[v3->v4]:
1. use "bool enabled = is_trace_uprobe_enabled(tu);", suggested by Oleg.
2. use list_add_tail_rcu instead of list_add_rcu, suggested by Masami.
3. fix the error handling in probe_event_enable, found by Srikar.
-------------------
Support multi-buffer on uprobe-based dynamic events by
using ftrace_event_file.
This patch is based kprobe-based dynamic events multibuffer
support work initially, commited by Masami(commit 41a7dd420c),
but revised as below:
Oleg changed the kprobe-based multibuffer design from
array-pointers of ftrace_event_file into simple list,
so this patch also change to the list degisn.
rcu_read_lock/unlock added into uprobe_trace_func/uretprobe_trace_func,
to synchronize with ftrace_event_file list add and delete.
Even though we allow multi-uprobes instances now,
but TP_FLAG_PROFILE/TP_FLAG_TRACE are still mutually exclusive
in probe_event_enable currently, this means we cannot allow
one user is using uprobe-tracer, and another user is using
perf-probe on same uprobe concurrently.
(Perhaps this will be fix in future, kprobe dont't have this
limitation now)
Signed-off-by: zhangwei(Jovi) <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Srikar Dronamraju <[email protected]>
---
kernel/trace/trace_uprobe.c | 123 +++++++++++++++++++++++++++++++++++--------
1 file changed, 101 insertions(+), 22 deletions(-)
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 32494fb0..760d4ed 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -53,6 +53,7 @@ struct trace_uprobe {
struct list_head list;
struct ftrace_event_class class;
struct ftrace_event_call call;
+ struct list_head files;
struct trace_uprobe_filter filter;
struct uprobe_consumer consumer;
struct inode *inode;
@@ -65,6 +66,11 @@ struct trace_uprobe {
struct probe_arg args[];
};
+struct event_file_link {
+ struct ftrace_event_file *file;
+ struct list_head list;
+};
+
#define SIZEOF_TRACE_UPROBE(n) \
(offsetof(struct trace_uprobe, args) + \
(sizeof(struct probe_arg) * (n)))
@@ -124,6 +130,7 @@ alloc_trace_uprobe(const char *group, const char *event, int nargs, bool is_ret)
goto error;
INIT_LIST_HEAD(&tu->list);
+ INIT_LIST_HEAD(&tu->files);
tu->consumer.handler = uprobe_dispatcher;
if (is_ret)
tu->consumer.ret_handler = uretprobe_dispatcher;
@@ -511,7 +518,8 @@ static const struct file_operations uprobe_profile_ops = {
};
static void uprobe_trace_print(struct trace_uprobe *tu,
- unsigned long func, struct pt_regs *regs)
+ unsigned long func, struct pt_regs *regs,
+ struct ftrace_event_file *ftrace_file)
{
struct uprobe_trace_entry_head *entry;
struct ring_buffer_event *event;
@@ -520,9 +528,12 @@ static void uprobe_trace_print(struct trace_uprobe *tu,
int size, i;
struct ftrace_event_call *call = &tu->call;
+ WARN_ON(call != ftrace_file->event_call);
+
size = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
- event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
- size + tu->size, 0, 0);
+ event = trace_event_buffer_lock_reserve(&buffer, ftrace_file,
+ call->event.type,
+ size + tu->size, 0, 0);
if (!event)
return;
@@ -546,15 +557,28 @@ static void uprobe_trace_print(struct trace_uprobe *tu,
/* uprobe handler */
static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs)
{
- if (!is_ret_probe(tu))
- uprobe_trace_print(tu, 0, regs);
+ struct event_file_link *link;
+
+ if (is_ret_probe(tu))
+ return 0;
+
+ rcu_read_lock();
+ list_for_each_entry(link, &tu->files, list)
+ uprobe_trace_print(tu, 0, regs, link->file);
+ rcu_read_unlock();
+
return 0;
}
static void uretprobe_trace_func(struct trace_uprobe *tu, unsigned long func,
