profile.c

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    1 /*
    2  *  linux/kernel/profile.c
    3  *  Simple profiling. Manages a direct-mapped profile hit count buffer,
    4  *  with configurable resolution, support for restricting the cpus on
    5  *  which profiling is done, and switching between cpu time and
    6  *  schedule() calls via kernel command line parameters passed at boot.
    7  *
    8  *  Scheduler profiling support, Arjan van de Ven and Ingo Molnar,
    9  *      Red Hat, July 2004
   10  *  Consolidation of architecture support code for profiling,
   11  *      Nadia Yvette Chambers, Oracle, July 2004
   12  *  Amortized hit count accounting via per-cpu open-addressed hashtables
   13  *      to resolve timer interrupt livelocks, Nadia Yvette Chambers,
   14  *      Oracle, 2004
   15  */
   16 
   17 #include <linux/export.h>
   18 #include <linux/profile.h>
   19 #include <linux/bootmem.h>
   20 #include <linux/notifier.h>
   21 #include <linux/mm.h>
   22 #include <linux/cpumask.h>
   23 #include <linux/cpu.h>
   24 #include <linux/highmem.h>
   25 #include <linux/mutex.h>
   26 #include <linux/slab.h>
   27 #include <linux/vmalloc.h>
   28 #include <asm/sections.h>
   29 #include <asm/irq_regs.h>
   30 #include <asm/ptrace.h>
   31 
   32 struct profile_hit {
   33         u32 pc, hits;
   34 };
   35 #define PROFILE_GRPSHIFT        3
   36 #define PROFILE_GRPSZ           (1 << PROFILE_GRPSHIFT)
   37 #define NR_PROFILE_HIT          (PAGE_SIZE/sizeof(struct profile_hit))
   38 #define NR_PROFILE_GRP          (NR_PROFILE_HIT/PROFILE_GRPSZ)
   39 
   40 /* Oprofile timer tick hook */
   41 static int (*timer_hook)(struct pt_regs *) __read_mostly;
   42 
   43 static atomic_t *prof_buffer;
   44 static unsigned long prof_len, prof_shift;
   45 
   46 int prof_on __read_mostly;
   47 EXPORT_SYMBOL_GPL(prof_on);
   48 
   49 static cpumask_var_t prof_cpu_mask;
   50 #ifdef CONFIG_SMP
   51 static DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits);
   52 static DEFINE_PER_CPU(int, cpu_profile_flip);
   53 static DEFINE_MUTEX(profile_flip_mutex);
   54 #endif /* CONFIG_SMP */
   55 
   56 int profile_setup(char *str)
   57 {
   58         static char schedstr[] = "schedule";
   59         static char sleepstr[] = "sleep";
   60         static char kvmstr[] = "kvm";
   61         int par;
   62 
   63         if (!strncmp(str, sleepstr, strlen(sleepstr))) {
   64 #ifdef CONFIG_SCHEDSTATS
   65                 prof_on = SLEEP_PROFILING;
   66                 if (str[strlen(sleepstr)] == ',')
   67                         str += strlen(sleepstr) + 1;
   68                 if (get_option(&str, &par))
   69                         prof_shift = par;
   70                 printk(KERN_INFO
   71                         "kernel sleep profiling enabled (shift: %ld)\n",
   72                         prof_shift);
   73 #else
   74                 printk(KERN_WARNING
   75                         "kernel sleep profiling requires CONFIG_SCHEDSTATS\n");
   76 #endif /* CONFIG_SCHEDSTATS */
   77         } else if (!strncmp(str, schedstr, strlen(schedstr))) {
   78                 prof_on = SCHED_PROFILING;
   79                 if (str[strlen(schedstr)] == ',')
   80                         str += strlen(schedstr) + 1;
   81                 if (get_option(&str, &par))
   82                         prof_shift = par;
   83                 printk(KERN_INFO
   84                         "kernel schedule profiling enabled (shift: %ld)\n",
   85                         prof_shift);
   86         } else if (!strncmp(str, kvmstr, strlen(kvmstr))) {
   87                 prof_on = KVM_PROFILING;
   88                 if (str[strlen(kvmstr)] == ',')
   89                         str += strlen(kvmstr) + 1;
   90                 if (get_option(&str, &par))
   91                         prof_shift = par;
   92                 printk(KERN_INFO
   93                         "kernel KVM profiling enabled (shift: %ld)\n",
   94                         prof_shift);
   95         } else if (get_option(&str, &par)) {
   96                 prof_shift = par;
   97                 prof_on = CPU_PROFILING;
   98                 printk(KERN_INFO "kernel profiling enabled (shift: %ld)\n",
   99                         prof_shift);
  100         }
  101         return 1;
  102 }
  103 __setup("profile=", profile_setup);
  104 
  105 
