[PATCH] Added in user-injected messages into blk traces

[PATCH] Added in user-injected messages into blk traces

[Alan D. Brunelle]

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[-- Attachment #2: 0001-Added-in-user-injected-messages-into-blk-traces.patch --]
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This allows a user to annotate the blk trace stream: writing a suitable
message to {/sys/kernel/debug}/block/<dsf>/msg will have it propagated
into the trace stream.

Signed-off-by: Alan D. Brunelle <alan.brunelle@hp.com>
---
 block/blktrace.c             |   42 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/blktrace_api.h |    1 +
 2 files changed, 43 insertions(+), 0 deletions(-)

diff --git a/block/blktrace.c b/block/blktrace.c
index 38e6b83..b9c4df2 100644
--- a/block/blktrace.c
+++ b/block/blktrace.c
@@ -253,6 +253,7 @@ err:
 static void blk_trace_cleanup(struct blk_trace *bt)
 {
 	relay_close(bt->rchan);
+	debugfs_remove(bt->msg_file);
 	debugfs_remove(bt->dropped_file);
 	blk_remove_tree(bt->dir);
 	free_percpu(bt->sequence);
@@ -299,6 +300,41 @@ static const struct file_operations blk_dropped_fops = {
 	.read =		blk_dropped_read,
 };
 
+static int blk_msg_open(struct inode *inode, struct file *filp)
+{
+	filp->private_data = inode->i_private;
+
+	return 0;
+}
+
+static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
+				size_t count, loff_t *ppos)
+{
+	ssize_t ret = count;
+
+	if (count > BLK_TN_MAX_MSG)
+		ret = -EINVAL;
+	else {
+		char *msg = kmalloc(BLK_TN_MAX_MSG, GFP_KERNEL);
+
+		if (copy_from_user(msg, buffer, count))
+			ret = -EFAULT;
+		else {
+			struct blk_trace *bt = filp->private_data;
+			__trace_note_message(bt, "%s", msg);
+		}
+		kfree(msg);
+	}
+
+	return ret;
+}
+
+static const struct file_operations blk_msg_fops = {
+	.owner =	THIS_MODULE,
+	.open =		blk_msg_open,
+	.write =	blk_msg_write,
+};
+
 /*
  * Keep track of how many times we encountered a full subbuffer, to aid
  * the user space app in telling how many lost events there were.
@@ -384,6 +420,10 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 	if (!bt->dropped_file)
 		goto err;
 
+	bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
+	if (!bt->msg_file)
+		goto err;
+
 	bt->rchan = relay_open("trace", dir, buts->buf_size,
 				buts->buf_nr, &blk_relay_callbacks, bt);
 	if (!bt->rchan)
@@ -413,6 +453,8 @@ err:
 	if (dir)
 		blk_remove_tree(dir);
 	if (bt) {
+		if (bt->msg_file)
+			debugfs_remove(bt->msg_file);
 		if (bt->dropped_file)
 			debugfs_remove(bt->dropped_file);
 		free_percpu(bt->sequence);
diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h
index 3228caa..41208f1 100644
--- a/include/linux/blktrace_api.h
+++ b/include/linux/blktrace_api.h
@@ -128,6 +128,7 @@ struct blk_trace {
 	u32 dev;
 	struct dentry *dir;
 	struct dentry *dropped_file;
+	struct dentry *msg_file;
 	atomic_t dropped;
 };
 
-- 
1.5.4.3

Re: [PATCH] Added in user-injected messages into blk traces

[Jens Axboe]

On Thu, Jun 05 2008, Alan D. Brunelle wrote:

> This allows a user to annotate the blk trace stream: writing a suitable
> message to {/sys/kernel/debug}/block/<dsf>/msg will have it propagated
> into the trace stream.

Looks good to me, I think this can be useful for ease of trace
annotation. Comments below.