struct pt_regs *regs)
{
- uprobe_trace_print(tu, func, regs);
+ struct event_file_link *link;
+
+ rcu_read_lock();
+ list_for_each_entry(link, &tu->files, list)
+ uprobe_trace_print(tu, func, regs, link->file);
+ rcu_read_unlock();
}
/* Event entry printers */
@@ -605,33 +629,87 @@ typedef bool (*filter_func_t)(struct uprobe_consumer *self,
struct mm_struct *mm);
static int
-probe_event_enable(struct trace_uprobe *tu, int flag, filter_func_t filter)
+probe_event_enable(struct trace_uprobe *tu, struct ftrace_event_file *file,
+ filter_func_t filter)
{
+ bool enabled = is_trace_uprobe_enabled(tu);
+ struct event_file_link *link;
int ret = 0;
- if (is_trace_uprobe_enabled(tu))
- return -EINTR;
+ if (file) {
+ if (tu->flags & TP_FLAG_PROFILE)
+ return -EINTR;
+
+ link = kmalloc(sizeof(*link), GFP_KERNEL);
+ if (!link)
+ return -ENOMEM;
+
+ link->file = file;
+ list_add_tail_rcu(&link->list, &tu->files);
+
+ tu->flags |= TP_FLAG_TRACE;
+ } else {
+ if (tu->flags & TP_FLAG_TRACE)
+ return -EINTR;
+
+ tu->flags |= TP_FLAG_PROFILE;
+ }
WARN_ON(!uprobe_filter_is_empty(&tu->filter));
- tu->flags |= flag;
- tu->consumer.filter = filter;
- ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
- if (ret)
- tu->flags &= ~flag;
+ /* we cannot call uprobe_register twice for same tu */
+ if (!enabled) {
+ tu->consumer.filter = filter;
+ ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
+ }
+
+ if (ret) {
+ if (file) {
+ list_del_rcu(&link->list);
+ kfree(link);
+ tu->flags &= ~TP_FLAG_TRACE;
+ } else
+ tu->flags &= ~TP_FLAG_PROFILE;
+ }
return ret;
}
-static void probe_event_disable(struct trace_uprobe *tu, int flag)
+static struct event_file_link *
+find_event_file_link(struct trace_uprobe *tu, struct ftrace_event_file *file)
{
- if (!is_trace_uprobe_enabled(tu))
- return;
+ struct event_file_link *link;
+
+ list_for_each_entry(link, &tu->files, list)
+ if (link->file == file)
+ return link;
+
+ return NULL;
+}
+
+static void
+probe_event_disable(struct trace_uprobe *tu, struct ftrace_event_file *file)
+{
+ if (file) {
+ struct event_file_link *link;
+
+ link = find_event_file_link(tu, file);
+ if (!link)
+ return;
+
+ list_del_rcu(&link->list);
+ /* synchronize with uprobe_trace_func/uretprobe_trace_func */
+ synchronize_sched();
+ kfree(link);
+
+ if (!list_empty(&tu->files))
+ return;
+ }
WARN_ON(!uprobe_filter_is_empty(&tu->filter));
uprobe_unregister(tu->inode, tu->offset, &tu->consumer);
- tu->flags &= ~flag;
+ tu->flags &= file ? ~TP_FLAG_TRACE : ~TP_FLAG_PROFILE;
}
static int uprobe_event_define_fields(struct ftrace_event_call *event_call)
@@ -867,21 +945,22 @@ static
int trace_uprobe_register(struct ftrace_event_call *event, enum trace_reg type, void *data)
{
struct trace_uprobe *tu = event->data;
+ struct ftrace_event_file *file = data;
switch (type) {
case TRACE_REG_REGISTER:
- return probe_event_enable(tu, TP_FLAG_TRACE, NULL);
+ return probe_event_enable(tu, file, NULL);
case TRACE_REG_UNREGISTER:
- probe_event_disable(tu, TP_FLAG_TRACE);
+ probe_event_disable(tu, file);
return 0;
#ifdef CONFIG_PERF_EVENTS
case TRACE_REG_PERF_REGISTER:
- return probe_event_enable(tu, TP_FLAG_PROFILE, uprobe_perf_filter);
+ return probe_event_enable(tu, NULL, uprobe_perf_filter);
case TRACE_REG_PERF_UNREGISTER:
- probe_event_disable(tu, TP_FLAG_PROFILE);
+ probe_event_disable(tu, NULL);
return 0;
case TRACE_REG_PERF_OPEN:
--
1.7.9.7
On Sat, 2013-06-29 at 15:51 +0800, zhangwei(Jovi) wrote:
> [v3->v4]:
> 1. use "bool enabled = is_trace_uprobe_enabled(tu);", suggested by Oleg.