  106 int __ref profile_init(void)
  107 {
  108         int buffer_bytes;
  109         if (!prof_on)
  110                 return 0;
  111 
  112         /* only text is profiled */
  113         prof_len = (_etext - _stext) >> prof_shift;
  114         buffer_bytes = prof_len*sizeof(atomic_t);
  115 
  116         if (!alloc_cpumask_var(&prof_cpu_mask, GFP_KERNEL))
  117                 return -ENOMEM;
  118 
  119         cpumask_copy(prof_cpu_mask, cpu_possible_mask);
  120 
  121         prof_buffer = kzalloc(buffer_bytes, GFP_KERNEL|__GFP_NOWARN);
  122         if (prof_buffer)
  123                 return 0;
  124 
  125         prof_buffer = alloc_pages_exact(buffer_bytes,
  126                                         GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN);
  127         if (prof_buffer)
  128                 return 0;
  129 
  130         prof_buffer = vzalloc(buffer_bytes);
  131         if (prof_buffer)
  132                 return 0;
  133 
  134         free_cpumask_var(prof_cpu_mask);
  135         return -ENOMEM;
  136 }
  137 
  138 /* Profile event notifications */
  139 
  140 static BLOCKING_NOTIFIER_HEAD(task_exit_notifier);
  141 static ATOMIC_NOTIFIER_HEAD(task_free_notifier);
  142 static BLOCKING_NOTIFIER_HEAD(munmap_notifier);
  143 
  144 void profile_task_exit(struct task_struct *task)
  145 {
  146         blocking_notifier_call_chain(&task_exit_notifier, 0, task);
  147 }
  148 
  149 int profile_handoff_task(struct task_struct *task)
  150 {
  151         int ret;
  152         ret = atomic_notifier_call_chain(&task_free_notifier, 0, task);
  153         return (ret == NOTIFY_OK) ? 1 : 0;
  154 }
  155 
  156 void profile_munmap(unsigned long addr)
  157 {
  158         blocking_notifier_call_chain(&munmap_notifier, 0, (void *)addr);
  159 }
  160 
  161 int task_handoff_register(struct notifier_block *n)
  162 {
  163         return atomic_notifier_chain_register(&task_free_notifier, n);
  164 }
  165 EXPORT_SYMBOL_GPL(task_handoff_register);
  166 
  167 int task_handoff_unregister(struct notifier_block *n)
  168 {
  169         return atomic_notifier_chain_unregister(&task_free_notifier, n);
  170 }
  171 EXPORT_SYMBOL_GPL(task_handoff_unregister);
  172 
  173 int profile_event_register(enum profile_type type, struct notifier_block *n)
  174 {
  175         int err = -EINVAL;
  176 
  177         switch (type) {
  178         case PROFILE_TASK_EXIT:
  179                 err = blocking_notifier_chain_register(
  180                                 &task_exit_notifier, n);
  181                 break;
  182         case PROFILE_MUNMAP:
  183                 err = blocking_notifier_chain_register(
  184                                 &munmap_notifier, n);
  185                 break;
  186         }
  187 
  188         return err;
  189 }
  190 EXPORT_SYMBOL_GPL(profile_event_register);
  191 
  192 int profile_event_unregister(enum profile_type type, struct notifier_block *n)
  193 {
  194         int err = -EINVAL;
  195 
  196         switch (type) {
  197         case PROFILE_TASK_EXIT:
  198                 err = blocking_notifier_chain_unregister(
  199                                 &task_exit_notifier, n);
  200                 break;
  201         case PROFILE_MUNMAP:
  202                 err = blocking_notifier_chain_unregister(
  203                                 &munmap_notifier, n);
  204                 break;
  205         }
  206 
  207         return err;
  208 }
  209 EXPORT_SYMBOL_GPL(profile_event_unregister);
  210 
  211 int register_timer_hook(int (*hook)(struct pt_regs *))
  212 {
  213         if (timer_hook)
  214                 return -EBUSY;
  215         timer_hook = hook;
  216         return 0;
  217 }
  218 EXPORT_SYMBOL_GPL(register_timer_hook);
  219 
  220 void unregister_timer_hook(int (*hook)(struct pt_regs *))
  221 {
  222         WARN_ON(hook != timer_hook);
  223         timer_hook = NULL;
  224         /* make sure all CPUs see the NULL hook */
  225         synchronize_sched();  /* Allow ongoing interrupts to complete. */
  226 }
  227 EXPORT_SYMBOL_GPL(unregister_timer_hook);
  228 
  229 
  230 #ifdef CONFIG_SMP
  231 /*
  232  * Each cpu has a pair of open-addressed hashtables for pending
  233  * profile hits. read_profile() IPI's all cpus to request them
  234  * to flip buffers and flushes their contents to prof_buffer itself.
