The marker activation functions sits in kernel/marker.c. A hash table is used to keep track of the registered probes and armed markers, so the markers within a newly loaded module that should be active can be activated at module load time. marker_query has been removed. marker_get_first, marker_get_next and marker_release should be used as iterators on the markers. Changelog: - markers_mutex now nests inside module_mutex rather than the opposite. - Iteration on modules is now done in module.c. - module_mutex is not exported anymore. Signed-off-by: Mathieu Desnoyers Acked-by: "Frank Ch. Eigler" CC: Christoph Hellwig CC: Rusty Russell --- include/asm-generic/vmlinux.lds.h | 11 include/linux/marker.h | 175 ++++++++++ include/linux/module.h | 18 + kernel/marker.c | 608 ++++++++++++++++++++++++++++++++++++++ kernel/module.c | 66 ++++ 5 files changed, 875 insertions(+), 3 deletions(-) Index: linux-2.6-lttng/include/asm-generic/vmlinux.lds.h =================================================================== --- linux-2.6-lttng.orig/include/asm-generic/vmlinux.lds.h 2007-09-14 10:11:18.000000000 -0400 +++ linux-2.6-lttng/include/asm-generic/vmlinux.lds.h 2007-09-14 10:11:31.000000000 -0400 @@ -12,7 +12,11 @@ /* .data section */ #define DATA_DATA \ *(.data) \ - *(.data.init.refok) + *(.data.init.refok) \ + . = ALIGN(8); \ + VMLINUX_SYMBOL(__start___markers) = .; \ + *(__markers) \ + VMLINUX_SYMBOL(__stop___markers) = .; #define RO_DATA(align) \ . = ALIGN((align)); \ @@ -129,6 +133,11 @@ VMLINUX_SYMBOL(__stop___immediate) = .; \ } \ \ + /* Markers: strings */ \ + __markers_strings : AT(ADDR(__markers_strings) - LOAD_OFFSET) { \ + *(__markers_strings) \ + } \ + \ /* Kernel symbol table: strings */ \ __ksymtab_strings : AT(ADDR(__ksymtab_strings) - LOAD_OFFSET) { \ *(__ksymtab_strings) \ Index: linux-2.6-lttng/include/linux/marker.h =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ linux-2.6-lttng/include/linux/marker.h 2007-09-17 12:43:54.000000000 -0400 @@ -0,0 +1,175 @@ +#ifndef _LINUX_MARKER_H +#define _LINUX_MARKER_H + +/* + * Code markup for dynamic and static tracing. + * + * See Documentation/marker.txt. + * + * (C) Copyright 2006 Mathieu Desnoyers + * + * This file is released under the GPLv2. + * See the file COPYING for more details. + */ + +#include +#include + +struct module; +struct __mark_marker; + +/** + * marker_probe_func - Type of a marker probe function + * @mdata: pointer of type struct __mark_marker + * @private_data: caller site private data + * @fmt: format string + * @...: variable argument list + * + * Type of marker probe functions. They receive the mdata and need to parse the + * format string to recover the variable argument list. + */ +typedef void marker_probe_func(const struct __mark_marker *mdata, + void *private_data, const char *fmt, ...); + +struct __mark_marker { + const char *name; /* Marker name */ + const char *format; /* Marker format string, describing the + * variable argument list. + */ + const char *args; /* List of arguments litteraly transformed + * into a string: "arg1, arg2, arg3". + */ + DEFINE_IMMEDIATE(char, state); /* Immediate value state. */ + marker_probe_func *call;/* Probe handler function pointer */ + void *pdata; /* Private probe data */ +} __attribute__((aligned(8))); + +#ifdef CONFIG_MARKERS + +/* + * Generic marker flavor always available. + * Note : the empty asm volatile with read constraint is used here instead of a + * "used" attribute to fix a gcc 4.1.x bug. + * Make sure the alignment of the structure in the __markers section will + * not add unwanted padding between the beginning of the section and the + * structure. Force alignment to the same alignment as the section start. + */ +#define __trace_mark(generic, name, call_data, format, args...) \ + do { \ + static const char __mstrtab_name_##name[] \ + __attribute__((section("__markers_strings"))) \ + = #name; \ + static const char __mstrtab_format_##name[] \ + __attribute__((section("__markers_strings"))) \ + = format; \ + static const char __mstrtab_args_##name[] \ + __attribute__((section("__markers_strings"))) \ + = #args; \ + static struct __mark_marker __mark_##name \ + __attribute__((section("__markers"))) = \ + { __mstrtab_name_##name, __mstrtab_format_##name, \ + __mstrtab_args_##name, 0, \ + __mark_empty_function, NULL }; \ + asm volatile ( "" : : "i" (&__mark_##name)); \ + __mark_check_format(format, ## args); \ + if (!generic) { \ + if (unlikely(immediate_read(__mark_##name.state))) { \ + preempt_disable(); \ + (*__mark_##name.call) \ + (&__mark_##name, call_data, \ + format, ## args); \ + preempt_enable(); \ + } \ + } else { \ + if (unlikely(_immediate_read(__mark_##name.state))) { \ + preempt_disable(); \ + (*__mark_##name.call) \ + (&__mark_##name, call_data, \ + format, ## args); \ + preempt_enable(); \ + } \ + } \ + } while (0) + +extern void marker_update_probe_range(struct __mark_marker *begin, + struct __mark_marker *end, struct module *probe_module, int *refcount); +#else /* !CONFIG_MARKERS */ +#define __trace_mark(generic, name, call_data, format, args...) \ + __mark_check_format(format, ## args) +static inline void marker_update_probe_range(struct __mark_marker *begin, + struct __mark_marker *end, struct module *probe_module, int *refcount) +{ } +#endif /* CONFIG_MARKERS */ + +/** + * trace_mark - Marker using code patching + * @name: marker name, not quoted. + * @format: format string + * @args...: variable argument list + * + * Places a marker using optimized code patching technique (immediate_read()) + * to be enabled. + */ +#define trace_mark(name, format, args...) \ + __trace_mark(0, name, NULL, format, ## args) + +/** + * _trace_mark - Marker using variable read + * @name: marker name, not quoted. + * @format: format string + * @args...: variable argument list + * + * Places a marker using a standard memory read (_immediate_read()) to be + * enabled. Should be used for markers in __init and __exit functions and in + * lockdep code. + */ +#define _trace_mark(name, format, args...) \ + __trace_mark(1, name, NULL, format, ## args) + +#define MARK_MAX_FORMAT_LEN 1024 + +/** + * MARK_NOARGS - Format string for a marker with no argument. + */ +#define MARK_NOARGS " " + +/* To be used for string format validity checking with gcc */ +static inline void __attribute__ ((format (printf, 1, 2))) + __mark_check_format(const char *fmt, ...) { } + +extern marker_probe_func __mark_empty_function; + +/* + * Connect a probe to a marker. + * pdata must be a valid allocated memory address, or NULL. + */ +extern int marker_probe_register(const char *name, const char *format, + marker_probe_func *probe, void *pdata); + +/* + * Returns the pdata given to marker_probe_register. + */ +extern void *marker_probe_unregister(const char *name); +/* + * Unregister a marker by providing the registered pdata. + */ +extern void *marker_probe_unregister_pdata(void *pdata); + +extern int marker_arm(const char *name); +extern int marker_disarm(const char *name); + +struct marker_iter { + struct module *module; + struct __mark_marker *marker; +}; + +extern void marker_iter_start(struct marker_iter *iter); +extern void marker_iter_next(struct marker_iter *iter); +extern void marker_iter_stop(struct marker_iter *iter); +extern void marker_iter_reset(struct marker_iter *iter); +extern void *marker_get_pdata(const char *name); +extern int marker_get_iter_range(struct __mark_marker **marker, + struct __mark_marker *begin, + struct __mark_marker *end); + +#endif Index: linux-2.6-lttng/include/linux/module.h =================================================================== --- linux-2.6-lttng.orig/include/linux/module.h 2007-09-14 10:11:18.000000000 -0400 +++ linux-2.6-lttng/include/linux/module.h 