> 2. use list_add_tail_rcu instead of list_add_rcu, suggested by Masami.
> 3. fix the error handling in probe_event_enable, found by Srikar.
Is this the final patch?
Masami, can you give your reviewed by (Oleg and Srikar, feel free to add
your tags either).
Also, the origin was a two patch set. Is the second patch needed?
Thanks,
-- Steve
>
> -------------------
>
> Support multi-buffer on uprobe-based dynamic events by
> using ftrace_event_file.
>
> This patch is based kprobe-based dynamic events multibuffer
> support work initially, commited by Masami(commit 41a7dd420c),
> but revised as below:
>
> Oleg changed the kprobe-based multibuffer design from
> array-pointers of ftrace_event_file into simple list,
> so this patch also change to the list degisn.
>
> rcu_read_lock/unlock added into uprobe_trace_func/uretprobe_trace_func,
> to synchronize with ftrace_event_file list add and delete.
>
> Even though we allow multi-uprobes instances now,
> but TP_FLAG_PROFILE/TP_FLAG_TRACE are still mutually exclusive
> in probe_event_enable currently, this means we cannot allow
> one user is using uprobe-tracer, and another user is using
> perf-probe on same uprobe concurrently.
> (Perhaps this will be fix in future, kprobe dont't have this
> limitation now)
>
> Signed-off-by: zhangwei(Jovi) <[email protected]>
> Cc: Masami Hiramatsu <[email protected]>
> Cc: Frederic Weisbecker <[email protected]>
> Cc: Oleg Nesterov <[email protected]>
> Cc: Srikar Dronamraju <[email protected]>
> ---
> kernel/trace/trace_uprobe.c | 123 +++++++++++++++++++++++++++++++++++--------
> 1 file changed, 101 insertions(+), 22 deletions(-)
>
> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> index 32494fb0..760d4ed 100644
> --- a/kernel/trace/trace_uprobe.c
> +++ b/kernel/trace/trace_uprobe.c
> @@ -53,6 +53,7 @@ struct trace_uprobe {
> struct list_head list;
> struct ftrace_event_class class;
> struct ftrace_event_call call;
> + struct list_head files;
> struct trace_uprobe_filter filter;
> struct uprobe_consumer consumer;
> struct inode *inode;
> @@ -65,6 +66,11 @@ struct trace_uprobe {
> struct probe_arg args[];
> };
>
> +struct event_file_link {
> + struct ftrace_event_file *file;
> + struct list_head list;
> +};
> +
> #define SIZEOF_TRACE_UPROBE(n) \
> (offsetof(struct trace_uprobe, args) + \
> (sizeof(struct probe_arg) * (n)))
> @@ -124,6 +130,7 @@ alloc_trace_uprobe(const char *group, const char *event, int nargs, bool is_ret)
> goto error;
>
> INIT_LIST_HEAD(&tu->list);
> + INIT_LIST_HEAD(&tu->files);
> tu->consumer.handler = uprobe_dispatcher;
> if (is_ret)
> tu->consumer.ret_handler = uretprobe_dispatcher;
> @@ -511,7 +518,8 @@ static const struct file_operations uprobe_profile_ops = {
> };
>
> static void uprobe_trace_print(struct trace_uprobe *tu,
> - unsigned long func, struct pt_regs *regs)
> + unsigned long func, struct pt_regs *regs,
> + struct ftrace_event_file *ftrace_file)
> {
> struct uprobe_trace_entry_head *entry;
> struct ring_buffer_event *event;