  235  * Flip requests are serialized by the profile_flip_mutex. The sole
  236  * use of having a second hashtable is for avoiding cacheline
  237  * contention that would otherwise happen during flushes of pending
  238  * profile hits required for the accuracy of reported profile hits
  239  * and so resurrect the interrupt livelock issue.
  240  *
  241  * The open-addressed hashtables are indexed by profile buffer slot
  242  * and hold the number of pending hits to that profile buffer slot on
  243  * a cpu in an entry. When the hashtable overflows, all pending hits
  244  * are accounted to their corresponding profile buffer slots with
  245  * atomic_add() and the hashtable emptied. As numerous pending hits
  246  * may be accounted to a profile buffer slot in a hashtable entry,
  247  * this amortizes a number of atomic profile buffer increments likely
  248  * to be far larger than the number of entries in the hashtable,
  249  * particularly given that the number of distinct profile buffer
  250  * positions to which hits are accounted during short intervals (e.g.
  251  * several seconds) is usually very small. Exclusion from buffer
  252  * flipping is provided by interrupt disablement (note that for
  253  * SCHED_PROFILING or SLEEP_PROFILING profile_hit() may be called from
  254  * process context).
  255  * The hash function is meant to be lightweight as opposed to strong,
  256  * and was vaguely inspired by ppc64 firmware-supported inverted
  257  * pagetable hash functions, but uses a full hashtable full of finite
  258  * collision chains, not just pairs of them.
  259  *
  260  * -- nyc
  261  */
  262 static void __profile_flip_buffers(void *unused)
  263 {
  264         int cpu = smp_processor_id();
  265 
  266         per_cpu(cpu_profile_flip, cpu) = !per_cpu(cpu_profile_flip, cpu);
  267 }
  268 
  269 static void profile_flip_buffers(void)
  270 {
  271         int i, j, cpu;
  272 
  273         mutex_lock(&profile_flip_mutex);
  274         j = per_cpu(cpu_profile_flip, get_cpu());
  275         put_cpu();
  276         on_each_cpu(__profile_flip_buffers, NULL, 1);
  277         for_each_online_cpu(cpu) {
  278                 struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[j];
  279                 for (i = 0; i < NR_PROFILE_HIT; ++i) {
  280                         if (!hits[i].hits) {
  281                                 if (hits[i].pc)
  282                                         hits[i].pc = 0;
  283                                 continue;
  284                         }
  285                         atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
  286                         hits[i].hits = hits[i].pc = 0;
  287                 }
  288         }
  289         mutex_unlock(&profile_flip_mutex);
  290 }
  291 
  292 static void profile_discard_flip_buffers(void)
  293 {
  294         int i, cpu;
  295 
  296         mutex_lock(&profile_flip_mutex);
  297         i = per_cpu(cpu_profile_flip, get_cpu());
  298         put_cpu();
  299         on_each_cpu(__profile_flip_buffers, NULL, 1);
  300         for_each_online_cpu(cpu) {
  301                 struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[i];
  302                 memset(hits, 0, NR_PROFILE_HIT*sizeof(struct profile_hit));
  303         }
  304         mutex_unlock(&profile_flip_mutex);
  305 }
  306 
  307 static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
  308 {
  309         unsigned long primary, secondary, flags, pc = (unsigned long)__pc;
  310         int i, j, cpu;
  311         struct profile_hit *hits;
  312 
  313         pc = min((pc - (unsigned long)_stext) >> prof_shift, prof_len - 1);
  314         i = primary = (pc & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
  315         secondary = (~(pc << 1) & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
  316         cpu = get_cpu();
  317         hits = per_cpu(cpu_profile_hits, cpu)[per_cpu(cpu_profile_flip, cpu)];
  318         if (!hits) {
  319                 put_cpu();
  320                 return;
  321         }
  322         /*
  323          * We buffer the global profiler buffer into a per-CPU
  324          * queue and thus reduce the number of global (and possibly
