diff options
Diffstat (limited to 'kernel/marker.c')
| -rw-r--r-- | kernel/marker.c | 868 |
1 files changed, 868 insertions, 0 deletions
diff --git a/kernel/marker.c b/kernel/marker.c new file mode 100644 index 0000000..e9c6b2b --- /dev/null +++ b/kernel/marker.c @@ -0,0 +1,868 @@ +/* + * 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 <linux/module.h> +#include <linux/mutex.h> +#include <linux/types.h> +#include <linux/jhash.h> +#include <linux/list.h> +#include <linux/rcupdate.h> +#include <linux/marker.h> +#include <linux/err.h> +#include <linux/slab.h> + +extern struct marker __start___markers[]; +extern struct marker __stop___markers[]; + +/* Set to 1 to enable marker debug output */ +static const int marker_debug; + +/* + * markers_mutex nests inside module_mutex. Markers mutex protects the builtin + * and module markers and the hash table. + */ +static DEFINE_MUTEX(markers_mutex); + +/* + * Marker hash table, containing the active markers. + * Protected by module_mutex. + */ +#define MARKER_HASH_BITS 6 +#define MARKER_TABLE_SIZE (1 << MARKER_HASH_BITS) + +/* + * Note about RCU : + * It is used to make sure every handler has finished using its private data + * between two consecutive operation (add or remove) on a given marker. It is + * also used to delay the free of multiple probes array until a quiescent state + * is reached. + * marker entries modifications are protected by the markers_mutex. + */ +struct marker_entry { + struct hlist_node hlist; + char *format; + /* Probe wrapper */ + void (*call)(const struct marker *mdata, void *call_private, ...); + struct marker_probe_closure single; + struct marker_probe_closure *multi; + int refcount; /* Number of times armed. 0 if disarmed. */ + struct rcu_head rcu; + void *oldptr; + int rcu_pending; + unsigned char ptype:1; + char name[0]; /* Contains name'\0'format'\0' */ +}; + +static struct hlist_head marker_table[MARKER_TABLE_SIZE]; + +/** + * __mark_empty_function - Empty probe callback + * @probe_private: probe private data + * @call_private: call site private data + * @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(void *probe_private, void *call_private, + const char *fmt, va_list *args) +{ +} +EXPORT_SYMBOL_GPL(__mark_empty_function); + +/* + * marker_probe_cb Callback that prepares the variable argument list for probes. + * @mdata: pointer of type struct marker + * @call_private: caller site private data + * @...: Variable argument list. + * + * Since we do not use "typical" pointer based RCU in the 1 argument case, we + * need to put a full smp_rmb() in this branch. This is why we do not use + * rcu_dereference() for the pointer read. + */ +void marker_probe_cb(const struct marker *mdata, void *call_private, ...) +{ + va_list args; + char ptype; + + /* + * rcu_read_lock_sched does two things : disabling preemption to make + * sure the teardown of the callbacks can be done correctly when they + * are in modules and they insure RCU read coherency. + */ + rcu_read_lock_sched(); + ptype = mdata->ptype; + if (likely(!ptype)) { + marker_probe_func *func; + /* Must read the ptype before ptr. They are not data dependant, + * so we put an explicit smp_rmb() here. */ + smp_rmb(); + func = mdata->single.func; + /* Must read the ptr before private data. They are not data + * dependant, so we put an explicit smp_rmb() here. */ + smp_rmb(); + va_start(args, call_private); + func(mdata->single.probe_private, call_private, mdata->format, + &args); + va_end(args); + } else { + struct marker_probe_closure *multi; + int i; + /* + * Read mdata->ptype before mdata->multi. + */ + smp_rmb(); + multi = mdata->multi; + /* + * multi points to an array, therefore accessing the array + * depends on reading multi. However, even in this case, + * we must insure that the pointer is read _before_ the array + * data. Same as rcu_dereference, but we need a full smp_rmb() + * in the fast path, so put the explicit barrier here. + */ + smp_read_barrier_depends(); + for (i = 0; multi[i].func; i++) { + va_start(args, call_private); + multi[i].func(multi[i].probe_private, call_private, + mdata->format, &args); + va_end(args); + } + } + rcu_read_unlock_sched(); +} +EXPORT_SYMBOL_GPL(marker_probe_cb); + +/* + * marker_probe_cb Callback that does not prepare