOMBIE = 4,
 186         LTTNG_WAIT = 5,
 187         LTTNG_RUN = 6,
 188         LTTNG_DEAD = 7,
 189 };
 190
 191
 192 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,11,0))
 193
 194 #define LTTNG_PART_STRUCT_TYPE struct block_device
 195
 196 static
 197 int lttng_get_part_name(struct gendisk *disk, struct block_device *part, char *name_buf)
 198 {
 199         const char *p;
 200
 201         p = bdevname(part, name_buf);
 202         if (!p)
 203                 return -ENOSYS;
 204
 205         return 0;
 206 }
 207
 208 static
 209 dev_t lttng_get_part_devt(struct block_device *part)
 210 {
 211         return part->bd_dev;
 212 }
 213
 214 #else
 215
 216 #define LTTNG_PART_STRUCT_TYPE struct hd_struct
 217
 218 static
 219 int lttng_get_part_name(struct gendisk *disk, struct hd_struct *part, char *name_buf)
 220 {
 221         const char *p;
 222         struct block_device bdev;
 223
 224         /*
 225          * Create a partial 'struct blockdevice' to use
 226          * 'bdevname()' which is a simple wrapper over
 227          * 'disk_name()' but has the honor to be EXPORT_SYMBOL.
 228          */
 229         bdev.bd_disk = disk;
 230         bdev.bd_part = part;
 231
 232         p = bdevname(&bdev, name_buf);
 233         if (!p)
 234                 return -ENOSYS;
 235
 236         return 0;
 237 }
 238
 239 static
 240 dev_t lttng_get_part_devt(struct hd_struct *part)
 241 {
 242         return part_devt(part);
 243 }
 244 #endif
 245
 246 static
 247 int lttng_enumerate_block_devices(struct lttng_session *session)
 248 {
 249         struct class *ptr_block_class;
 250         struct device_type *ptr_disk_type;
 251         struct class_dev_iter iter;
 252         struct device *dev;
 253
 254         ptr_block_class = wrapper_get_block_class();
 255         if (!ptr_block_class)
 256                 return -ENOSYS;
 257         ptr_disk_type = wrapper_get_disk_type();
 258         if (!ptr_disk_type) {
 259                 return -ENOSYS;
 260         }
 261         class_dev_iter_init(&iter, ptr_block_class, NULL, ptr_disk_type);
 262         while ((dev = class_dev_iter_next(&iter))) {
 263                 struct disk_part_iter piter;
 264                 struct gendisk *disk = dev_to_disk(dev);
 265                 LTTNG_PART_STRUCT_TYPE *part;
 266
 267                 /*
 268                  * Don't show empty devices or things that have been
 269                  * suppressed
 270                  */
 271                 if (get_capacity(disk) == 0 ||
 272                     (disk->flags & GENHD_FL_SUPPRESS_PARTITION_INFO))
 273                         continue;
 274
 275                 disk_part_iter_init(&piter, disk, DISK_PITER_INCL_PART0);
 276                 while ((part = disk_part_iter_next(&piter))) {
 277                         char name_buf[BDEVNAME_SIZE];
 278
 279                         if (lttng_get_part_name(disk, part, name_buf) == -ENOSYS) {
 280                                 disk_part_iter_exit(&piter);
 281                                 class_dev_iter_exit(&iter);
 282                                 return -ENOSYS;
 283                         }
 284                         trace_lttng_statedump_block_device(session,
 285                                         lttng_get_part_devt(part), name_buf);
 286                 }
 287                 disk_part_iter_exit(&piter);
 288         }
 289         class_dev_iter_exit(&iter);
 290         return 0;
 291 }
 292
 293 #ifdef CONFIG_INET
 294
 295 static
 296 void lttng_enumerate_device(struct lttng_session *session,
 297                 struct net_device *dev)
 298 {
 299         struct in_device *in_dev;
 300         struct in_ifaddr *ifa;
 301
 302         if (dev->flags & IFF_UP) {
 303                 in_dev = in_dev_get(dev);
 304                 if (in_dev) {
 305                         for (ifa = in_dev->ifa_list; ifa != NULL;
 306                              ifa = ifa->ifa_next) {
 307                                 trace_lttng_statedump_network_interface(
 308                                         session, dev, ifa);
 309                         }
 310                         in_dev_put(in_dev);
 311                 }
 312         } else {
 313                 trace_lttng_statedump_network_interface(
 314                         session, dev, NULL);
 315         }
 316 }
 317
 318 static
 319 int lttng_enumerate_network_ip_interface(struct lttng_session *session)
 320 {
 321         struct net_device *dev;
 322
 323         read_lock(&dev_base_lock);
 324         for_each_netdev(&init_net, dev)
 325                 lttng_enumerate_device(session, dev);
 326         read_unlock(&dev_base_lock);
 327
 328         return 0;
 329 }
 330 #else /* CONFIG_INET */
 331 static inline
 332 int lttng_enumerate_network_ip_interface(struct lttng_session *session)
 333 {
 334         return 0;
 335 }
 336 #endif /* CONFIG_INET */
 337
 338 static
 339 int lttng_dump_one_fd(const void *p, struct file *file, unsigned int fd)
 340 {
 341         const struct lttng_fd_ctx *ctx = p;
 342         const char *s = d_path(&file->f_path, ctx->page, PAGE_SIZE);
 343         unsigned int flags = file->f_flags;
 344         struct fdtable *fdt;
 345
 346         /*
 347          * We don't expose kernel internal flags, only userspace-visible
 348          * flags.
