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Subject[PATCH tip/tracing/markers] new probes manager

this patch use a new probes manager for marker.

the most important benefit of this patch is:
1) smp_rmb() is removed from the critical path. as we know rmb()
is very expensive.

the other benefits:
2) Now, unused memory is handled by struct marker_probes.

old code use these three field to handle unused memory.
struct marker_entry {
...
struct rcu_head rcu;
void *oldptr;
int rcu_pending;
...
};
in this way, unused memory is handled by struct marker_entry.
it bring reenter bug(it was fixed) and marker.c is filled
full of ".*rcu.*" code statements. this patch remove all these.

3) use new probes manager, and remove the "single optimization",
and remove hundreds of codes. "single optimization" indeed
speedup register/unregister side, but it brings smp_rmb()
in the critical path, and brings a lots of code.

and the size of struct marker is reduced. struct marker's
memory is pre-allocated by compiler. this fix will save
this memory.

about struct marker.state and immediate value:
4) struct marker.state is removed, for it equals to
struct marker.multi != NULL
and struct marker.multi can use immediate value also in future.


Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
include/linux/marker.h | 12 -
kernel/marker.c | 552 +++++++++++++------------------------------------
2 files changed, 150 insertions(+), 414 deletions(-)
diff --git a/include/linux/marker.h b/include/linux/marker.h
index 4aca94a..179c59a 100644
--- a/include/linux/marker.h
+++ b/include/linux/marker.h
@@ -43,11 +43,8 @@ struct marker {
const char *format; /* Marker format string, describing the
* variable argument list.
*/
- char state; /* Marker state. */
- char ptype; /* probe type : 0 : single, 1 : multi */
- /* Probe wrapper */
+
void (*call)(const struct marker *mdata, void *call_private, ...);
- struct marker_probe_closure single;
struct marker_probe_closure *multi;
} __attribute__((aligned(8)));

@@ -72,10 +69,9 @@ struct marker {
static struct marker __mark_##name \
__attribute__((section("__markers"), aligned(8))) = \
{ __mstrtab_##name, &__mstrtab_##name[sizeof(#name)], \
- 0, 0, marker_probe_cb, \
- { __mark_empty_function, NULL}, NULL }; \
+ marker_probe_cb, NULL }; \
__mark_check_format(format, ## args); \
- if (unlikely(__mark_##name.state)) { \
+ if (unlikely(__mark_##name.multi)) { \
(*__mark_##name.call) \
(&__mark_##name, call_private, ## args);\
} \
@@ -133,8 +129,6 @@ static inline void __printf(1, 2) ___mark_check_format(const char *fmt, ...)
___mark_check_format(format, ## args); \
} while (0)

-extern marker_probe_func __mark_empty_function;
-
extern void marker_probe_cb(const struct marker *mdata,
void *call_private, ...);

diff --git a/kernel/marker.c b/kernel/marker.c
index 2898b64..dee5bd3 100644
--- a/kernel/marker.c
+++ b/kernel/marker.c
@@ -1,5 +1,6 @@
/*
* Copyright (C) 2007 Mathieu Desnoyers
+ * Copyright (C) 2008 Lai Jiangshan
*
* 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
@@ -55,89 +56,32 @@ static struct hlist_head marker_table[MARKER_TABLE_SIZE];
*/
struct marker_entry {
struct hlist_node hlist;
- char *format;
+ const 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;
+ int refcount; /* Number of probes */
unsigned char format_allocated:1;
- char name[0]; /* Contains name'\0'format'\0' */
+ const char name[0]; /* Contains name'\0'format'\0' */
};

/**
- * __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.
+ * marker_probe_cb - Call probes with the variable argument list
* @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;
+ struct marker_probe_closure *multi;

- /*
- * 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;
+ /* reload mdata->multi again with rcu_read_lock_sched() held. */
+ multi = rcu_dereference(mdata->multi);
+ /* recheck multi after reload */
+ if (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,
@@ -149,48 +93,26 @@ void marker_probe_cb(const struct marker *mdata, void *call_private, ...)
}
EXPORT_SYMBOL_GPL(marker_probe_cb);

-/*
- * marker_probe_cb Callback that does not prepare the variable argument list.
+/**
+ * marker_probe_cb_noarg - Call probes without 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".
*/
-static void marker_probe_cb_noarg(const struct marker *mdata, void *call_private, ...)
+static void marker_probe_cb_noarg(const struct marker *mdata,
+ void *call_private, ...)
{
- va_list args; /* not initialized */
- char ptype;
+ va_list args;
+ struct marker_probe_closure *multi;

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;
+ /* reload mdata->multi again with rcu_read_lock_sched() held. */
+ multi = rcu_dereference(mdata->multi);
+ /* recheck multi after reload */
+ if (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);
@@ -198,14 +120,35 @@ static void marker_probe_cb_noarg(const struct marker *mdata, void *call_private
rcu_read_unlock_sched();
}