the variable argument list. + * @mdata: pointer of type struct marker + * @call_private: caller site private data + * @...: Variable argument list. + * + * Should be connected to markers "MARK_NOARGS". + */ +void marker_probe_cb_noarg(const struct marker *mdata, void *call_private, ...) +{ + va_list args; /* not initialized */ + char ptype; + + rcu_read_lock_sched(); + ptype = mdata->ptype; + if (likely(!ptype)) { + marker_probe_func *func; + /* Must read the ptype before ptr. They are not data dependant, + * so we put an explicit smp_rmb() here. */ + smp_rmb(); + func = mdata->single.func; + /* Must read the ptr before private data. They are not data + * dependant, so we put an explicit smp_rmb() here. */ + smp_rmb(); + func(mdata->single.probe_private, call_private, mdata->format, + &args); + } else { + struct marker_probe_closure *multi; + int i; + /* + * Read mdata->ptype before mdata->multi. + */ + smp_rmb(); + multi = mdata->multi; + /* + * multi points to an array, therefore accessing the array + * depends on reading multi. However, even in this case, + * we must insure that the pointer is read _before_ the array + * data. Same as rcu_dereference, but we need a full smp_rmb() + * in the fast path, so put the explicit barrier here. + */ + smp_read_barrier_depends(); + for (i = 0; multi[i].func; i++) + multi[i].func(multi[i].probe_private, call_private, + mdata->format, &args); + } + rcu_read_unlock_sched(); +} +EXPORT_SYMBOL_GPL(marker_probe_cb_noarg); + +static void free_old_closure(struct rcu_head *head) +{ + struct marker_entry *entry = container_of(head, + struct marker_entry, rcu); + kfree(entry->oldptr); + /* Make sure we free the data before setting the pending flag to 0 */ + smp_wmb(); + entry->rcu_pending = 0; +} + +static void debug_print_probes(struct marker_entry *entry) +{ + int i; + + if (!marker_debug) + return; + + if (!entry->ptype) { + printk(KERN_DEBUG "Single probe : %p %p\n", + entry->single.func, + entry->single.probe_private); + } else { + for (i = 0; entry->multi[i].func; i++) + printk(KERN_DEBUG "Multi probe %d : %p %p\n", i, + entry->multi[i].func, + entry->multi[i].probe_private); + } +} + +static struct marker_probe_closure * +marker_entry_add_probe(struct marker_entry *entry, + marker_probe_func *probe, void *probe_private) +{ + int nr_probes = 0; + struct marker_probe_closure *old, *new; + + WARN_ON(!probe); + + debug_print_probes(entry); + old = entry->multi; + if (!entry->ptype) { + if (entry->single.func == probe && + entry->single.probe_private == probe_private) + return ERR_PTR(-EBUSY); + if (entry->single.func == __mark_empty_function) { + /* 0 -> 1 probes */ + entry->single.func = probe; + entry->single.probe_private = probe_private; + entry->refcount = 1; + entry->ptype = 0; + debug_print_probes(entry); + return NULL; + } else { + /* 1 -> 2 probes */ + nr_probes = 1; + old = NULL; + } + } else { + /* (N -> N+1), (N != 0, 1) probes */ + for (nr_probes = 0; old[nr_probes].func; nr_probes++) + if (old[nr_probes].func == probe + && old[nr_probes].probe_private + == probe_private) + return ERR_PTR(-EBUSY); + } + /* + 2 : one for new probe, one for NULL func */ + new = kzalloc((nr_probes + 2) * sizeof(struct marker_probe_closure), + GFP_KERNEL); + if (new == NULL) + return ERR_PTR(-ENOMEM); + if (!old) + new[0] = entry->single; + else + memcpy(new, old, + nr_probes * sizeof(struct marker_probe_closure)); + new[nr_probes].func = probe; + new[nr_probes].probe_private = probe_private; + entry->refcount = nr_probes + 1; + entry->multi = new; + entry->ptype = 1; + debug_print_probes(entry); + return old; +} + +static struct marker_probe_closure * +marker_entry_remove_probe(struct marker_entry *entry, + marker_probe_func *probe, void *probe_private) +{ + int nr_probes = 0, nr_del = 0, i; + struct marker_probe_closure *old, *new; + + old = entry->multi; + + debug_print_probes(entry); + if (!entry->ptype) { + /* 0 -> N is an error */ + WARN_ON(entry->single.func == __mark_empty_function); + /* 1 -> 0 probes */ + WARN_ON(probe && entry->single.func != probe); + WARN_ON(entry->single.probe_private != probe_private); + entry->single.func = __mark_empty_function; + entry->refcount = 0; + entry->ptype = 0; + debug_print_probes(entry); + return NULL; + } else { + /* (N -> M), (N > 1, M >= 0) probes */ + for (nr_probes = 0; old[nr_probes].func; nr_probes++) { + if ((!probe || old[nr_probes].func == probe) + && old[nr_probes].probe_private + == probe_private) + nr_del++; + } + } + + if (nr_probes - nr_del == 0) { + /* N -> 0, (N > 1) */ + entry->single.func = __mark_empty_function; + entry->refcount = 0; + entry->ptype = 0; + } else if (nr_probes - nr_del == 1) { + /* N -> 1, (N > 1) */ + for (i = 0; old[i].func; i++) + if ((probe && old[i].func != probe) || + old[i].probe_private != probe_private) + entry->single = old[i]; + entry->refcount = 1; + entry->ptype = 0; + } else { + int j = 0; + /* N -> M, (N > 1, M > 1) */ + /* + 1 for NULL */ + new = kzalloc((nr_probes - nr_del + 1) + * sizeof(struct marker_probe_closure), GFP_KERNEL); + if (new == NULL) + return ERR_PTR(-ENOMEM); + for (i = 0; old[i].func; i++) + if ((probe && old[i].func != probe) || + old[i].probe_private != probe_private) + new[j++] = old[i]; + entry->refcount = nr_probes - nr_del; + entry->ptype = 1; + entry->multi = new; + } + debug_print_probes(entry); + return old; +} + +/* + * 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 struct marker_entry *add_marker(const char *name, const char *format) +{ + 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\n", name); + return ERR_PTR(-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 ERR_PTR(-ENOMEM); + memcpy(&e->name[0], name, name_len); + if (format) { + e->format = &e->name[name_len]; + memcpy(e->format, format, format_len); + if (strcmp(e->format, MARK_NOARGS) == 0) + e->call = marker_probe_cb_noarg; + else + e->call = marker_probe_cb; + trace_mark(core_marker_format, "name %s format %s", + e->name, e->format); + } else { + e->format = NULL; + e->call = marker_probe_cb; + } + e->single.func = __mark_empty_function; + e->single.probe_private = NULL; + e->multi = NULL; + e->ptype = 0; + e->refcount = 0; + e->rcu_pending = 0; + hlist_add_head(&e->hlist, head); + return e; +} + +/* + * Remove the marker from the marker hash table. Must be called with mutex_lock + * held. + */ +static int 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; + 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) + return -ENOENT; + if (e->single.func != __mark_empty_function) + return -EBUSY; + hlist_del(&e->hlist); + /* Make sure the call_rcu has been executed */ + if (e->rcu_pending) + rcu_barrier_sched(); + kfree(e); + return 0; +} + +/* + * 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); + if (strcmp(e->format, MARK_NOARGS) == 0) + e->call = marker_probe_cb_noarg; + else + e->call = marker_probe_cb; + e->single = (*entry)->single; + e->multi = (*entry)->multi; + e->ptype = (*entry)->ptype; + e->refcount = (*entry)->refcount; + e->rcu_pending = 0; + hlist_add_before(&e->hlist, &(*entry)->hlist); + hlist_del(&(*entry)->hlist); + /* Make sure the call_rcu has been executed */ + if ((*entry)->rcu_pending) + rcu_barrier_sched(); + 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 marker *elem, + int active) +{ + int ret; + WARN_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; + } + + /* + * probe_cb setup (statically known) is done here. It is + * asynchronous with the rest of execution, therefore we only + * pass from a "safe" callback (with argument) to an "unsafe" + * callback (does not set arguments). + */ + elem->call = (*entry)->call; + /* + * Sanity check : + * We only update the single probe private data when the ptr is + * set to a _non_ single probe! (0 -> 1 and N -> 1, N != 1) + */ + WARN_ON(elem->single.func != __mark_empty_function + && elem->single.probe_private + != (*entry)->single.probe_private && + !elem->ptype); + elem->single.probe_private = (*entry)->single.probe_private; + /* + * Make sure the private data is valid when we update the + * single probe ptr. + */ + smp_wmb(); + elem->single.func = (*entry)->single.func; + /* + * We also make sure that the new probe callbacks array is consistent + * before setting a pointer to it. + */ + rcu_assign_pointer(elem->multi, (*entry)->multi); + /* + * Update the function or multi probe array pointer before setting the + * ptype. + */ + smp_wmb(); + elem->ptype = (*entry)->ptype; + elem->state = active; + + return 0; +} + +/* + * Disable a marker and its probe callback. + * Note: only waiting an RCU period after setting elem->call to the empty + * function insures that the original callback is not used anymore. This insured + * by rcu_read_lock_sched around the call site. + */ +static void disable_marker(struct marker *elem) +{ + /* leave "call" as is. It is known statically. */ + elem->state = 0; + elem->single.func = __mark_empty_function; + /* Update the function before setting the ptype */ + smp_wmb(); + elem->ptype = 0; /* single probe */ + /* + * Leave the private data and id there, because removal is racy and + * should be done only after an RCU period. 