 349          */
 350         flags &= ~FMODE_NONOTIFY;
 351         fdt = files_fdtable(ctx->files);
 352         /*
 353          * We need to check here again whether fd is within the fdt
 354          * max_fds range, because we might be seeing a different
 355          * files_fdtable() than iterate_fd(), assuming only RCU is
 356          * protecting the read. In reality, iterate_fd() holds
 357          * file_lock, which should ensure the fdt does not change while
 358          * the lock is taken, but we are not aware whether this is
 359          * guaranteed or not, so play safe.
 360          */
 361         if (fd < fdt->max_fds && lttng_close_on_exec(fd, fdt))
 362                 flags |= O_CLOEXEC;
 363         if (IS_ERR(s)) {
 364                 struct dentry *dentry = file->f_path.dentry;
 365
 366                 /* Make sure we give at least some info */
 367                 spin_lock(&dentry->d_lock);
 368                 trace_lttng_statedump_file_descriptor(ctx->session,
 369                         ctx->files, fd, dentry->d_name.name, flags,
 370                         file->f_mode);
 371                 spin_unlock(&dentry->d_lock);
 372                 goto end;
 373         }
 374         trace_lttng_statedump_file_descriptor(ctx->session,
 375                 ctx->files, fd, s, flags, file->f_mode);
 376 end:
 377         return 0;
 378 }
 379
 380 /* Called with task lock held. */
 381 static
 382 void lttng_enumerate_files(struct lttng_session *session,
 383                 struct files_struct *files,
 384                 char *tmp)
 385 {
 386         struct lttng_fd_ctx ctx = { .page = tmp, .session = session, .files = files, };
 387
 388         lttng_iterate_fd(files, 0, lttng_dump_one_fd, &ctx);
 389 }
 390
 391 #ifdef LTTNG_HAVE_STATEDUMP_CPU_TOPOLOGY
 392 static
 393 int lttng_enumerate_cpu_topology(struct lttng_session *session)
 394 {
 395         int cpu;
 396         const cpumask_t *cpumask = cpu_possible_mask;
 397
 398         for (cpu = cpumask_first(cpumask); cpu < nr_cpu_ids;
 399                         cpu = cpumask_next(cpu, cpumask)) {
 400                 trace_lttng_statedump_cpu_topology(session, &cpu_data(cpu));
 401         }
 402
 403         return 0;
 404 }
 405 #else
 406 static
 407 int lttng_enumerate_cpu_topology(struct lttng_session *session)
 408 {
 409         return 0;
 410 }
 411 #endif
 412
 413 #if 0
 414 /*
 415  * FIXME: we cannot take a mmap_sem while in a RCU read-side critical section
 416  * (scheduling in atomic). Normally, the tasklist lock protects this kind of
 417  * iteration, but it is not exported to modules.