-static void free_old_closure(struct rcu_head *head)
+struct marker_probes {
+ struct rcu_head rcu;
+ struct marker_probe_closure multi[0];
+};
+
+static inline struct marker_probe_closure *allocate_probe_closure(int count)
+{
+ struct marker_probes *p;
+ p = kmalloc(count * sizeof(struct marker_probe_closure)
+ + sizeof(struct marker_probes), GFP_KERNEL);
+ if (!p)
+ return NULL;
+ return p->multi;
+}
+
+static void rcu_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;
+ struct marker_probes *probes = container_of(head,
+ struct marker_probes, rcu);
+ kfree(probes);
+}
+
+static inline void release_probe_closure(struct marker_probe_closure *old)
+{
+ if (old) {
+ struct marker_probes *probes = container_of(old,
+ struct marker_probes, multi[0]);
+ call_rcu(&probes->rcu, rcu_free_old_closure);
+ }
}

static void debug_print_probes(struct marker_entry *entry)
@@ -215,69 +158,40 @@ static void debug_print_probes(struct marker_entry *entry)
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);
- }
+ for (i = 0; i < entry->refcount; 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;
+ int nr_probes = entry->refcount, i;
struct marker_probe_closure *old, *new;

- WARN_ON(!probe);
+ if (!probe)
+ return ERR_PTR(-EINVAL);

debug_print_probes(entry);
old = entry->multi;
- if (!entry->ptype) {
- if (entry->single.func == probe &&
- entry->single.probe_private == probe_private)
+ for (i = 0; i < nr_probes; i++)
+ if (old[i].func == probe
+ && old[i].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)
+ new = allocate_probe_closure(nr_probes + 2);
+ if (!new)
return ERR_PTR(-ENOMEM);
- if (!old)
- new[0] = entry->single;
- else
- memcpy(new, old,
- nr_probes * sizeof(struct marker_probe_closure));
+ memcpy(new, old, nr_probes * sizeof(struct marker_probe_closure));
new[nr_probes].func = probe;
new[nr_probes].probe_private = probe_private;
+ new[nr_probes + 1].func = NULL;
+ new[nr_probes + 1].probe_private = NULL;
entry->refcount = nr_probes + 1;
entry->multi = new;
- entry->ptype = 1;
debug_print_probes(entry);
return old;
}
@@ -286,60 +200,33 @@ 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;
+ int nr_probes = entry->refcount, 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++;
- }
+ old = entry->multi;
+ for (i = 0; i < nr_probes; i++) {
+ if ((!probe || old[i].func == probe)
+ && old[i].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;
+ entry->multi = NULL;
} 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)
+ new = allocate_probe_closure(nr_probes - nr_del + 1);
+ if (!new)
return ERR_PTR(-ENOMEM);
- for (i = 0; old[i].func; i++)
+ for (i = 0; i < nr_probes; i++)
if ((probe && old[i].func != probe) ||
old[i].probe_private != probe_private)
new[j++] = old[i];
+ new[nr_probes - nr_del].func = NULL;
+ new[nr_probes - nr_del].probe_private = NULL;
entry->refcount = nr_probes - nr_del;
- entry->ptype = 1;
entry->multi = new;
}
debug_print_probes(entry);
@@ -358,7 +245,7 @@ static struct marker_entry *get_marker(const char *name)
struct marker_entry *e;
u32 hash = jhash(name, strlen(name), 0);

- head = &marker_table[hash & ((1 << MARKER_HASH_BITS)-1)];
+ head = &marker_table[hash & (MARKER_TABLE_SIZE - 1)];
hlist_for_each_entry(e, node, head, hlist) {
if (!strcmp(name, e->name))
return e;
@@ -373,22 +260,14 @@ static struct marker_entry *get_marker(const char *name)
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);
+ u32 hash = jhash(name, name_len - 1, 0);

+ head = &marker_table[hash & (MARKER_TABLE_SIZE - 1)];
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.
@@ -397,10 +276,10 @@ static struct marker_entry *add_marker(const char *name, const char *format)
GFP_KERNEL);
if (!e)
return ERR_PTR(-ENOMEM);
- memcpy(&e->name[0], name, name_len);
+ memcpy((void *)&e->name[0], name, name_len);
if (format) {
e->format = &e->name[name_len];
- memcpy(e->format, format, format_len);
+ memcpy((void *)e->format, format, format_len);
if (strcmp(e->format, MARK_NOARGS) == 0)
e->call = marker_probe_cb_noarg;
else
@@ -411,13 +290,9 @@ static struct marker_entry *add_marker(const char *name, const char *format)
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->format_allocated = 0;
e->refcount = 0;
- e->rcu_pending = 0;
hlist_add_head(&e->hlist, head);
return e;
}
@@ -426,38 +301,16 @@ static struct marker_entry *add_marker(const char *name, const char *format)
* Remove the marker from the marker hash table. Must be called with mutex_lock
* held.
*/
-static int remove_marker(const char *name)
+static inline void remove_marker(struct marker_entry *entry)
{
- 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);
- if (e->format_allocated)
- kfree(e->format);
- /* Make sure the call_rcu has been executed */
- if (e->rcu_pending)
- rcu_barrier_sched();
- kfree(e);
- return 0;
+ hlist_del(&entry->hlist);
+ if (entry->format_allocated)
+ kfree(entry->format);
+ kfree(entry);
}