  325          * NUMA-alien) accesses. The write-queue is self-coalescing:
  326          */
  327         local_irq_save(flags);
  328         do {
  329                 for (j = 0; j < PROFILE_GRPSZ; ++j) {
  330                         if (hits[i + j].pc == pc) {
  331                                 hits[i + j].hits += nr_hits;
  332                                 goto out;
  333                         } else if (!hits[i + j].hits) {
  334                                 hits[i + j].pc = pc;
  335                                 hits[i + j].hits = nr_hits;
  336                                 goto out;
  337                         }
  338                 }
  339                 i = (i + secondary) & (NR_PROFILE_HIT - 1);
  340         } while (i != primary);
  341 
  342         /*
  343          * Add the current hit(s) and flush the write-queue out
  344          * to the global buffer:
  345          */
  346         atomic_add(nr_hits, &prof_buffer[pc]);
  347         for (i = 0; i < NR_PROFILE_HIT; ++i) {
  348                 atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
  349                 hits[i].pc = hits[i].hits = 0;
  350         }
  351 out:
  352         local_irq_restore(flags);
  353         put_cpu();
  354 }
  355 
  356 static int __cpuinit profile_cpu_callback(struct notifier_block *info,
  357                                         unsigned long action, void *__cpu)
  358 {
  359         int node, cpu = (unsigned long)__cpu;
  360         struct page *page;
  361 
  362         switch (action) {
  363         case CPU_UP_PREPARE:
  364         case CPU_UP_PREPARE_FROZEN:
  365                 node = cpu_to_mem(cpu);
  366                 per_cpu(cpu_profile_flip, cpu) = 0;
  367                 if (!per_cpu(cpu_profile_hits, cpu)[1]) {
  368                         page = alloc_pages_exact_node(node,
  369                                         GFP_KERNEL | __GFP_ZERO,
  370                                         0);
  371                         if (!page)
  372                                 return notifier_from_errno(-ENOMEM);
  373                         per_cpu(cpu_profile_hits, cpu)[1] = page_address(page);
  374                 }
  375                 if (!per_cpu(cpu_profile_hits, cpu)[0]) {
  376                         page = alloc_pages_exact_node(node,
  377                                         GFP_KERNEL | __GFP_ZERO,
  378                                         0);
  379                         if (!page)
  380                                 goto out_free;
  381                         per_cpu(cpu_profile_hits, cpu)[0] = page_address(page);
  382                 }
  383                 break;
  384 out_free:
  385                 page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
  386                 per_cpu(cpu_profile_hits, cpu)[1] = NULL;
  387                 __free_page(page);
  388                 return notifier_from_errno(-ENOMEM);
  389         case CPU_ONLINE:
  390         case CPU_ONLINE_FROZEN:
  391                 if (prof_cpu_mask != NULL)
  392                         cpumask_set_cpu(cpu, prof_cpu_mask);
  393                 break;
  394         case CPU_UP_CANCELED:
  395         case CPU_UP_CANCELED_FROZEN:
  396         case CPU_DEAD:
  397         case CPU_DEAD_FROZEN:
  398                 if (prof_cpu_mask != NULL)
  399                         cpumask_clear_cpu(cpu, prof_cpu_mask);
  400                 if (per_cpu(cpu_profile_hits, cpu)[0]) {
  401                         page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
  402                         per_cpu(cpu_profile_hits, cpu)[0] = NULL;
  403                         __free_page(page);
  404                 }
  405                 if (per_cpu(cpu_profile_hits, cpu)[1]) {
  406                         page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
  407                         per_cpu(cpu_profile_hits, cpu)[1] = NULL;
  408                         __free_page(page);
  409                 }
  410                 break;
  411         }
  412         return NOTIFY_OK;
  413 }
  414 #else /* !CONFIG_SMP */
  415 #define profile_flip_buffers()          do { } while (0)
  416 #define profile_discard_flip_buffers()  do { } while (0)
