Re: [PATCH v2 6/6] tracing: Change remove_event_file_dir() to clear "d_subdirs"->i_private
On Tue, 2013-07-30 at 10:28 +0900, Masami Hiramatsu wrote: > (2013/07/29 23:21), Oleg Nesterov wrote: > > On 07/29, Masami Hiramatsu wrote: > >> > >> (2013/07/27 2:25), Oleg Nesterov wrote: > >>> Change remove_event_file_dir() to clear ->i_private for every > >>> file we are going to remove. > >> > >> Oleg, I think this should be done first. > >> > >> AFAICS, your former patches depend strongly on this change. > >> Without this, they don't work as you expected, and it may > >> prevent git-bisect. > > > > Why? > > > > v2 specially does this in the last change for bisecting/etc. > > > > 1-4 change f_op->read/write to check i_private != NULL but until > > this final patch i_private == NULL is not possible. > > Ah, OK. So 1-4 changes still remain refcount code, then > it is safe, just i_private != NULL are added. I misread. I just ran them all individually applied through my ftrace stress tests. All passed, thus they are as bisectible as I would like them to be. -- Steve -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v2 6/6] tracing: Change remove_event_file_dir() to clear "d_subdirs"->i_private
(2013/07/29 23:21), Oleg Nesterov wrote: > On 07/29, Masami Hiramatsu wrote: >> >> (2013/07/27 2:25), Oleg Nesterov wrote: >>> Change remove_event_file_dir() to clear ->i_private for every >>> file we are going to remove. >> >> Oleg, I think this should be done first. >> >> AFAICS, your former patches depend strongly on this change. >> Without this, they don't work as you expected, and it may >> prevent git-bisect. > > Why? > > v2 specially does this in the last change for bisecting/etc. > > 1-4 change f_op->read/write to check i_private != NULL but until > this final patch i_private == NULL is not possible. Ah, OK. So 1-4 changes still remain refcount code, then it is safe, just i_private != NULL are added. I misread. >> I see, including this patch also breaks current ftrace. > > Could you clarify? Yes, let me add reviewed-by tags ;) Thank you, -- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu...@hitachi.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v2 6/6] tracing: Change remove_event_file_dir() to clear "d_subdirs"->i_private
On 07/29, Masami Hiramatsu wrote: > > (2013/07/27 2:25), Oleg Nesterov wrote: > > Change remove_event_file_dir() to clear ->i_private for every > > file we are going to remove. > > Oleg, I think this should be done first. > > AFAICS, your former patches depend strongly on this change. > Without this, they don't work as you expected, and it may > prevent git-bisect. Why? v2 specially does this in the last change for bisecting/etc. 1-4 change f_op->read/write to check i_private != NULL but until this final patch i_private == NULL is not possible. > I see, including this patch also breaks current ftrace. Could you clarify? Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v2 6/6] tracing: Change remove_event_file_dir() to clear "d_subdirs"->i_private
(2013/07/27 2:25), Oleg Nesterov wrote:
> Change remove_event_file_dir() to clear ->i_private for every
> file we are going to remove.
Oleg, I think this should be done first.
AFAICS, your former patches depend strongly on this change.
Without this, they don't work as you expected, and it may
prevent git-bisect.
I see, including this patch also breaks current ftrace.
Thus, IMHO, it would better to make a separate patch which just
nullifies i_private with adding some NULL checks where accessing
i_private to avoid the breakages.
This looks a bit long way round, but it ensures bisecting.
Thank you,
> tracing_open_generic_file() and tracing_release_generic_file()
> can go away, ftrace_enable_fops and ftrace_event_filter_fops()
> use tracing_open_generic() but only to check tracing_disabled.
>
> This fixes all races with event_remove() or instance_delete().
> f_op->read/write/whatever can never use the freed file/call,
> all event/* files were changed to check and use ->i_private
> under event_mutex.
>
> Note: this doesn't not fix other problems, event_remove() can
> destroy the active ftrace_event_call, we need more changes but
> those changes are completely orthogonal.
