Re: [PATCH] mmc_test: move files from sysfs to debugfs

[Adrian Hunter <adrian.hunter@nokia.com>]

Andy Shevchenko wrote:
> As proposed by Greg the more logically is to keep files for mmc_test driver
> under debugfs.

What happens if debugfs is not enabled in config?  Should there be
some kind of dependency there?  At least an error message would be
good - see below.

> 
> Additionally this patch brings seq_file API for show() method. It allows to
> write unlimited data to the file.
> 
> Example of usage:
>   # mount -t debugfs none /sys/kernel/debug
>   # modprobe mmc_test
>     [  581.395843] mmc_test mmc0:0001: Card claimed for testing.
>   # echo 25 > /sys/kernel/debug/mmc0/mmc0\:0001/test
>     [  604.568542] mmc0: Starting tests of card mmc0:0001...
>     [  604.582733] mmc0: Test case 25. Best-case read performance into scattered pages...
>     [  604.923553] mmc0: Transfer of 8192 sectors (4096 KiB) took 0.124664314 seconds (33644 kB/s, 32856 KiB/s)
>     [  604.933227] mmc0: Result: OK
>     [  604.936248] mmc0: Tests completed.
>   # cat /sys/kernel/debug/mmc0/mmc0\:0001/test
>     Test 25: 0
>     1 8192 0.124664314 33644784
> 
> Signed-off-by: Andy Shevchenko <ext-andriy.shevchenko@nokia.com>
> ---
>  drivers/mmc/card/mmc_test.c |  138 ++++++++++++++++++++++++++++++++-----------
>  1 files changed, 103 insertions(+), 35 deletions(-)
> 
> diff --git a/drivers/mmc/card/mmc_test.c b/drivers/mmc/card/mmc_test.c
> index 58d746b..e59bb02 100644
> --- a/drivers/mmc/card/mmc_test.c
> +++ b/drivers/mmc/card/mmc_test.c
> @@ -19,6 +19,10 @@
>  #include <linux/swap.h>		/* For nr_free_buffer_pages() */
>  #include <linux/list.h>
>  
> +#include <linux/debugfs.h>
> +#include <asm/uaccess.h>
> +#include <linux/seq_file.h>
> +
>  #define RESULT_OK		0
>  #define RESULT_FAIL		1
>  #define RESULT_UNSUP_HOST	2
> @@ -106,6 +110,18 @@ struct mmc_test_general_result {
>  };
>  
>  /**
> + * struct mmc_test_dbgfs_file - debugfs related file.
> + * @link: double-linked list
> + * @card: card under test
> + * @file: file created under debugfs
> + */
> +struct mmc_test_dbgfs_file {
> +	struct list_head link;
> +	struct mmc_card *card;
> +	struct dentry *file;
> +};
> +
> +/**
>   * struct mmc_test_card - test information.
>   * @card: card under test
>   * @scratch: transfer buffer
> @@ -2037,14 +2053,12 @@ static void mmc_test_free_result(struct mmc_card *card)
>  	mutex_unlock(&mmc_test_lock);
>  }
>  
> -static ssize_t mmc_test_show(struct device *dev,
> -	struct device_attribute *attr, char *buf)
> +static LIST_HEAD(mmc_test_file_test);
> +
> +static int mtf_test_show(struct seq_file *sf, void *data)
>  {
> -	struct mmc_card *card = mmc_dev_to_card(dev);
> +	struct mmc_card *card = (struct mmc_card *)sf->private;
>  	struct mmc_test_general_result *gr;
> -	char *p = buf;
> -	size_t len = PAGE_SIZE;
> -	int ret;
>  
>  	mutex_lock(&mmc_test_lock);
>  
> @@ -2054,49 +2068,44 @@ static ssize_t mmc_test_show(struct device *dev,
>  		if (gr->card != card)
>  			continue;
>  
> -		ret = snprintf(p, len, "Test %d: %d\n", gr->testcase + 1,
> -			gr->result);
> -		if (ret < 0)
> -			goto err;
> -		if (ret >= len) {
> -			ret = -ENOBUFS;
> -			goto err;
> -		}
> -		p += ret;
> -		len -= ret;
> +		seq_printf(sf, "Test %d: %d\n", gr->testcase + 1, gr->result);
>  
>  		list_for_each_entry(tr, &gr->tr_lst, link) {
> -			ret = snprintf(p, len, "%u %d %lu.%09lu %u\n",
> +			seq_printf(sf, "%u %d %lu.%09lu %u\n",
>  				tr->count, tr->sectors,
>  				(unsigned long)tr->ts.tv_sec,
>  				(unsigned long)tr->ts.tv_nsec,
>  				tr->rate);
> -			if (ret < 0)
> -				goto err;
> -			if (ret >= len) {
> -				ret = -ENOBUFS;
> -				goto err;
> -			}
> -			p += ret;
> -			len -= ret;
>  		}
>  	}
>  
> -	ret = PAGE_SIZE - len;
> -err:
>  	mutex_unlock(&mmc_test_lock);
>  
> -	return ret;
> +	return 0;
>  }
>  
> -static ssize_t mmc_test_store(struct device *dev,
> -	struct device_attribute *attr, const char *buf, size_t count)
> +static int mtf_test_open(struct inode *inode, struct file *file)
>  {
> -	struct mmc_card *card = mmc_dev_to_card(dev);
> +	return single_open(file, mtf_test_show, inode->i_private);
> +}
> +
> +static ssize_t mtf_test_write(struct file *file, const char __user *buf,
> +	size_t count, loff_t *pos)
> +{
> +	struct seq_file *sf = (struct seq_file *)file->private_data;
> +	struct mmc_card *card = (struct mmc_card *)sf->private;
>  	struct mmc_test_card *test;
> +	char lbuf[12];
>  	long testcase;
>  
> -	if (strict_strtol(buf, 10, &testcase))
> +	if (count >= sizeof(lbuf))
> +		return -EINVAL;
> +
> +	if (copy_from_user(lbuf, buf, count))
> +		return -EFAULT;
> +	lbuf[count] = '\0';
> +
> +	if (strict_strtol(lbuf, 10, &testcase))
>  		return -EINVAL;
>  
>  	test = kzalloc(sizeof(struct mmc_test_card), GFP_KERNEL);
> @@ -2135,7 +2144,65 @@ static ssize_t mmc_test_store(struct device *dev,
>  	return count;
>  }
>  
> -static DEVICE_ATTR(test, S_IWUSR | S_IRUGO, mmc_test_show, mmc_test_store);
> +static const struct file_operations mmc_test_fops_test = {
> +	.open		= mtf_test_open,
> +	.read		= seq_read,
> +	.write		= mtf_test_write,
> +	.llseek		= seq_lseek,
> +	.release	= single_release,
> +};
> +
> +static void mmc_test_free_file_test(struct mmc_card *card)
> +{
> +	struct mmc_test_dbgfs_file *df, *dfs;
> +
> +	mutex_lock(&mmc_test_lock);
> +
> +	list_for_each_entry_safe(df, dfs, &mmc_test_file_test, link) {
> +		if (card && df->card != card)
> +			continue;
> +		debugfs_remove(df->file);
> +		list_del(&df->link);
> +		kfree(df);
> +	}
> +
> +	mutex_unlock(&mmc_test_lock);
> +}
> +
> +static int mmc_test_register_file_test(struct mmc_card *card)
> +{
> +	struct dentry *file = NULL;
> +	struct mmc_test_dbgfs_file *df;
> +	int ret = 0;
> +
> +	mutex_lock(&mmc_test_lock);
> +
> +	if (card->debugfs_root)
> +		file = debugfs_create_file("test", S_IWUSR, card->debugfs_root,
> +			card, &mmc_test_fops_test);
> +
> +	if (IS_ERR_OR_NULL(file)) {