  417 #define profile_cpu_callback            NULL
  418 
  419 static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)
  420 {
  421         unsigned long pc;
  422         pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift;
  423         atomic_add(nr_hits, &prof_buffer[min(pc, prof_len - 1)]);
  424 }
  425 #endif /* !CONFIG_SMP */
  426 
  427 void profile_hits(int type, void *__pc, unsigned int nr_hits)
  428 {
  429         if (prof_on != type || !prof_buffer)
  430                 return;
  431         do_profile_hits(type, __pc, nr_hits);
  432 }
  433 EXPORT_SYMBOL_GPL(profile_hits);
  434 
  435 void profile_tick(int type)
  436 {
  437         struct pt_regs *regs = get_irq_regs();
  438 
  439         if (type == CPU_PROFILING && timer_hook)
  440                 timer_hook(regs);
  441         if (!user_mode(regs) && prof_cpu_mask != NULL &&
  442             cpumask_test_cpu(smp_processor_id(), prof_cpu_mask))
  443                 profile_hit(type, (void *)profile_pc(regs));
  444 }
  445 
  446 #ifdef CONFIG_PROC_FS
  447 #include <linux/proc_fs.h>
  448 #include <linux/seq_file.h>
  449 #include <asm/uaccess.h>
  450 
  451 static int prof_cpu_mask_proc_show(struct seq_file *m, void *v)
  452 {
  453         seq_cpumask(m, prof_cpu_mask);
  454         seq_putc(m, '\n');
  455         return 0;
  456 }
  457 
  458 static int prof_cpu_mask_proc_open(struct inode *inode, struct file *file)
  459 {
  460         return single_open(file, prof_cpu_mask_proc_show, NULL);
  461 }
  462 
  463 static ssize_t prof_cpu_mask_proc_write(struct file *file,
  464         const char __user *buffer, size_t count, loff_t *pos)
  465 {
  466         cpumask_var_t new_value;
  467         int err;
  468 
  469         if (!alloc_cpumask_var(&new_value, GFP_KERNEL))
  470                 return -ENOMEM;
  471 
  472         err = cpumask_parse_user(buffer, count, new_value);
  473         if (!err) {
  474                 cpumask_copy(prof_cpu_mask, new_value);
  475                 err = count;
  476         }
  477         free_cpumask_var(new_value);
  478         return err;
  479 }
  480 
  481 static const struct file_operations prof_cpu_mask_proc_fops = {
  482         .open           = prof_cpu_mask_proc_open,
  483         .read           = seq_read,
  484         .llseek         = seq_lseek,
  485         .release        = single_release,
  486         .write          = prof_cpu_mask_proc_write,
  487 };
  488 
  489 void create_prof_cpu_mask(struct proc_dir_entry *root_irq_dir)
  490 {
  491         /* create /proc/irq/prof_cpu_mask */
  492         proc_create("prof_cpu_mask", 0600, root_irq_dir, &prof_cpu_mask_proc_fops);
  493 }
  494 
  495 /*
  496  * This function accesses profiling information. The returned data is
  497  * binary: the sampling step and the actual contents of the profile
  498  * buffer. Use of the program readprofile is recommended in order to
  499  * get meaningful info out of these data.
  500  */
  501 static ssize_t
  502 read_profile(struct file *file, char __user *buf, size_t count, loff_t *ppos)
  503 {
  504         unsigned long p = *ppos;
  505         ssize_t read;
  506         char *pnt;
  507         unsigned int sample_step = 1 << prof_shift;
  508 
  509         profile_flip_buffers();
  510         if (p >= (prof_len+1)*sizeof(unsigned int))
  511                 return 0;
  512         if (count > (prof_len+1)*sizeof(unsigned int) - p)
  513                 count = (prof_len+1)*sizeof(unsigned int) - p;
  514         read = 0;
  515 
  516         while (p < sizeof(unsigned int) && count > 0) {
  517                 if (put_user(*((char *)(&sample_step)+p), buf))
  518                         return -EFAULT;
  519                 buf++; p++; count--; read++;
  520         }
  521         pnt = (char *)prof_buffer + p - sizeof(atomic_t);
  522         if (copy_to_user(buf, (void *)pnt, count))
  523                 return -EFAULT;
  524         read += count;
  525         *ppos += read;
  526         return read;
  527 }
  528 
  529 /*
  530  * Writing to /proc/profile resets the counters
  531  *
  532  * Writing a 'profiling multiplier' value into it also re-sets the profiling
  533  * interrupt frequency, on architectures that support this.