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 + * + * Updates the probe callback corresponding to a range of markers. + */ +void marker_update_probe_range(struct marker *begin, + struct marker *end) +{ + struct marker *iter; + struct marker_entry *mark_entry; + + mutex_lock(&markers_mutex); + for (iter = begin; iter < end; iter++) { + mark_entry = get_marker(iter->name); + if (mark_entry) { + set_marker(&mark_entry, iter, + !!mark_entry->refcount); + /* + * ignore error, continue + */ + } else { + disable_marker(iter); + } + } + mutex_unlock(&markers_mutex); +} + +/* + * Update probes, removing the faulty probes. + * + * Internal callback only changed before the first probe is connected to it. + * Single probe private data can only be changed on 0 -> 1 and 2 -> 1 + * transitions. All other transitions will leave the old private data valid. + * This makes the non-atomicity of the callback/private data updates valid. + * + * "special case" updates : + * 0 -> 1 callback + * 1 -> 0 callback + * 1 -> 2 callbacks + * 2 -> 1 callbacks + * Other updates all behave the same, just like the 2 -> 3 or 3 -> 2 updates. + * Site effect : marker_set_format may delete the marker entry (creating a + * replacement). + */ +static void marker_update_probes(void) +{ + /* Core kernel markers */ + marker_update_probe_range(__start___markers, __stop___markers); + /* Markers in modules. */ + module_update_markers(); +} + +/** + * marker_probe_register - Connect a probe to a marker + * @name: marker name + * @format: format string + * @probe: probe handler + * @probe_private: probe private data + * + * private data must be a valid allocated memory address, or NULL. + * Returns 0 if ok, error value on error. + * The probe address must at least be aligned on the architecture pointer size. + */ +int marker_probe_register(const char *name, const char *format, + marker_probe_func *probe, void *probe_private) +{ + struct marker_entry *entry; + int ret = 0; + struct marker_probe_closure *old; + + mutex_lock(&markers_mutex); + entry = get_marker(name); + if (!entry) { + entry = add_marker(name, format); + if (IS_ERR(entry)) + ret = PTR_ERR(entry); + } else if (format) { + if (!entry->format) + ret = marker_set_format(&entry, format); + else if (strcmp(entry->format, format)) + ret = -EPERM; + } + if (ret) + goto end; + + /* + * If we detect that a call_rcu is pending for this marker, + * make sure it's executed now. + */ + if (entry->rcu_pending) + rcu_barrier_sched(); + old = marker_entry_add_probe(entry, probe, probe_private); + if (IS_ERR(old)) { + ret = PTR_ERR(old); + goto end; + } + mutex_unlock(&markers_mutex); + marker_update_probes(); /* may update entry */ + mutex_lock(&markers_mutex); + entry = get_marker(name); + WARN_ON(!entry); + if (entry->rcu_pending) + rcu_barrier_sched(); + entry->oldptr = old; + entry->rcu_pending = 1; + /* write rcu_pending before calling the RCU callback */ + smp_wmb(); + call_rcu_sched(&entry->rcu, free_old_closure); +end: + mutex_unlock(&markers_mutex); + return ret; +} +EXPORT_SYMBOL_GPL(marker_probe_register); + +/** + * marker_probe_unregister - Disconnect a probe from a marker + * @name: marker name + * @probe: probe function pointer + * @probe_private: probe private data + * + * Returns the private data given to marker_probe_register, or an ERR_PTR(). + * We do not need to call a synchronize_sched to make sure the probes have + * finished running before doing a module unload, because the module unload + * itself uses stop_machine(), which insures that every preempt disabled section + * have finished. + */ +int marker_probe_unregister(const char *name, + marker_probe_func *probe, void *probe_private) +{ + struct marker_entry *entry; + struct marker_probe_closure *old; + int ret = -ENOENT; + + mutex_lock(&markers_mutex); + entry = get_marker(name); + if (!entry) + goto end; + if (entry->rcu_pending) + rcu_barrier_sched(); + old = marker_entry_remove_probe(entry, probe, probe_private); + mutex_unlock(&markers_mutex); + marker_update_probes(); /* may update entry */ + mutex_lock(&markers_mutex); + entry = get_marker(name); + if (!entry) + goto end; + if (entry->rcu_pending) + rcu_barrier_sched(); + entry->oldptr = old; + entry->rcu_pending = 1; + /* write rcu_pending before calling the RCU callback */ + smp_wmb(); + call_rcu_sched(&entry->rcu, free_old_closure); + remove_marker(name); /* Ignore busy error message */ + ret = 0; +end: + mutex_unlock(&markers_mutex); + return ret; +} +EXPORT_SYMBOL_GPL(marker_probe_unregister); + +static struct marker_entry * +get_marker_from_private_data(marker_probe_func *probe, void *probe_private) +{ + struct marker_entry *entry; + unsigned int i; + struct hlist_head *head; + struct hlist_node *node; + + for (i = 0; i < MARKER_TABLE_SIZE; i++) { + head = &marker_table[i]; + hlist_for_each_entry(entry, node, head, hlist) { + if (!entry->ptype) { + if (entry->single.func == probe + && entry->single.probe_private + == probe_private) + return entry; + } else { + struct marker_probe_closure *closure; + closure = entry->multi; + for (i = 0; closure[i].func; i++) { + if (closure[i].func == probe && + closure[i].probe_private + == probe_private) + return entry; + } + } + } + } + return NULL; +} + +/** + * marker_probe_unregister_private_data - Disconnect a probe from a marker + * @probe: probe function + * @probe_private: probe private data + * + * Unregister a probe by providing the registered private data. + * Only removes the first marker found in hash table. + * Return 0 on success or error value. + * We do not need to call a synchronize_sched to make sure the probes have + * finished running before doing a module unload, because the module unload + * itself uses stop_machine(), which insures that every preempt disabled section + * have finished. + */ +int marker_probe_unregister_private_data(marker_probe_func *probe, + void *probe_private) +{ + struct marker_entry *entry; + int ret = 0; + struct marker_probe_closure *old; + + mutex_lock(&markers_mutex); + entry = get_marker_from_private_data(probe, probe_private); + if (!entry) { + ret = -ENOENT; + goto end; + } + if (entry->rcu_pending) + rcu_barrier_sched(); + old = marker_entry_remove_probe(entry, NULL, probe_private); + mutex_unlock(&markers_mutex); + marker_update_probes(); /* may update entry */ + mutex_lock(&markers_mutex); + entry = get_marker_from_private_data(probe, probe_private); + WARN_ON(!entry); + if (entry->rcu_pending) + rcu_barrier_sched(); + entry->oldptr = old; + entry->rcu_pending = 1; + /* write rcu_pending before calling the RCU callback */ + smp_wmb(); + call_rcu_sched(&entry->rcu, free_old_closure); + remove_marker(entry->name); /* Ignore busy error message */ +end: + mutex_unlock(&markers_mutex); + return ret; +} +EXPORT_SYMBOL_GPL(marker_probe_unregister_private_data); + +/** + * marker_get_private_data - Get a marker's probe private data + * @name: marker name + * @probe: probe to match + * @num: get the nth matching probe's private data + * + * Returns the nth private data pointer (starting from 0) matching, or an + * ERR_PTR. + * Returns the private data pointer, or an ERR_PTR. + * The private data 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_private_data(const char *name, marker_probe_func *probe, + int num) +{ + 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 i; + + head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)]; + hlist_for_each_entry(e, node, head, hlist) { + if (!strcmp(name, e->name)) { + if (!e->ptype) { + if (num == 0 && e->single.func == probe) + return e->single.probe_private; + else + break; + } else { + struct marker_probe_closure *closure; + int match = 0; + closure = e->multi; + for (i = 0; closure[i].func; i++) { + if (closure[i].func != probe) + continue; + if (match++ == num) + return closure[i].probe_private; + } + } + } + } + return ERR_PTR(-ENOENT); +} +EXPORT_SYMBOL_GPL(marker_get_private_data); |