> @@ -520,9 +528,12 @@ static void uprobe_trace_print(struct trace_uprobe *tu,
> int size, i;
> struct ftrace_event_call *call = &tu->call;
>
> + WARN_ON(call != ftrace_file->event_call);
> +
> size = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
> - event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
> - size + tu->size, 0, 0);
> + event = trace_event_buffer_lock_reserve(&buffer, ftrace_file,
> + call->event.type,
> + size + tu->size, 0, 0);
> if (!event)
> return;
>
> @@ -546,15 +557,28 @@ static void uprobe_trace_print(struct trace_uprobe *tu,
> /* uprobe handler */
> static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs)
> {
> - if (!is_ret_probe(tu))
> - uprobe_trace_print(tu, 0, regs);
> + struct event_file_link *link;
> +
> + if (is_ret_probe(tu))
> + return 0;
> +
> + rcu_read_lock();
> + list_for_each_entry(link, &tu->files, list)
> + uprobe_trace_print(tu, 0, regs, link->file);
> + rcu_read_unlock();
> +
> return 0;
> }
>
> static void uretprobe_trace_func(struct trace_uprobe *tu, unsigned long func,
> struct pt_regs *regs)
> {
> - uprobe_trace_print(tu, func, regs);
> + struct event_file_link *link;
> +
> + rcu_read_lock();
> + list_for_each_entry(link, &tu->files, list)
> + uprobe_trace_print(tu, func, regs, link->file);
> + rcu_read_unlock();
> }
>
> /* Event entry printers */
> @@ -605,33 +629,87 @@ typedef bool (*filter_func_t)(struct uprobe_consumer *self,
> struct mm_struct *mm);
>
> static int
> -probe_event_enable(struct trace_uprobe *tu, int flag, filter_func_t filter)
> +probe_event_enable(struct trace_uprobe *tu, struct ftrace_event_file *file,
> + filter_func_t filter)
> {
> + bool enabled = is_trace_uprobe_enabled(tu);
> + struct event_file_link *link;
> int ret = 0;
>
> - if (is_trace_uprobe_enabled(tu))
> - return -EINTR;
> + if (file) {
> + if (tu->flags & TP_FLAG_PROFILE)
> + return -EINTR;
> +
> + link = kmalloc(sizeof(*link), GFP_KERNEL);
> + if (!link)
> + return -ENOMEM;
> +
> + link->file = file;
> + list_add_tail_rcu(&link->list, &tu->files);
> +
> + tu->flags |= TP_FLAG_TRACE;
> + } else {
> + if (tu->flags & TP_FLAG_TRACE)
> + return -EINTR;
> +
> + tu->flags |= TP_FLAG_PROFILE;
> + }
>
> WARN_ON(!uprobe_filter_is_empty(&tu->filter));
>
> - tu->flags |= flag;
> - tu->consumer.filter = filter;
> - ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
> - if (ret)
> - tu->flags &= ~flag;
> + /* we cannot call uprobe_register twice for same tu */
> + if (!enabled) {
> + tu->consumer.filter = filter;
> + ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
> + }
> +
> + if (ret) {
> + if (file) {
> + list_del_rcu(&link->list);
> + kfree(link);
> + tu->flags &= ~TP_FLAG_TRACE;
> + } else
> + tu->flags &= ~TP_FLAG_PROFILE;
> + }
>
> return ret;
> }
>
> -static void probe_event_disable(struct trace_uprobe *tu, int flag)
> +static struct event_file_link *
> +find_event_file_link(struct trace_uprobe *tu, struct ftrace_event_file *file)
> {
> - if (!is_trace_uprobe_enabled(tu))
> - return;
> + struct event_file_link *link;