>
> Signed-off-by: Oleg Nesterov
> ---
> kernel/trace/trace_events.c | 41 +
> 1 files changed, 9 insertions(+), 32 deletions(-)
>
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index 2a4f68a..1112fa0 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -428,42 +428,20 @@ static void *event_file_data(struct file *filp)
>
> static void remove_event_file_dir(struct ftrace_event_file *file)
> {
> + struct dentry *dir = file->dir;
> + struct dentry *child;
> +
> + /* ->i_mutex is not needed, nobody can create/remove a file */
> + list_for_each_entry(child, >d_subdirs, d_u.d_child)
> + child->d_inode->i_private = NULL;
> +
> list_del(>list);
> - debugfs_remove_recursive(file->dir);
> + debugfs_remove_recursive(dir);
> remove_subsystem(file->system);
> kmem_cache_free(file_cachep, file);
> }
>
> /*
> - * Open and update trace_array ref count.
> - * Must have the current trace_array passed to it.
> - */
> -static int tracing_open_generic_file(struct inode *inode, struct file *filp)
> -{
> - struct ftrace_event_file *file = inode->i_private;
> - struct trace_array *tr = file->tr;
> - int ret;
> -
> - if (trace_array_get(tr) < 0)
> - return -ENODEV;
> -
> - ret = tracing_open_generic(inode, filp);
> - if (ret < 0)
> - trace_array_put(tr);
> - return ret;
> -}
> -
> -static int tracing_release_generic_file(struct inode *inode, struct file
> *filp)
> -{
> - struct ftrace_event_file *file = inode->i_private;
> - struct trace_array *tr = file->tr;
> -
> - trace_array_put(tr);
> -
> - return 0;
> -}
> -
> -/*
> * __ftrace_set_clr_event(NULL, NULL, NULL, set) will set/unset all events.
> */
> static int
> @@ -1277,10 +1255,9 @@ static const struct file_operations
> ftrace_set_event_fops = {
> };
>
> static const struct file_operations ftrace_enable_fops = {
> - .open = tracing_open_generic_file,
> + .open = tracing_open_generic,
> .read = event_enable_read,
> .write = event_enable_write,
> - .release = tracing_release_generic_file,
> .llseek = default_llseek,
> };
>
>
--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu...@hitachi.com
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To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
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Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v2 6/6] tracing: Change remove_event_file_dir() to clear d_subdirs-i_private
(2013/07/27 2:25), Oleg Nesterov wrote:
Change remove_event_file_dir() to clear -i_private for every
file we are going to remove.
Oleg, I think this should be done first.
AFAICS, your former patches depend strongly on this change.
Without this, they don't work as you expected, and it may
prevent git-bisect.
I see, including this patch also breaks current ftrace.
Thus, IMHO, it would better to make a separate patch which just
nullifies i_private with adding some NULL checks where accessing
i_private to avoid the breakages.
This looks a bit long way round, but it ensures bisecting.
Thank you,
tracing_open_generic_file() and tracing_release_generic_file()
can go away, ftrace_enable_fops and ftrace_event_filter_fops()
use tracing_open_generic() but only to check tracing_disabled.
This fixes all races with event_remove() or instance_delete().
f_op-read/write/whatever can never use the freed file/call,
all event/* files were changed to check and use -i_private
under event_mutex.
Note: this doesn't not fix other problems, event_remove() can
destroy the active ftrace_event_call, we need more changes but
those changes are completely orthogonal.
Signed-off-by: Oleg Nesterov o...@redhat.com
---
kernel/trace/trace_events.c | 41 +
1 files changed, 9 insertions(+), 32 deletions(-)
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 2a4f68a..1112fa0 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -428,42 +428,20 @@ static void *event_file_data(struct file *filp)
static void remove_event_file_dir(struct ftrace_event_file *file)
{
+ struct dentry *dir = file-dir;
+ struct dentry *child;
+
+ /* -i_mutex is not needed, nobody can create/remove a file */
+ list_for_each_entry(child, dir-d_subdirs, d_u.d_child)
+ child-d_inode-i_private = NULL;
+
list_del(file-list);
- debugfs_remove_recursive(file-dir);
+ debugfs_remove_recursive(dir);
remove_subsystem(file-system);
kmem_cache_free(file_cachep, file);
}
/*
- * Open and update trace_array ref count.
- * Must have the current trace_array passed to it.
- */
-static int tracing_open_generic_file(struct inode *inode, struct file *filp)
-{
- struct ftrace_event_file *file = inode-i_private;
- struct trace_array *tr = file-tr;
- int ret;
-
- if (trace_array_get(tr) 0)
- return -ENODEV;
-
- ret = tracing_open_generic(inode, filp);
- if (ret 0)
- trace_array_put(tr);
- return ret;
-}
-
-static int tracing_release_generic_file(struct inode *inode, struct file
*filp)
-{
- struct ftrace_event_file *file = inode-i_private;
- struct trace_array *tr = file-tr;
-
- trace_array_put(tr);
-
- return 0;
-}
-
-/*
* __ftrace_set_clr_event(NULL, NULL, NULL, set) will set/unset all events.