2007-09-14 10:11:31.000000000 -0400 @@ -16,6 +16,7 @@ #include #include #include +#include #include #include @@ -376,6 +377,10 @@ struct module const struct __immediate *immediate; unsigned int num_immediate; #endif +#ifdef CONFIG_MARKERS + struct __mark_marker *markers; + unsigned int num_markers; +#endif }; #ifndef MODULE_ARCH_INIT #define MODULE_ARCH_INIT {} @@ -482,6 +487,9 @@ extern void print_modules(void); extern void _module_immediate_update(void); extern void module_immediate_update(void); +extern void module_update_markers(struct module *probe_module, int *refcount); +extern int module_get_iter_markers(struct marker_iter *iter); + #else /* !CONFIG_MODULES... */ #define EXPORT_SYMBOL(sym) #define EXPORT_SYMBOL_GPL(sym) @@ -589,6 +597,16 @@ static inline void module_immediate_upda { } +static inline void module_update_markers(struct module *probe_module, + int *refcount) +{ +} + +static inline int module_get_iter_markers(struct marker_iter *iter) +{ + return 0; +} + #endif /* CONFIG_MODULES */ struct device_driver; Index: linux-2.6-lttng/kernel/module.c =================================================================== --- linux-2.6-lttng.orig/kernel/module.c 2007-09-14 10:11:30.000000000 -0400 +++ linux-2.6-lttng/kernel/module.c 2007-09-14 10:11:31.000000000 -0400 @@ -1720,6 +1720,8 @@ static struct module *load_module(void _ unsigned int unusedgplindex; unsigned int unusedgplcrcindex; unsigned int immediateindex; + unsigned int markersindex; + unsigned int markersstringsindex; struct module *mod; long err = 0; void *percpu = NULL, *ptr = NULL; /* Stops spurious gcc warning */ @@ -1972,6 +1974,8 @@ static struct module *load_module(void _ mod->num_immediate = sechdrs[immediateindex].sh_size / sizeof(*mod->immediate); #endif + markersindex = find_sec(hdr, sechdrs, secstrings, "__markers"); + markersstringsindex = find_sec(hdr, sechdrs, secstrings, "__markers_strings"); mod->unused_syms = (void *)sechdrs[unusedindex].sh_addr; if (unusedcrcindex) @@ -2013,6 +2017,11 @@ static struct module *load_module(void _ if (err < 0) goto cleanup; } +#ifdef CONFIG_MARKERS + mod->markers = (void *)sechdrs[markersindex].sh_addr; + mod->num_markers = + sechdrs[markersindex].sh_size / sizeof(*mod->markers); +#endif /* Find duplicate symbols */ err = verify_export_symbols(mod); @@ -2037,12 +2046,16 @@ static struct module *load_module(void _ goto nomodsectinfo; #endif + if (!mod->taints) { #ifdef CONFIG_IMMEDIATE - if (!mod->taints) immediate_update_range(mod->immediate, mod->immediate + mod->num_immediate); #endif - +#ifdef CONFIG_MARKERS + marker_update_probe_range(mod->markers, + mod->markers + mod->num_markers, NULL, NULL); +#endif + } err = module_finalize(hdr, sechdrs, mod); if (err < 0) goto cleanup; @@ -2693,3 +2706,52 @@ void module_immediate_update(void) } EXPORT_SYMBOL_GPL(module_immediate_update); #endif + +#ifdef CONFIG_MARKERS +void module_update_markers(struct module *probe_module, int *refcount) +{ + struct module *mod; + + mutex_lock(&module_mutex); + list_for_each_entry(mod, &modules, list) + if (!mod->taints) + marker_update_probe_range(mod->markers, + mod->markers + mod->num_markers, + probe_module, refcount); + mutex_unlock(&module_mutex); +} +EXPORT_SYMBOL_GPL(module_update_markers); + +/* + * Returns 0 if current not found. + * Returns 1 if current found. + */ +int module_get_iter_markers(struct marker_iter *iter) +{ + struct module *iter_mod; + int found = 0; + + mutex_lock(&module_mutex); + list_for_each_entry(iter_mod, &modules, list) { + if (!iter_mod->taints) { + /* + * Sorted module list + */ + if (iter_mod < iter->module) + continue; + else if (iter_mod > iter->module) + iter->marker = NULL; + found = marker_get_iter_range(&iter->marker, + iter_mod->markers, + iter_mod->markers + iter_mod->num_markers); + if (found) { + iter->module = iter_mod; + break; + } + } + } + mutex_unlock(&module_mutex); + return found; +} +EXPORT_SYMBOL_GPL(module_get_iter_markers); +#endif Index: linux-2.6-lttng/kernel/marker.c =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ linux-2.6-lttng/kernel/marker.c 2007-09-14 10:11:31.000000000 -0400 @@ -0,0 +1,608 @@ +/* + * Copyright (C) 2007 Mathieu Desnoyers + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include + +extern struct __mark_marker __start___markers[]; +extern struct __mark_marker __stop___markers[]; + +/* + * module_mutex nests inside markers_mutex. Markers mutex protects the builtin + * and module markers, the hash table and deferred_sync. + */ +DEFINE_MUTEX(markers_mutex); + +/* + * Marker deferred synchronization. + * Upon marker probe_unregister, we delay call to synchronize_sched() to + * accelerate mass unregistration (only when there is no more reference to a + * given module do we call synchronize_sched()). However, we need to make sure + * every critical region has ended before we re-arm a marker that has been + * unregistered and then registered back with a different probe data. + */ +static int deferred_sync; + +/* + * Marker hash table, containing the active markers. + * Protected by module_mutex. + */ +#define MARKER_HASH_BITS 6 +#define MARKER_TABLE_SIZE (1 << MARKER_HASH_BITS) + +struct marker_entry { + struct hlist_node hlist; + char *format; + marker_probe_func *probe; + void *pdata; + int refcount; /* Number of times armed. 0 if disarmed. */ + char name[0]; /* Contains name'\0'format'\0' */ +}; + +static struct hlist_head marker_table[MARKER_TABLE_SIZE]; + +/** + * __mark_empty_function - Empty probe callback + * @mdata: pointer of type const struct __mark_marker + * @fmt: format string + * @...: variable argument list + * + * Empty callback provided as a probe to the markers. By providing this to a + * disabled marker, we make sure the execution flow is always valid even + * though the function pointer change and the marker enabling are two distinct + * operations that modifies the execution flow of preemptible code. + */ +void __mark_empty_function(const struct __mark_marker *mdata, + void *private_data, + const char *fmt, ...) +{ } +EXPORT_SYMBOL_GPL(__mark_empty_function); + +/* + * Get marker if the marker is present in the marker hash table. + * Must be called with markers_mutex held. + * Returns NULL if not present. + */ +static struct marker_entry *get_marker(const char *name) +{ + struct hlist_head *head; + struct hlist_node *node; + struct marker_entry *e; + u32 hash = jhash(name, strlen(name), 0); + + head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)]; + hlist_for_each_entry(e, node, head, hlist) { + if (!strcmp(name, e->name)) + return e; + } + return NULL; +} + +/* + * Add the marker to the marker hash table. Must be called with markers_mutex + * held. + */ +static int add_marker(const char *name, + const char *format, marker_probe_func *probe, void *pdata) +{ + struct hlist_head *head; + struct hlist_node *node; + struct marker_entry *e; + size_t name_len = strlen(name) + 1; + size_t format_len = 0; + u32 hash = jhash(name, name_len-1, 0); + + if (format) + format_len = strlen(format) + 1; + head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)]; + hlist_for_each_entry(e, node, head, hlist) { + if (!strcmp(name, e->name)) { + printk(KERN_NOTICE + "Marker %s busy, probe %p already installed\n", + name, e->probe); + return -EBUSY; /* Already there */ + } + } + /* + * Using kmalloc here to allocate a variable length element. Could + * cause some memory fragmentation if overused. + */ + e = kmalloc(sizeof(struct marker_entry) + name_len + format_len, + GFP_KERNEL); + if (!e) + return -ENOMEM; + memcpy(&e->name[0], name, name_len); + if (format) { + e->format = &e->name[name_len]; + memcpy(e->format, format, format_len); + trace_mark(core_marker_format, "name %s format %s", + e->name, e->format); + } else + e->format = NULL; + e->probe = probe; + e->pdata = pdata; + e->refcount = 0; + hlist_add_head(&e->hlist, head); + return 0; +} + +/* + * Remove the marker from the marker hash table. Must be called with mutex_lock + * held. + */ +static void *remove_marker(const char *name) +{ + struct hlist_head *head; + struct hlist_node *node; + struct marker_entry *e; + int found = 0; + size_t len = strlen(name) + 1; + void *pdata = NULL; + u32 hash = jhash(name, len-1, 0); + + head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)]; + hlist_for_each_entry(e, node, head, hlist) { + if (!strcmp(name, e->name)) { + found = 1; + break; + } + } + if (found) { + pdata = e->pdata; + hlist_del(&e->hlist); + kfree(e); + } + return pdata; +} + +/* + * Set the mark_entry format to the format found in the element. + */ +static int marker_set_format(struct marker_entry **entry, const char *format) +{ + struct marker_entry *e; + size_t name_len = strlen((*entry)->name) + 1; + size_t format_len = strlen(format) + 1; + + e = kmalloc(sizeof(struct marker_entry) + name_len + format_len, + GFP_KERNEL); + if (!e) + return -ENOMEM; + memcpy(&e->name[0], (*entry)->name, name_len); + e->format = &e->name[name_len]; + memcpy(e->format, format, format_len); + e->probe = (*entry)->probe; + e->pdata = (*entry)->pdata; + e->refcount = (*entry)->refcount; + hlist_add_before(&e->hlist, &(*entry)->hlist); + hlist_del(&(*entry)->hlist); + kfree(*entry); + *entry = e; + trace_mark(core_marker_format, "name %s format %s", + e->name, e->format); + return 0; +} + +/* + * Sets the probe callback corresponding to one marker. + */ +static int set_marker(struct marker_entry **entry, + struct __mark_marker *elem) +{ + int ret; + BUG_ON(strcmp((*entry)->name, elem->name) != 0); + + if ((*entry)->format) { + if (strcmp((*entry)->format, elem->format) != 0) { + printk(KERN_NOTICE + "Format mismatch for probe %s " + "(%s), marker (%s)\n", + (*entry)->name, + (*entry)->format, + elem->format); + return -EPERM; + } + } else { + ret = marker_set_format(entry, elem->format); + if (ret) + return ret; + } + elem->call = (*entry)->probe; + elem->pdata = (*entry)->pdata; + _immediate_set(elem->state, 1); + return 0; +} + +/* + * Disable a marker and its probe callback. + * Note: only after a synchronize_sched() issued after setting elem->call to the + * empty function insures that the original callback is not used anymore. This + * insured by preemption disabling around the call site. + */ +static void disable_marker(struct __mark_marker *elem) +{ + _immediate_set(elem->state, 0); + elem->call = __mark_empty_function; + /* + * Leave the pdata and id there, because removal is racy and should be + * done only after a synchronize_sched(). These are never used until + * the next initialization anyway. + */ +} + +/** + * marker_update_probe_range - Update a probe range + * @begin: beginning of the range + * @end: end of the range + * @probe_module: module address of the probe being updated + * @refcount: number of references left to the given probe_module (out) + * + * Updates the probe callback corresponding to a range of markers. + * Must be called with markers_mutex held. + */ +void marker_update_probe_range( + struct __mark_marker *begin, + struct __mark_marker *end, + struct module *probe_module, + int *refcount) +{ + struct __mark_marker *iter; + struct marker_entry *mark_entry; + + for (iter = begin; iter < end; iter++) { + mark_entry = get_marker(iter->name); + if (mark_entry && mark_entry->refcount) { + set_marker(&mark_entry, iter); + /* + * ignore error, continue + */ + if (probe_module) + if (probe_module == + __module_text_address((unsigned long)mark_entry->probe)) + (*refcount)++; + } else { + disable_marker(iter); + } + } +} +EXPORT_SYMBOL_GPL(marker_update_probe_range); + +/* + * Update