Perhaps a error message should be printed here.

> +		ret = -ENODEV;
> +		goto err;
> +	}
> +
> +	df = kmalloc(sizeof(struct mmc_test_dbgfs_file), GFP_KERNEL);
> +	if (!df) {
> +		debugfs_remove(file);
> +		ret = -ENOMEM;
> +		goto err;
> +	}
> +
> +	df->card = card;
> +	df->file = file;
> +
> +	list_add(&df->link, &mmc_test_file_test);
> +
> +err:
> +	mutex_unlock(&mmc_test_lock);
> +
> +	return ret;
> +}
>  
>  static int mmc_test_probe(struct mmc_card *card)
>  {
> @@ -2144,7 +2211,7 @@ static int mmc_test_probe(struct mmc_card *card)
>  	if (!mmc_card_mmc(card) && !mmc_card_sd(card))
>  		return -ENODEV;
>  
> -	ret = device_create_file(&card->dev, &dev_attr_test);
> +	ret = mmc_test_register_file_test(card);
>  	if (ret)
>  		return ret;
>  
> @@ -2156,7 +2223,7 @@ static int mmc_test_probe(struct mmc_card *card)
>  static void mmc_test_remove(struct mmc_card *card)
>  {
>  	mmc_test_free_result(card);
> -	device_remove_file(&card->dev, &dev_attr_test);
> +	mmc_test_free_file_test(card);
>  }
>  
>  static struct mmc_driver mmc_driver = {
> @@ -2176,6 +2243,7 @@ static void __exit mmc_test_exit(void)
>  {
>  	/* Clear stalled data if card is still plugged */
>  	mmc_test_free_result(NULL);
> +	mmc_test_free_file_test(NULL);
>  
>  	mmc_unregister_driver(&mmc_driver);
>  }