 418  */
 419 static
 420 void lttng_enumerate_task_vm_maps(struct lttng_session *session,
 421                 struct task_struct *p)
 422 {
 423         struct mm_struct *mm;
 424         struct vm_area_struct *map;
 425         unsigned long ino;
 426
 427         /* get_task_mm does a task_lock... */
 428         mm = get_task_mm(p);
 429         if (!mm)
 430                 return;
 431
 432         map = mm->mmap;
 433         if (map) {
 434                 down_read(&mm->mmap_sem);
 435                 while (map) {
 436                         if (map->vm_file)
 437                                 ino = map->vm_file->lttng_f_dentry->d_inode->i_ino;
 438                         else
 439                                 ino = 0;
 440                         trace_lttng_statedump_vm_map(session, p, map, ino);
 441                         map = map->vm_next;
 442                 }
 443                 up_read(&mm->mmap_sem);
 444         }
 445         mmput(mm);
 446 }
 447
 448 static
 449 int lttng_enumerate_vm_maps(struct lttng_session *session)
 450 {
 451         struct task_struct *p;
 452
 453         rcu_read_lock();
 454         for_each_process(p)
 455                 lttng_enumerate_task_vm_maps(session, p);
 456         rcu_read_unlock();
 457         return 0;
 458 }
 459 #endif
 460
 461 #ifdef CONFIG_LTTNG_HAS_LIST_IRQ
 462
 463 static
 464 int lttng_list_interrupts(struct lttng_session *session)
 465 {
 466         unsigned int irq;
 467         unsigned long flags = 0;
 468         struct irq_desc *desc;
 469
 470 #define irq_to_desc     wrapper_irq_to_desc
 471         /* needs irq_desc */
 472         for_each_irq_desc(irq, desc) {
 473                 struct irqaction *action;
 474                 const char *irq_chip_name =
 475                         irq_desc_get_chip(desc)->name ? : "unnamed_irq_chip";
 476
 477                 local_irq_save(flags);
 478                 raw_spin_lock(&desc->lock);
 479                 for (action = desc->action; action; action = action->next) {
 480                         trace_lttng_statedump_interrupt(session,
 481                                 irq, irq_chip_name, action);
 482                 }
 483                 raw_spin_unlock(&desc->lock);
 484                 local_irq_restore(flags);
 485         }
 486         return 0;
 487 #undef irq_to_desc
 488 }
 489 #else
 490 static inline
 491 int lttng_list_interrupts(struct lttng_session *session)
 492 {
 493         return 0;
 494 }
 495 #endif
 496
 497 /*
 498  * Statedump the task's namespaces using the proc filesystem inode number as
 499  * the unique identifier. The user and pid ns are nested and will be dumped
 500  * recursively.
 501  *
 502  * Called with task lock held.
 503  */
 504 static
 505 void lttng_statedump_process_ns(struct lttng_session *session,
 506                 struct task_struct *p,
 507                 enum lttng_thread_type type,
 508                 enum lttng_execution_mode mode,
 509                 enum lttng_execution_submode submode,
 510                 enum lttng_process_status status)
 511 {
 512         struct nsproxy *proxy;
 513         struct pid_namespace *pid_ns;
 514         struct user_namespace *user_ns;
 515
 516         /*
 517          * The pid and user namespaces are special, they are nested and
 518          * accessed with specific functions instead of the nsproxy struct
 519          * like the other namespaces.
 520          */
 521         pid_ns = task_active_pid_ns(p);
 522         do {
 523                 trace_lttng_statedump_process_pid_ns(session, p, pid_ns);
 524                 pid_ns = pid_ns ? pid_ns->parent : NULL;
 525         } while (pid_ns);
 526
 527
 528         user_ns = task_cred_xxx(p, user_ns);
 529         do {
 530                 trace_lttng_statedump_process_user_ns(session, p, user_ns);
 531                 /*
 532                  * trace_lttng_statedump_process_user_ns() internally
 533                  * checks whether user_ns is NULL. While this does not
 534                  * appear to be a possible return value for
 535                  * task_cred_xxx(), err on the safe side and check
 536                  * for NULL here as well to be consistent with the
 537                  * paranoid behavior of
 538                  * trace_lttng_statedump_process_user_ns().
 539                  */
 540                 user_ns = user_ns ? user_ns->lttng_user_ns_parent : NULL;
 541         } while (user_ns);
 542
 543         /*
 544          * Back and forth on locking strategy within Linux upstream for nsproxy.
 545          * See Linux upstream commit 728dba3a39c66b3d8ac889ddbe38b5b1c264aec3
 546          * "namespaces: Use task_lock and not rcu to protect nsproxy"
 547          * for details.