probes, removing the faulty probes. + * Issues a synchronize_sched() when no reference to the module passed + * as parameter is found in the probes so the probe module can be + * safely unloaded from now on. + */ +static inline void marker_update_probes(struct module *probe_module) +{ + int refcount = 0; + + mutex_lock(&markers_mutex); + /* Core kernel markers */ + marker_update_probe_range(__start___markers, + __stop___markers, probe_module, &refcount); + /* Markers in modules. */ + module_update_markers(probe_module, &refcount); + if (probe_module && refcount == 0) { + synchronize_sched(); + deferred_sync = 0; + } + mutex_unlock(&markers_mutex); +} + +/** + * marker_probe_register - Connect a probe to a marker + * @name: marker name + * @format: format string + * @probe: probe handler + * @pdata: probe private data + * + * pdata must be a valid allocated memory address, or NULL. + * Returns 0 if ok, error value on error. + */ +int marker_probe_register(const char *name, const char *format, + marker_probe_func *probe, void *pdata) +{ + struct marker_entry *entry; + int ret = 0, need_update = 0; + + mutex_lock(&markers_mutex); + entry = get_marker(name); + if (entry && entry->refcount) { + ret = -EBUSY; + goto end; + } + if (deferred_sync) { + synchronize_sched(); + deferred_sync = 0; + } + ret = add_marker(name, format, probe, pdata); + if (ret) + goto end; + need_update = 1; +end: + mutex_unlock(&markers_mutex); + if (need_update) + marker_update_probes(NULL); + return ret; +} +EXPORT_SYMBOL_GPL(marker_probe_register); + +/** + * marker_probe_unregister - Disconnect a probe from a marker + * @name: marker name + * + * Returns the pdata given to marker_probe_register, or an ERR_PTR(). + */ +void *marker_probe_unregister(const char *name) +{ + struct module *probe_module; + struct marker_entry *entry; + void *pdata; + int need_update = 0; + + mutex_lock(&markers_mutex); + entry = get_marker(name); + if (!entry) { + pdata = ERR_PTR(-ENOENT); + goto end; + } + entry->refcount = 0; + /* In what module is the probe handler ? */ + probe_module = __module_text_address((unsigned long)entry->probe); + pdata = remove_marker(name); + deferred_sync = 1; + need_update = 1; +end: + mutex_unlock(&markers_mutex); + if (need_update) + marker_update_probes(probe_module); + return pdata; +} +EXPORT_SYMBOL_GPL(marker_probe_unregister); + +/** + * marker_probe_unregister_pdata - Disconnect a probe from a marker + * @pdata: probe private data + * + * Unregister a marker by providing the registered pdata. + * Returns the pdata given to marker_probe_register, or an ERR_PTR(). + */ +void *marker_probe_unregister_pdata(void *pdata) +{ + struct module *probe_module; + struct hlist_head *head; + struct hlist_node *node; + struct marker_entry *entry; + int found = 0; + unsigned int i; + int need_update = 0; + + mutex_lock(&markers_mutex); + for (i = 0; i < MARKER_TABLE_SIZE; i++) { + head = &marker_table[i]; + hlist_for_each_entry(entry, node, head, hlist) { + if (entry->pdata == pdata) { + found = 1; + goto iter_end; + } + } + } +iter_end: + if (!found) { + pdata = ERR_PTR(-ENOENT); + goto end; + } + entry->refcount = 0; + /* In what module is the probe handler ? */ + probe_module = __module_text_address((unsigned long)entry->probe); + pdata = remove_marker(entry->name); + deferred_sync = 1; + need_update = 1; +end: + mutex_unlock(&markers_mutex); + if (need_update) + marker_update_probes(probe_module); + return pdata; +} +EXPORT_SYMBOL_GPL(marker_probe_unregister_pdata); + +/** + * marker_arm - Arm a marker + * @name: marker name + * + * Activate a marker. It keeps a reference count of the number of + * arming/disarming done. + * Returns 0 if ok, error value on error. + */ +int marker_arm(const char *name) +{ + struct marker_entry * entry; + int ret = 0, need_update = 0; + + mutex_lock(&markers_mutex); + entry = get_marker(name); + if (!entry) { + ret = -ENOENT; + goto end; + } + /* + * Only need to update probes when refcount passes from 0 to 1. + */ + if (entry->refcount++) + goto end; + need_update = 1; +end: + mutex_unlock(&markers_mutex); + if (need_update) + marker_update_probes(NULL); + return ret; +} +EXPORT_SYMBOL_GPL(marker_arm); + +/** + * marker_disarm - Disarm a marker + * @name: marker name + * + * Disarm a marker. It keeps a reference count of the number of arming/disarming + * done. + * Returns 0 if ok, error value on error. + */ +int marker_disarm(const char *name) +{ + struct marker_entry * entry; + int ret = 0, need_update = 0; + + mutex_lock(&markers_mutex); + entry = get_marker(name); + if (!entry) { + ret = -ENOENT; + goto end; + } + /* + * Only permit decrement refcount if higher than 0. + * Do probe update only on 1 -> 0 transition. + */ + if (entry->refcount) { + if (--entry->refcount) + goto end; + } else { + ret = -EPERM; + goto end; + } + need_update = 1; +end: + mutex_unlock(&markers_mutex); + if (need_update) + marker_update_probes(NULL); + return ret; +} +EXPORT_SYMBOL_GPL(marker_disarm); + +/** + * marker_get_pdata - Get a marker's probe private data + * @name: marker name + * + * Returns the pdata pointer, or an ERR_PTR. + * The pdata pointer should _only_ be dereferenced if the caller is the owner of + * the data, or its content could vanish. This is mostly used to confirm that a + * caller is the owner of a registered probe. + */ +void *marker_get_pdata(const char *name) +{ + struct hlist_head *head; + struct hlist_node *node; + struct marker_entry *e; + size_t name_len = strlen(name) + 1; + u32 hash = jhash(name, name_len-1, 0); + int found = 0; + + head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)]; + hlist_for_each_entry(e, node, head, hlist) { + if (!strcmp(name, e->name)) { + found = 1; + return e->pdata; + } + } + return ERR_PTR(-ENOENT); +} +EXPORT_SYMBOL_GPL(marker_get_pdata); + +/** + * marker_get_iter_range - Get a next marker iterator given a range. + * @marker: current markers (in), next marker (out) + * @begin: beginning of the range + * @end: end of the range + * + * Returns whether a next marker has been found (1) or not (0). + * Will return the first marker in the range if the input marker is NULL. + */ +int marker_get_iter_range(struct __mark_marker **marker, + struct __mark_marker *begin, + struct __mark_marker *end) +{ + int found = 0; + + if (!*marker && begin != end) { + found = 1; + *marker = begin; + } else if (*marker >= begin && *marker < end) { + found = 1; + /* + * *marker is known to be a valid marker from now on. + */ + } + return found; +} +EXPORT_SYMBOL_GPL(marker_get_iter_range); + +static inline void marker_get_iter(struct marker_iter *iter) +{ + int found = 0; + + /* Core kernel markers */ + if (!iter->module) { + found = marker_get_iter_range(&iter->marker, + __start___markers, __stop___markers); + if (found) + goto end; + } + /* Markers in modules. */ + found = module_get_iter_markers(iter); +end: + if (!found) + marker_iter_reset(iter); +} + +void marker_iter_start(struct marker_iter *iter) +{ + mutex_lock(&markers_mutex); + marker_get_iter(iter); +} +EXPORT_SYMBOL_GPL(marker_iter_start); + +void marker_iter_next(struct marker_iter *iter) +{ + iter->marker++; + /* + * iter->marker may be invalid because we blindly incremented it. + * Make sure it is valid by marshalling on the markers, getting the + * markers from following modules if necessary. + */ + marker_get_iter(iter); +} +EXPORT_SYMBOL_GPL(marker_iter_next); + +void marker_iter_stop(struct marker_iter *iter) +{ + mutex_unlock(&markers_mutex); +} +EXPORT_SYMBOL_GPL(marker_iter_stop); + +void marker_iter_reset(struct marker_iter *iter) +{ + iter->module = NULL; + iter->marker = NULL; +} +EXPORT_SYMBOL_GPL(marker_iter_reset); -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/