*/
static int
@@ -1277,10 +1255,9 @@ static const struct file_operations
ftrace_set_event_fops = {
};
static const struct file_operations ftrace_enable_fops = {
- .open = tracing_open_generic_file,
+ .open = tracing_open_generic,
.read = event_enable_read,
.write = event_enable_write,
- .release = tracing_release_generic_file,
.llseek = default_llseek,
};
--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu...@hitachi.com
--
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v2 6/6] tracing: Change remove_event_file_dir() to clear d_subdirs-i_private
On 07/29, Masami Hiramatsu wrote: (2013/07/27 2:25), Oleg Nesterov wrote: Change remove_event_file_dir() to clear -i_private for every file we are going to remove. Oleg, I think this should be done first. AFAICS, your former patches depend strongly on this change. Without this, they don't work as you expected, and it may prevent git-bisect. Why? v2 specially does this in the last change for bisecting/etc. 1-4 change f_op-read/write to check i_private != NULL but until this final patch i_private == NULL is not possible. I see, including this patch also breaks current ftrace. Could you clarify? Oleg. -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v2 6/6] tracing: Change remove_event_file_dir() to clear d_subdirs-i_private
(2013/07/29 23:21), Oleg Nesterov wrote: On 07/29, Masami Hiramatsu wrote: (2013/07/27 2:25), Oleg Nesterov wrote: Change remove_event_file_dir() to clear -i_private for every file we are going to remove. Oleg, I think this should be done first. AFAICS, your former patches depend strongly on this change. Without this, they don't work as you expected, and it may prevent git-bisect. Why? v2 specially does this in the last change for bisecting/etc. 1-4 change f_op-read/write to check i_private != NULL but until this final patch i_private == NULL is not possible. Ah, OK. So 1-4 changes still remain refcount code, then it is safe, just i_private != NULL are added. I misread. I see, including this patch also breaks current ftrace. Could you clarify? Yes, let me add reviewed-by tags ;) Thank you, -- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu...@hitachi.com -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v2 6/6] tracing: Change remove_event_file_dir() to clear d_subdirs-i_private
On Tue, 2013-07-30 at 10:28 +0900, Masami Hiramatsu wrote: (2013/07/29 23:21), Oleg Nesterov wrote: On 07/29, Masami Hiramatsu wrote: (2013/07/27 2:25), Oleg Nesterov wrote: Change remove_event_file_dir() to clear -i_private for every file we are going to remove. Oleg, I think this should be done first. AFAICS, your former patches depend strongly on this change. Without this, they don't work as you expected, and it may prevent git-bisect. Why? v2 specially does this in the last change for bisecting/etc. 1-4 change f_op-read/write to check i_private != NULL but until this final patch i_private == NULL is not possible. Ah, OK. So 1-4 changes still remain refcount code, then it is safe, just i_private != NULL are added. I misread. I just ran them all individually applied through my ftrace stress tests. All passed, thus they are as bisectible as I would like them to be. -- Steve -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH v2 6/6] tracing: Change remove_event_file_dir() to clear "d_subdirs"->i_private
Change remove_event_file_dir() to clear ->i_private for every
file we are going to remove.
tracing_open_generic_file() and tracing_release_generic_file()
can go away, ftrace_enable_fops and ftrace_event_filter_fops()
use tracing_open_generic() but only to check tracing_disabled.
This fixes all races with event_remove() or instance_delete().
f_op->read/write/whatever can never use the freed file/call,
all event/* files were changed to check and use ->i_private
under event_mutex.
Note: this doesn't not fix other problems, event_remove() can
destroy the active ftrace_event_call, we need more changes but
those changes are completely orthogonal.
Signed-off-by: Oleg Nesterov
---
kernel/trace/trace_events.c | 41 +
1 files changed, 9 insertions(+), 32 deletions(-)
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 2a4f68a..1112fa0 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -428,42 +428,20 @@ static void *event_file_data(struct file *filp)
static void remove_event_file_dir(struct ftrace_event_file *file)
{
+ struct dentry *dir = file->dir;
+ struct dentry *child;
+
+ /* ->i_mutex is not needed, nobody can create/remove a file */
+ list_for_each_entry(child, >d_subdirs, d_u.d_child)
+ child->d_inode->i_private = NULL;
+
list_del(>list);
- debugfs_remove_recursive(file->dir);
+ debugfs_remove_recursive(dir);
remove_subsystem(file->system);
kmem_cache_free(file_cachep, file);
}
/*
- * Open and update trace_array ref count.