 548          */
 549 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(3,17,0) || \
 550                 LTTNG_UBUNTU_KERNEL_RANGE(3,13,11,36, 3,14,0,0) || \
 551                 LTTNG_UBUNTU_KERNEL_RANGE(3,16,1,11, 3,17,0,0) || \
 552                 LTTNG_RHEL_KERNEL_RANGE(3,10,0,229,13,0, 3,11,0,0,0,0))
 553         proxy = p->nsproxy;
 554 #else
 555         rcu_read_lock();
 556         proxy = task_nsproxy(p);
 557 #endif
 558         if (proxy) {
 559 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,6,0))
 560                 trace_lttng_statedump_process_cgroup_ns(session, p, proxy->cgroup_ns);
 561 #endif
 562                 trace_lttng_statedump_process_ipc_ns(session, p, proxy->ipc_ns);
 563 #ifndef LTTNG_MNT_NS_MISSING_HEADER
 564                 trace_lttng_statedump_process_mnt_ns(session, p, proxy->mnt_ns);
 565 #endif
 566                 trace_lttng_statedump_process_net_ns(session, p, proxy->net_ns);
 567                 trace_lttng_statedump_process_uts_ns(session, p, proxy->uts_ns);
 568         }
 569 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(3,17,0) || \
 570                 LTTNG_UBUNTU_KERNEL_RANGE(3,13,11,36, 3,14,0,0) || \
 571                 LTTNG_UBUNTU_KERNEL_RANGE(3,16,1,11, 3,17,0,0) || \
 572                 LTTNG_RHEL_KERNEL_RANGE(3,10,0,229,13,0, 3,11,0,0,0,0))
 573         /* (nothing) */
 574 #else
 575         rcu_read_unlock();
 576 #endif
 577 }
 578
 579 static
 580 int lttng_enumerate_process_states(struct lttng_session *session)
 581 {
 582         struct task_struct *g, *p;
 583         char *tmp;
 584
 585         tmp = (char *) __get_free_page(GFP_KERNEL);
 586         if (!tmp)
 587                 return -ENOMEM;
 588
 589         rcu_read_lock();
 590         for_each_process(g) {
 591                 struct files_struct *prev_files = NULL;
 592
 593                 p = g;
 594                 do {
 595                         enum lttng_execution_mode mode =
 596                                 LTTNG_MODE_UNKNOWN;
 597                         enum lttng_execution_submode submode =
 598                                 LTTNG_UNKNOWN;
 599                         enum lttng_process_status status;
 600                         enum lttng_thread_type type;
 601                         struct files_struct *files;
 602
 603                         task_lock(p);
 604                         if (p->exit_state == EXIT_ZOMBIE)
 605                                 status = LTTNG_ZOMBIE;
 606                         else if (p->exit_state == EXIT_DEAD)
 607                                 status = LTTNG_DEAD;
 608                         else if (p->state == TASK_RUNNING) {
 609                                 /* Is this a forked child that has not run yet? */
 610                                 if (list_empty(&p->rt.run_list))
 611                                         status = LTTNG_WAIT_FORK;
 612                                 else
 613                                         /*
 614                                          * All tasks are considered as wait_cpu;
 615                                          * the viewer will sort out if the task
 616                                          * was really running at this time.
 617                                          */
 618                                         status = LTTNG_WAIT_CPU;
 619                         } else if (p->state &
 620                                 (TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE)) {
 621                                 /* Task is waiting for something to complete */
 622                                 status = LTTNG_WAIT;
 623                         } else
 624                                 status = LTTNG_UNNAMED;
 625                         submode = LTTNG_NONE;
 626
 627                         /*
 628                          * Verification of t->mm is to filter out kernel
 629                          * threads; Viewer will further filter out if a
 630                          * user-space thread was in syscall mode or not.
 631                          */
 632                         if (p->mm)
 633                                 type = LTTNG_USER_THREAD;
 634                         else
 635                                 type = LTTNG_KERNEL_THREAD;
 636                         files = p->files;
 637
 638                         trace_lttng_statedump_process_state(session,
 639                                 p, type, mode, submode, status, files);
 640                         lttng_statedump_process_ns(session,
 641                                 p, type, mode, submode, status);
 642                         /*
 643                          * As an optimisation for the common case, do not
 644                          * repeat information for the same files_struct in
 645                          * two consecutive threads. This is the common case
 646                          * for threads sharing the same fd table. RCU guarantees
 647                          * that the same files_struct pointer is not re-used
 648                          * throughout processes/threads iteration.
