linux-kernel - Re: [PATCH 07/18] dma-debug: add debugfs interface

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Date:	Fri, 6 Mar 2009 14:45:28 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Joerg Roedel <joerg.roedel@....com>
Cc:	mingo@...hat.com, linux-kernel@...r.kernel.org,
	iommu@...ts.linux-foundation.org
Subject: Re: [PATCH 07/18] dma-debug: add debugfs interface

On Fri, Mar 06, 2009 at 02:30:18PM +0100, Joerg Roedel wrote:
> Impact: add debugfs interface for configuring DMA-API debugging
> 
> Signed-off-by: Joerg Roedel <joerg.roedel@....com>
> ---
>  lib/dma-debug.c |   78 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 78 insertions(+), 0 deletions(-)
> 
> diff --git a/lib/dma-debug.c b/lib/dma-debug.c
> index 2ede463..20d6cdb 100644
> --- a/lib/dma-debug.c
> +++ b/lib/dma-debug.c
> @@ -19,6 +19,7 @@
>  
>  #include <linux/dma-debug.h>
>  #include <linux/spinlock.h>
> +#include <linux/debugfs.h>
>  #include <linux/types.h>
>  #include <linux/list.h>
>  #include <linux/slab.h>
> @@ -61,12 +62,29 @@ static DEFINE_SPINLOCK(free_entries_lock);
>  /* Global disable flag - will be set in case of an error */
>  static bool global_disable __read_mostly;
>  
> +/* Global error count */
> +static u32 error_count;
> +
> +/* Global error show enable*/
> +static u32 show_all_errors __read_mostly;
> +/* Number of errors to show */
> +static u32 show_num_errors = 1;
> +
>  static u32 num_free_entries;
>  static u32 min_free_entries;
>  
>  /* number of preallocated entries requested by kernel cmdline */
>  static u32 req_entries;
>  
> +/* debugfs dentry's for the stuff above */
> +static struct dentry *dma_debug_dent        __read_mostly;
> +static struct dentry *global_disable_dent   __read_mostly;
> +static struct dentry *error_count_dent      __read_mostly;
> +static struct dentry *show_all_errors_dent  __read_mostly;
> +static struct dentry *show_num_errors_dent  __read_mostly;
> +static struct dentry *num_free_entries_dent __read_mostly;
> +static struct dentry *min_free_entries_dent __read_mostly;
> +
>  /*
>   * Hash related functions
>   *
> @@ -241,6 +259,58 @@ out_err:
>  	return -ENOMEM;
>  }
>  
> +static int dma_debug_fs_init(void)
> +{
> +	dma_debug_dent = debugfs_create_dir("dma-api", NULL);
> +	if (!dma_debug_dent) {
> +		printk(KERN_ERR "DMA-API: can not create debugfs directory\n");
> +		return -ENOMEM;
> +	}
> +
> +	global_disable_dent = debugfs_create_bool("disabled", 0444,
> +			dma_debug_dent,
> +			(u32 *)&global_disable);
> +	if (!global_disable_dent)
> +		goto out_err;
> +
> +	error_count_dent = debugfs_create_u32("error_count", 0444,
> +			dma_debug_dent, &error_count);
> +	if (!error_count_dent)
> +		goto out_err;
> +
> +	show_all_errors_dent = debugfs_create_u32("all_errors", 0644,
> +			dma_debug_dent,
> +			&show_all_errors);
> +	if (!show_all_errors_dent)
> +		goto out_err;
> +
> +	show_num_errors_dent = debugfs_create_u32("num_errors", 0644,
> +			dma_debug_dent,
> +			&show_num_errors);
> +	if (!show_num_errors_dent)
> +		goto out_err;
> +
> +	num_free_entries_dent = debugfs_create_u32("num_free_entries", 0444,
> +			dma_debug_dent,
> +			&num_free_entries);
> +	if (!num_free_entries_dent)
> +		goto out_err;
> +
> +	min_free_entries_dent = debugfs_create_u32("min_free_entries", 0444,
> +			dma_debug_dent,
> +			&min_free_entries);
> +	if (!min_free_entries_dent)
> +		goto out_err;


Hi,

At least for the read-only files, why not create a single file
which displays num_free_entries, min_free_entries and global disable?


> +
> +	return 0;
> +
> +out_err:
> +	debugfs_remove_recursive(dma_debug_dent);
> +
> +	return -ENOMEM;
> +}
> +
> +
>  /*
>   * Let the architectures decide how many entries should be preallocated.
>   */
> @@ -256,6 +326,14 @@ void dma_debug_init(u32 num_entries)
>  		dma_entry_hash[i].lock = SPIN_LOCK_UNLOCKED;
>  	}
>  
> +	if (dma_debug_fs_init() != 0) {
> +		printk(KERN_ERR "DMA-API: error creating debugfs entries "
> +				"- disabling\n");
> +		global_disable = true;
> +
> +		return;
> +	}
> +
>  	if (req_entries)
>  		num_entries = req_entries;
>  
> -- 
> 1.5.6.4
> 
> 
> --
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