- * Must have the current trace_array passed to it.
- */
-static int tracing_open_generic_file(struct inode *inode, struct file *filp)
-{
- struct ftrace_event_file *file = inode->i_private;
- struct trace_array *tr = file->tr;
- int ret;
-
- if (trace_array_get(tr) < 0)
- return -ENODEV;
-
- ret = tracing_open_generic(inode, filp);
- if (ret < 0)
- trace_array_put(tr);
- return ret;
-}
-
-static int tracing_release_generic_file(struct inode *inode, struct file *filp)
-{
- struct ftrace_event_file *file = inode->i_private;
- struct trace_array *tr = file->tr;
-
- trace_array_put(tr);
-
- return 0;
-}
-
-/*
* __ftrace_set_clr_event(NULL, NULL, NULL, set) will set/unset all events.
*/
static int
@@ -1277,10 +1255,9 @@ static const struct file_operations
ftrace_set_event_fops = {
};
static const struct file_operations ftrace_enable_fops = {
- .open = tracing_open_generic_file,
+ .open = tracing_open_generic,
.read = event_enable_read,
.write = event_enable_write,
- .release = tracing_release_generic_file,
.llseek = default_llseek,
};
--
1.5.5.1
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[PATCH v2 6/6] tracing: Change remove_event_file_dir() to clear d_subdirs-i_private
Change remove_event_file_dir() to clear -i_private for every
file we are going to remove.
tracing_open_generic_file() and tracing_release_generic_file()
can go away, ftrace_enable_fops and ftrace_event_filter_fops()
use tracing_open_generic() but only to check tracing_disabled.
This fixes all races with event_remove() or instance_delete().
f_op-read/write/whatever can never use the freed file/call,
all event/* files were changed to check and use -i_private
under event_mutex.
Note: this doesn't not fix other problems, event_remove() can
destroy the active ftrace_event_call, we need more changes but
those changes are completely orthogonal.
Signed-off-by: Oleg Nesterov o...@redhat.com
---
kernel/trace/trace_events.c | 41 +
1 files changed, 9 insertions(+), 32 deletions(-)
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 2a4f68a..1112fa0 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -428,42 +428,20 @@ static void *event_file_data(struct file *filp)
static void remove_event_file_dir(struct ftrace_event_file *file)
{
+ struct dentry *dir = file-dir;
+ struct dentry *child;
+
+ /* -i_mutex is not needed, nobody can create/remove a file */
+ list_for_each_entry(child, dir-d_subdirs, d_u.d_child)
+ child-d_inode-i_private = NULL;
+
list_del(file-list);
- debugfs_remove_recursive(file-dir);
+ debugfs_remove_recursive(dir);
remove_subsystem(file-system);
kmem_cache_free(file_cachep, file);
}
/*
- * Open and update trace_array ref count.
- * Must have the current trace_array passed to it.
- */
-static int tracing_open_generic_file(struct inode *inode, struct file *filp)
-{
- struct ftrace_event_file *file = inode-i_private;
- struct trace_array *tr = file-tr;
- int ret;
-
- if (trace_array_get(tr) 0)
- return -ENODEV;
-
- ret = tracing_open_generic(inode, filp);
- if (ret 0)
- trace_array_put(tr);
- return ret;
-}
-
-static int tracing_release_generic_file(struct inode *inode, struct file *filp)
-{
- struct ftrace_event_file *file = inode-i_private;
- struct trace_array *tr = file-tr;
-
- trace_array_put(tr);
-
- return 0;
-}
-
-/*
* __ftrace_set_clr_event(NULL, NULL, NULL, set) will set/unset all events.
*/
static int
@@ -1277,10 +1255,9 @@ static const struct file_operations
ftrace_set_event_fops = {
};
static const struct file_operations ftrace_enable_fops = {
- .open = tracing_open_generic_file,
+ .open = tracing_open_generic,
.read = event_enable_read,
.write = event_enable_write,
- .release = tracing_release_generic_file,
.llseek = default_llseek,
};
--
1.5.5.1
--
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