> Signed-off-by: Alan D. Brunelle <alan.brunelle@hp.com>
> ---
>  block/blktrace.c             |   42 ++++++++++++++++++++++++++++++++++++++++++
>  include/linux/blktrace_api.h |    1 +
>  2 files changed, 43 insertions(+), 0 deletions(-)
> 
> diff --git a/block/blktrace.c b/block/blktrace.c
> index 38e6b83..b9c4df2 100644
> --- a/block/blktrace.c
> +++ b/block/blktrace.c
> @@ -253,6 +253,7 @@ err:
>  static void blk_trace_cleanup(struct blk_trace *bt)
>  {
>  	relay_close(bt->rchan);
> +	debugfs_remove(bt->msg_file);
>  	debugfs_remove(bt->dropped_file);
>  	blk_remove_tree(bt->dir);
>  	free_percpu(bt->sequence);
> @@ -299,6 +300,41 @@ static const struct file_operations blk_dropped_fops = {
>  	.read =		blk_dropped_read,
>  };
>  
> +static int blk_msg_open(struct inode *inode, struct file *filp)
> +{
> +	filp->private_data = inode->i_private;
> +
> +	return 0;
> +}
> +
> +static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
> +				size_t count, loff_t *ppos)
> +{
> +	ssize_t ret = count;
> +
> +	if (count > BLK_TN_MAX_MSG)
> +		ret = -EINVAL;
> +	else {
> +		char *msg = kmalloc(BLK_TN_MAX_MSG, GFP_KERNEL);
> +
> +		if (copy_from_user(msg, buffer, count))
> +			ret = -EFAULT;
> +		else {
> +			struct blk_trace *bt = filp->private_data;
> +			__trace_note_message(bt, "%s", msg);
> +		}
> +		kfree(msg);

Would be cleaner with an explicit !msg check, though I think
copy_from_user() will notice and it'll work as-is.

if (count > BLK_TN_MAX_MSG)
        return -EINVAL;

msg = kmalloc(BLK_TN_MAX_MSG, GFP_KERNEL);
if (!msg)
        return -ENOMEM;

if (copy_from_user(msg, buffer, count))
        return -EFAULT;

...

is just a lot easier to directly follow imho. Otherwise I have no
problems with it, if you fix that up we can queue it for 2.6.27
inclusion.

-- 
Jens Axboe

Re: [PATCH] Added in user-injected messages into blk traces

[Alan D. Brunelle]

Jens Axboe wrote:
> On Thu, Jun 05 2008, Alan D. Brunelle wrote:
> 
>> This allows a user to annotate the blk trace stream: writing a suitable
>> message to {/sys/kernel/debug}/block/<dsf>/msg will have it propagated
>> into the trace stream.
> 
> Looks good to me, I think this can be useful for ease of trace
> annotation. Comments below.
> 
>> Signed-off-by: Alan D. Brunelle <alan.brunelle@hp.com>
>> ---
>>  block/blktrace.c             |   42 ++++++++++++++++++++++++++++++++++++++++++
>>  include/linux/blktrace_api.h |    1 +
>>  2 files changed, 43 insertions(+), 0 deletions(-)
>>
>> diff --git a/block/blktrace.c b/block/blktrace.c
>> index 38e6b83..b9c4df2 100644
>> --- a/block/blktrace.c
>> +++ b/block/blktrace.c
>> @@ -253,6 +253,7 @@ err:
>>  static void blk_trace_cleanup(struct blk_trace *bt)
>>  {
>>  	relay_close(bt->rchan);
>> +	debugfs_remove(bt->msg_file);
>>  	debugfs_remove(bt->dropped_file);
>>  	blk_remove_tree(bt->dir);
>>  	free_percpu(bt->sequence);
>> @@ -299,6 +300,41 @@ static const struct file_operations blk_dropped_fops = {
>>  	.read =		blk_dropped_read,
>>  };
>>  
>> +static int blk_msg_open(struct inode *inode, struct file *filp)
>> +{
>> +	filp->private_data = inode->i_private;
>> +
>> +	return 0;
>> +}
>> +
>> +static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
>> +				size_t count, loff_t *ppos)
>> +{
>> +	ssize_t ret = count;
>> +
>> +	if (count > BLK_TN_MAX_MSG)
>> +		ret = -EINVAL;
>> +	else {
>> +		char *msg = kmalloc(BLK_TN_MAX_MSG, GFP_KERNEL);
>> +
>> +		if (copy_from_user(msg, buffer, count))
>> +			ret = -EFAULT;
>> +		else {
>> +			struct blk_trace *bt = filp->private_data;
>> +			__trace_note_message(bt, "%s", msg);
>> +		}
>> +		kfree(msg);
> 
> Would be cleaner with an explicit !msg check, though I think
> copy_from_user() will notice and it'll work as-is.
> 
> if (count > BLK_TN_MAX_MSG)
>         return -EINVAL;
> 
> msg = kmalloc(BLK_TN_MAX_MSG, GFP_KERNEL);
> if (!msg)
>         return -ENOMEM;
> 
> if (copy_from_user(msg, buffer, count))
>         return -EFAULT;
> 
> ...
> 
> is just a lot easier to directly follow imho. Otherwise I have no
> problems with it, if you fix that up we can queue it for 2.6.27
> inclusion.
> 