  534  */
  535 static ssize_t write_profile(struct file *file, const char __user *buf,
  536                              size_t count, loff_t *ppos)
  537 {
  538 #ifdef CONFIG_SMP
  539         extern int setup_profiling_timer(unsigned int multiplier);
  540 
  541         if (count == sizeof(int)) {
  542                 unsigned int multiplier;
  543 
  544                 if (copy_from_user(&multiplier, buf, sizeof(int)))
  545                         return -EFAULT;
  546 
  547                 if (setup_profiling_timer(multiplier))
  548                         return -EINVAL;
  549         }
  550 #endif
  551         profile_discard_flip_buffers();
  552         memset(prof_buffer, 0, prof_len * sizeof(atomic_t));
  553         return count;
  554 }
  555 
  556 static const struct file_operations proc_profile_operations = {
  557         .read           = read_profile,
  558         .write          = write_profile,
  559         .llseek         = default_llseek,
  560 };
  561 
  562 #ifdef CONFIG_SMP
  563 static void profile_nop(void *unused)
  564 {
  565 }
  566 
  567 static int create_hash_tables(void)
  568 {
  569         int cpu;
  570 
  571         for_each_online_cpu(cpu) {
  572                 int node = cpu_to_mem(cpu);
  573                 struct page *page;
  574 
  575                 page = alloc_pages_exact_node(node,
  576                                 GFP_KERNEL | __GFP_ZERO | GFP_THISNODE,
  577                                 0);
  578                 if (!page)
  579                         goto out_cleanup;
  580                 per_cpu(cpu_profile_hits, cpu)[1]
  581                                 = (struct profile_hit *)page_address(page);
  582                 page = alloc_pages_exact_node(node,
  583                                 GFP_KERNEL | __GFP_ZERO | GFP_THISNODE,
  584                                 0);
  585                 if (!page)
  586                         goto out_cleanup;
  587                 per_cpu(cpu_profile_hits, cpu)[0]
  588                                 = (struct profile_hit *)page_address(page);
  589         }
  590         return 0;
  591 out_cleanup:
  592         prof_on = 0;
  593         smp_mb();
  594         on_each_cpu(profile_nop, NULL, 1);
  595         for_each_online_cpu(cpu) {
  596                 struct page *page;
  597 
  598                 if (per_cpu(cpu_profile_hits, cpu)[0]) {
  599                         page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[0]);
  600                         per_cpu(cpu_profile_hits, cpu)[0] = NULL;
  601                         __free_page(page);
  602                 }
  603                 if (per_cpu(cpu_profile_hits, cpu)[1]) {
  604                         page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[1]);
  605                         per_cpu(cpu_profile_hits, cpu)[1] = NULL;
  606                         __free_page(page);
  607                 }
  608         }
  609         return -1;
  610 }
  611 #else
  612 #define create_hash_tables()                    ({ 0; })
  613 #endif
  614 
  615 int __ref create_proc_profile(void) /* false positive from hotcpu_notifier */
  616 {
  617         struct proc_dir_entry *entry;
  618 
  619         if (!prof_on)
  620                 return 0;
  621         if (create_hash_tables())
  622                 return -ENOMEM;
  623         entry = proc_create("profile", S_IWUSR | S_IRUGO,
  624                             NULL, &proc_profile_operations);
  625         if (!entry)
  626                 return 0;
  627         entry->size = (1+prof_len) * sizeof(atomic_t);
  628         hotcpu_notifier(profile_cpu_callback, 0);
  629         return 0;
  630 }
  631 module_init(create_proc_profile);
  632 #endif /* CONFIG_PROC_FS */
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FreeBSD/Linux Kernel Cross Reference sys/kernel/profile.c

FreeBSD/Linux Kernel Cross Reference
sys/kernel/profile.c