> +
> + list_for_each_entry(link, &tu->files, list)
> + if (link->file == file)
> + return link;
> +
> + return NULL;
> +}
> +
> +static void
> +probe_event_disable(struct trace_uprobe *tu, struct ftrace_event_file *file)
> +{
> + if (file) {
> + struct event_file_link *link;
> +
> + link = find_event_file_link(tu, file);
> + if (!link)
> + return;
> +
> + list_del_rcu(&link->list);
> + /* synchronize with uprobe_trace_func/uretprobe_trace_func */
> + synchronize_sched();
> + kfree(link);
> +
> + if (!list_empty(&tu->files))
> + return;
> + }
>
> WARN_ON(!uprobe_filter_is_empty(&tu->filter));
>
> uprobe_unregister(tu->inode, tu->offset, &tu->consumer);
> - tu->flags &= ~flag;
> + tu->flags &= file ? ~TP_FLAG_TRACE : ~TP_FLAG_PROFILE;
> }
>
> static int uprobe_event_define_fields(struct ftrace_event_call *event_call)
> @@ -867,21 +945,22 @@ static
> int trace_uprobe_register(struct ftrace_event_call *event, enum trace_reg type, void *data)
> {
> struct trace_uprobe *tu = event->data;
> + struct ftrace_event_file *file = data;
>
> switch (type) {
> case TRACE_REG_REGISTER:
> - return probe_event_enable(tu, TP_FLAG_TRACE, NULL);
> + return probe_event_enable(tu, file, NULL);
>
> case TRACE_REG_UNREGISTER:
> - probe_event_disable(tu, TP_FLAG_TRACE);
> + probe_event_disable(tu, file);
> return 0;
>
> #ifdef CONFIG_PERF_EVENTS
> case TRACE_REG_PERF_REGISTER:
> - return probe_event_enable(tu, TP_FLAG_PROFILE, uprobe_perf_filter);
> + return probe_event_enable(tu, NULL, uprobe_perf_filter);
>
> case TRACE_REG_PERF_UNREGISTER:
> - probe_event_disable(tu, TP_FLAG_PROFILE);
> + probe_event_disable(tu, NULL);
> return 0;
>
> case TRACE_REG_PERF_OPEN:
On 06/29, zhangwei(Jovi) wrote:
>
> [v3->v4]:
I am wondering how much you will hate me if I suggest to make v5 ;)
But look, imho probe_event_enable() looks a bit more confusing than
it needs.
> -probe_event_enable(struct trace_uprobe *tu, int flag, filter_func_t filter)
> +probe_event_enable(struct trace_uprobe *tu, struct ftrace_event_file *file,
> + filter_func_t filter)
> {
> + bool enabled = is_trace_uprobe_enabled(tu);
> + struct event_file_link *link;
> int ret = 0;
Unnecessary initialization.
> - if (is_trace_uprobe_enabled(tu))
> - return -EINTR;
> + if (file) {
> + if (tu->flags & TP_FLAG_PROFILE)
> + return -EINTR;
> +
> + link = kmalloc(sizeof(*link), GFP_KERNEL);
> + if (!link)
> + return -ENOMEM;
> +
> + link->file = file;
> + list_add_tail_rcu(&link->list, &tu->files);
> +
> + tu->flags |= TP_FLAG_TRACE;
> + } else {
> + if (tu->flags & TP_FLAG_TRACE)
> + return -EINTR;
> +
> + tu->flags |= TP_FLAG_PROFILE;
> + }
>
> WARN_ON(!uprobe_filter_is_empty(&tu->filter));
>
> - tu->flags |= flag;
> - tu->consumer.filter = filter;
> - ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
> - if (ret)
> - tu->flags &= ~flag;
> + /* we cannot call uprobe_register twice for same tu */
The comment is confusing, I'd suggest to simply remove it.
Yes, we can't do uprobe_register() twice as we already discussed.