 649                          */
 650                         if (files && files != prev_files) {
 651                                 lttng_enumerate_files(session, files, tmp);
 652                                 prev_files = files;
 653                         }
 654                         task_unlock(p);
 655                 } while_each_thread(g, p);
 656         }
 657         rcu_read_unlock();
 658
 659         free_page((unsigned long) tmp);
 660
 661         return 0;
 662 }
 663
 664 static
 665 void lttng_statedump_work_func(struct work_struct *work)
 666 {
 667         if (atomic_dec_and_test(&kernel_threads_to_run))
 668                 /* If we are the last thread, wake up do_lttng_statedump */
 669                 wake_up(&statedump_wq);
 670 }
 671
 672 static
 673 int do_lttng_statedump(struct lttng_session *session)
 674 {
 675         int cpu, ret;
 676
 677         trace_lttng_statedump_start(session);
 678         ret = lttng_enumerate_process_states(session);
 679         if (ret)
 680                 return ret;
 681         /*
 682          * FIXME
 683          * ret = lttng_enumerate_vm_maps(session);
 684          * if (ret)
 685          *      return ret;
 686          */
 687         ret = lttng_list_interrupts(session);
 688         if (ret)
 689                 return ret;
 690         ret = lttng_enumerate_network_ip_interface(session);
 691         if (ret)
 692                 return ret;
 693         ret = lttng_enumerate_block_devices(session);
 694         switch (ret) {
 695         case 0:
 696                 break;
 697         case -ENOSYS:
 698                 printk(KERN_WARNING "LTTng: block device enumeration is not supported by kernel\n");
 699                 break;
 700         default:
 701                 return ret;
 702         }
 703         ret = lttng_enumerate_cpu_topology(session);
 704         if (ret)
 705                 return ret;
 706
 707         /* TODO lttng_dump_idt_table(session); */
 708         /* TODO lttng_dump_softirq_vec(session); */
 709         /* TODO lttng_list_modules(session); */
 710         /* TODO lttng_dump_swap_files(session); */
 711
 712         /*
 713          * Fire off a work queue on each CPU. Their sole purpose in life
 714          * is to guarantee that each CPU has been in a state where is was in
 715          * syscall mode (i.e. not in a trap, an IRQ or a soft IRQ).
 716          */
 717         get_online_cpus();
 718         atomic_set(&kernel_threads_to_run, num_online_cpus());
 719         for_each_online_cpu(cpu) {
 720                 INIT_DELAYED_WORK(&cpu_work[cpu], lttng_statedump_work_func);
 721                 schedule_delayed_work_on(cpu, &cpu_work[cpu], 0);
 722         }
 723         /* Wait for all threads to run */
 724         __wait_event(statedump_wq, (atomic_read(&kernel_threads_to_run) == 0));
 725         put_online_cpus();
 726         /* Our work is done */
 727         trace_lttng_statedump_end(session);
 728         return 0;
 729 }
 730
 731 /*
 732  * Called with session mutex held.
 733  */
 734 int lttng_statedump_start(struct lttng_session *session)
 735 {
 736         return do_lttng_statedump(session);
 737 }
 738 EXPORT_SYMBOL_GPL(lttng_statedump_start);
 739
 740 static
 741 int __init lttng_statedump_init(void)
 742 {
 743         /*
 744          * Allow module to load even if the fixup cannot be done. This
 745          * will allow seemless transition when the underlying issue fix
 746          * is merged into the Linux kernel, and when tracepoint.c
 747          * "tracepoint_module_notify" is turned into a static function.
 748          */
 749         (void) wrapper_lttng_fixup_sig(THIS_MODULE);
 750         return 0;
 751 }
 752
 753 module_init(lttng_statedump_init);
 754
 755 static
 756 void __exit lttng_statedump_exit(void)
 757 {
 758 }
 759
 760 module_exit(lttng_statedump_exit);
 761
 762 MODULE_LICENSE("GPL and additional rights");
 763 MODULE_AUTHOR("Jean-Hugues Deschenes");
 764 MODULE_DESCRIPTION("LTTng statedump provider");
 765 MODULE_VERSION(__stringify(LTTNG_MODULES_MAJOR_VERSION) "."
 766         __stringify(LTTNG_MODULES_MINOR_VERSION) "."
 767         __stringify(LTTNG_MODULES_PATCHLEVEL_VERSION)
 768         LTTNG_MODULES_EXTRAVERSION);