Good points, will clean up and resubmit.

Thanks,
Alan

[PATCH] Added in user-injected messages into blk traces

[Alan D. Brunelle]

[-- Attachment #1: Type: text/plain, Size: 1 bytes --]



[-- Attachment #2: 0001-Added-in-user-injected-messages-into-blk-traces.patch --]
[-- Type: text/x-diff, Size: 2665 bytes --]


This allows a user to annotate the blk trace stream: writing a suitable
message to {/sys/kernel/debug}/block/<dsf>/msg will have it propagated
into the trace stream.

Signed-off-by: Alan D. Brunelle <alan.brunelle@hp.com>
---
 block/blktrace.c             |   45 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/blktrace_api.h |    1 +
 2 files changed, 46 insertions(+), 0 deletions(-)

diff --git a/block/blktrace.c b/block/blktrace.c
index 7ae87cc..63ed9cf 100644
--- a/block/blktrace.c
+++ b/block/blktrace.c
@@ -246,6 +246,7 @@ err:
 static void blk_trace_cleanup(struct blk_trace *bt)
 {
 	relay_close(bt->rchan);
+	debugfs_remove(bt->msg_file);
 	debugfs_remove(bt->dropped_file);
 	blk_remove_tree(bt->dir);
 	free_percpu(bt->sequence);
@@ -293,6 +294,44 @@ static const struct file_operations blk_dropped_fops = {
 	.read =		blk_dropped_read,
 };
 
+static int blk_msg_open(struct inode *inode, struct file *filp)
+{
+	filp->private_data = inode->i_private;
+
+	return 0;
+}
+
+static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
+				size_t count, loff_t *ppos)
+{
+	char *msg;
+	struct blk_trace *bt;
+
+	if (count > BLK_TN_MAX_MSG)
+		return -EINVAL;
+
+	msg = kmalloc(count, GFP_KERNEL);
+	if (msg == NULL)
+		return -ENOMEM;
+
+	if (copy_from_user(msg, buffer, count)) {
+		kfree(msg);
+		return -EFAULT;
+	}
+
+	bt = filp->private_data;
+	__trace_note_message(bt, "%s", msg);
+	kfree(msg);
+
+	return count;
+}
+
+static const struct file_operations blk_msg_fops = {
+	.owner =	THIS_MODULE,
+	.open =		blk_msg_open,
+	.write =	blk_msg_write,
+};
+
 /*
  * Keep track of how many times we encountered a full subbuffer, to aid
  * the user space app in telling how many lost events there were.
@@ -382,6 +421,10 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 	if (!bt->dropped_file)
 		goto err;
 
+	bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);
+	if (!bt->msg_file)
+		goto err;
+
 	bt->rchan = relay_open("trace", dir, buts->buf_size,
 				buts->buf_nr, &blk_relay_callbacks, bt);
 	if (!bt->rchan)
@@ -411,6 +454,8 @@ err:
 	if (dir)
 		blk_remove_tree(dir);
 	if (bt) {
+		if (bt->msg_file)
+			debugfs_remove(bt->msg_file);
 		if (bt->dropped_file)
 			debugfs_remove(bt->dropped_file);
 		free_percpu(bt->sequence);
diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h
index e3ef903..d084b8d 100644
--- a/include/linux/blktrace_api.h
+++ b/include/linux/blktrace_api.h
@@ -129,6 +129,7 @@ struct blk_trace {
 	u32 dev;
 	struct dentry *dir;
 	struct dentry *dropped_file;
+	struct dentry *msg_file;
 	atomic_t dropped;
 };
 
-- 
1.5.4.3