/*
- * Set the mark_entry format to the format found in the element.
+ * Set the mark_entry format to the format.
*/
static int marker_set_format(struct marker_entry *entry, const char *format)
{
@@ -466,6 +319,11 @@ static int marker_set_format(struct marker_entry *entry, const char *format)
return -ENOMEM;
entry->format_allocated = 1;

+ if (strcmp(entry->format, MARK_NOARGS) == 0)
+ entry->call = marker_probe_cb_noarg;
+ else
+ entry->call = marker_probe_cb;
+
trace_mark(core_marker_format, "name %s format %s",
entry->name, entry->format);
return 0;
@@ -474,8 +332,7 @@ static int marker_set_format(struct marker_entry *entry, const char *format)
/*
* Sets the probe callback corresponding to one marker.
*/
-static int set_marker(struct marker_entry *entry, struct marker *elem,
- int active)
+static int set_marker(struct marker_entry *entry, struct marker *elem)
{
int ret;
WARN_ON(strcmp(entry->name, elem->name) != 0);
@@ -503,56 +360,18 @@ static int set_marker(struct marker_entry *entry, struct marker *elem,
* 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)
+static inline 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.
- */
+ rcu_assign_pointer(elem->multi, NULL);
}

/**
@@ -562,8 +381,7 @@ static void disable_marker(struct marker *elem)
*
* Updates the probe callback corresponding to a range of markers.
*/
-void marker_update_probe_range(struct marker *begin,
- struct marker *end)
+void marker_update_probe_range(struct marker *begin, struct marker *end)
{
struct marker *iter;
struct marker_entry *mark_entry;
@@ -572,7 +390,7 @@ void marker_update_probe_range(struct marker *begin,
for (iter = begin; iter < end; iter++) {
mark_entry = get_marker(iter->name);
if (mark_entry) {
- set_marker(mark_entry, iter, !!mark_entry->refcount);
+ set_marker(mark_entry, iter);
/*
* ignore error, continue
*/
@@ -585,20 +403,6 @@ void marker_update_probe_range(struct marker *begin,

/*
* 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)
{
@@ -638,35 +442,19 @@ int marker_probe_register(const char *name, const char *format,
else if (strcmp(entry->format, format))
ret = -EPERM;
}
- if (ret)
- goto end;
+ if (ret) {
+ mutex_unlock(&markers_mutex);
+ return ret;
+ }

- /*
- * 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);
+ if (old && IS_ERR(old))
+ return PTR_ERR(old);
+
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;
+ release_probe_closure(old);
+ return 0;
}
EXPORT_SYMBOL_GPL(marker_probe_register);

@@ -677,43 +465,32 @@ EXPORT_SYMBOL_GPL(marker_probe_register);
* @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();
+ if (!entry) {
+ mutex_unlock(&markers_mutex);
+ return -ENOENT;
+ }
+
old = marker_entry_remove_probe(entry, probe, probe_private);
+ if (!entry->refcount)
+ remove_marker(entry);
+
mutex_unlock(&markers_mutex);
+ if (old && IS_ERR(old))
+ return PTR_ERR(old);
+
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;
+ release_probe_closure(old);
+
+ return 0;
}
EXPORT_SYMBOL_GPL(marker_probe_unregister);

@@ -728,20 +505,13 @@ get_marker_from_private_data(marker_probe_func *probe, void *probe_private)
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
+ struct marker_probe_closure *closure;
+ closure = entry->multi;
+ for (i = 0; i < entry->refcount; i++) {
+ if (closure[i].func == probe &&
+ closure[i].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;
- }
}
}
}
@@ -756,43 +526,32 @@ get_marker_from_private_data(marker_probe_func *probe, void *probe_private)
* 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;
+ mutex_unlock(&markers_mutex);
+ return -ENOENT;
}
- if (entry->rcu_pending)
- rcu_barrier_sched();
+
old = marker_entry_remove_probe(entry, NULL, probe_private);
+ if (!entry->refcount)
+ remove_marker(entry);
+
mutex_unlock(&markers_mutex);
+ if (old && IS_ERR(old))
+ return PTR_ERR(old);
+
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;
+ release_probe_closure(old);
+
+ return 0;
}
EXPORT_SYMBOL_GPL(marker_probe_unregister_private_data);

@@ -804,7 +563,6 @@ EXPORT_SYMBOL_GPL(marker_probe_unregister_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.
@@ -812,31 +570,15 @@ EXPORT_SYMBOL_GPL(marker_probe_unregister_private_data);
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 {
- 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;
- }
- }
- break;
+ struct marker_entry *e = get_marker(name);
+ if (e) {
+ struct marker_probe_closure *closure = e->multi;
+ int match = 0, i;
+ for (i = 0; i < e->refcount; i++) {
+ if (closure[i].func != probe)
+ continue;
+ if (match++ == num)
+ return closure[i].probe_private;
}
}
return ERR_PTR(-ENOENT);



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