But it is not that we "can't", we simply do not need this if uprobe
was already created.
> + if (!enabled) {
> + tu->consumer.filter = filter;
> + ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
> + }
> +
> + if (ret) {
> + if (file) {
> + list_del_rcu(&link->list);
I won't insist, but _rcu is not needed in this case. Again, this looks
a bit confusing, as if we expect that some rcu reader can ever see this
entry. But this is not true and we are going to just kfree it without
synchronize_rcu().
> + kfree(link);
> + tu->flags &= ~TP_FLAG_TRACE;
> + } else
> + tu->flags &= ~TP_FLAG_PROFILE;
> + }
This is correct, but again, this is not immediately obvious.
Why it is correct to correct to clear TP_FLAG_TRACE? Because we know
that "enabled" was false and thus we remove the single list entry.
So, perhaps,
if (enabled)
return 0;
ret = uprobe_register();
if (ret) {
...;
}
return ret;
will be a bit more clean.
Oleg.
On 07/01, Oleg Nesterov wrote:
>
> On 06/29, zhangwei(Jovi) wrote:
> >
> > [v3->v4]:
>
> I am wondering how much you will hate me if I suggest to make v5 ;)
>
> But look, imho probe_event_enable() looks a bit more confusing than
> it needs.
And I am a bit worried this patch removes the is_trace_uprobe_enabled()
check from probe_event_enable()...
Yes I think it was never needed, afaics TRACE_REG_*_UNREGISTER can't
come without successfull _REGISTER. And the bogus uprobe_unregister()
is harmless in this particular case.
So I think this is fine, but perhaps the changelog should mention this
"offtopic" change.
Oleg.
On 2013/7/2 4:27, Oleg Nesterov wrote:
> On 06/29, zhangwei(Jovi) wrote:
>>
>> [v3->v4]:
>
> I am wondering how much you will hate me if I suggest to make v5 ;)
>
Feel free to do that :)
> But look, imho probe_event_enable() looks a bit more confusing than
> it needs.
>
>> -probe_event_enable(struct trace_uprobe *tu, int flag, filter_func_t filter)
>> +probe_event_enable(struct trace_uprobe *tu, struct ftrace_event_file *file,
>> + filter_func_t filter)
>> {
>> + bool enabled = is_trace_uprobe_enabled(tu);
>> + struct event_file_link *link;
>> int ret = 0;
>
> Unnecessary initialization.
>
>> - if (is_trace_uprobe_enabled(tu))
>> - return -EINTR;
>> + if (file) {
>> + if (tu->flags & TP_FLAG_PROFILE)
>> + return -EINTR;
>> +
>> + link = kmalloc(sizeof(*link), GFP_KERNEL);
>> + if (!link)
>> + return -ENOMEM;
>> +
>> + link->file = file;
>> + list_add_tail_rcu(&link->list, &tu->files);
>> +
>> + tu->flags |= TP_FLAG_TRACE;
>> + } else {
>> + if (tu->flags & TP_FLAG_TRACE)
>> + return -EINTR;
>> +
>> + tu->flags |= TP_FLAG_PROFILE;
>> + }
>>
>> WARN_ON(!uprobe_filter_is_empty(&tu->filter));
>>
>> - tu->flags |= flag;
>> - tu->consumer.filter = filter;
>> - ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
>> - if (ret)
>> - tu->flags &= ~flag;
>> + /* we cannot call uprobe_register twice for same tu */
>
> The comment is confusing, I'd suggest to simply remove it.
>
> Yes, we can't do uprobe_register() twice as we already discussed.
> But it is not that we "can't", we simply do not need this if uprobe
> was already created.
>
>> + if (!enabled) {
>> + tu->consumer.filter = filter;
>> + ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
>> + }
>> +
>> + if (ret) {
>> + if (file) {
>> + list_del_rcu(&link->list);
>
> I won't insist, but _rcu is not needed in this case. Again, this looks
> a bit confusing, as if we expect that some rcu reader can ever see this
> entry. But this is not true and we are going to just kfree it without
> synchronize_rcu().
>
Yes, _rcu is not needed in there.
>> + kfree(link);
>> + tu->flags &= ~TP_FLAG_TRACE;
>> + } else
>> + tu->flags &= ~TP_FLAG_PROFILE;
>> + }
>
> This is correct, but again, this is not immediately obvious.
>
> Why it is correct to correct to clear TP_FLAG_TRACE? Because we know
> that "enabled" was false and thus we remove the single list entry.
>
> So, perhaps,
>
> if (enabled)
> return 0;
>
> ret = uprobe_register();
> if (ret) {
> ...;
> }
>
> return ret;
>
> will be a bit more clean.
>
I will change it in v5 patch.
> Oleg.
>
>
> .
>
On 2013/7/2 5:10, Oleg Nesterov wrote:
> On 07/01, Oleg Nesterov wrote:
>>
>> On 06/29, zhangwei(Jovi) wrote:
>>>
>>> [v3->v4]:
>>
>> I am wondering how much you will hate me if I suggest to make v5 ;)
>>
>> But look, imho probe_event_enable() looks a bit more confusing than
>> it needs.
>
> And I am a bit worried this patch removes the is_trace_uprobe_enabled()
> check from probe_event_enable()...
>
> Yes I think it was never needed, afaics TRACE_REG_*_UNREGISTER can't
> come without successfull _REGISTER. And the bogus uprobe_unregister()
> is harmless in this particular case.
>
> So I think this is fine, but perhaps the changelog should mention this
> "offtopic" change.
>
> Oleg.
>
I think it would be better to leave that checking in there now, we can remove
that checking in a separated patch if needed.
(I need to make sure the code will not go to there because each ftrace_event_file
already have enable/disable flag, also need to look at perf enable/disable case).
jovi
A comment I just have is a cosmetic one.
(2013/06/29 16:51), zhangwei(Jovi) wrote:
> @@ -605,33 +629,87 @@ typedef bool (*filter_func_t)(struct uprobe_consumer *self,
> struct mm_struct *mm);
>
> static int
> -probe_event_enable(struct trace_uprobe *tu, int flag, filter_func_t filter)
> +probe_event_enable(struct trace_uprobe *tu, struct ftrace_event_file *file,
> + filter_func_t filter)
> {
> + bool enabled = is_trace_uprobe_enabled(tu);
> + struct event_file_link *link;
> int ret = 0;
>
> - if (is_trace_uprobe_enabled(tu))
> - return -EINTR;
> + if (file) {
> + if (tu->flags & TP_FLAG_PROFILE)
> + return -EINTR;
> +
> + link = kmalloc(sizeof(*link), GFP_KERNEL);
> + if (!link)
> + return -ENOMEM;
> +
> + link->file = file;
> + list_add_tail_rcu(&link->list, &tu->files);
> +
> + tu->flags |= TP_FLAG_TRACE;
> + } else {
> + if (tu->flags & TP_FLAG_TRACE)
> + return -EINTR;
> +
> + tu->flags |= TP_FLAG_PROFILE;
> + }
>
> WARN_ON(!uprobe_filter_is_empty(&tu->filter));
>
> - tu->flags |= flag;
> - tu->consumer.filter = filter;
> - ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
> - if (ret)
> - tu->flags &= ~flag;
> + /* we cannot call uprobe_register twice for same tu */
> + if (!enabled) {
> + tu->consumer.filter = filter;
> + ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
> + }
> +
> + if (ret) {
Here, since the ret is only changed by uprobe_register, this block
would better be included in the above block. :)
> + if (file) {
> + list_del_rcu(&link->list);
> + kfree(link);
> + tu->flags &= ~TP_FLAG_TRACE;
> + } else
> + tu->flags &= ~TP_FLAG_PROFILE;
> + }
>
> return ret;
> }
Thank you,
--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: [email protected]