[PATCH] comedi: comedi_bond: Refactor strlcat() to seq_buf in do_dev_config()

[PATCH] comedi: comedi_bond: Refactor strlcat() to seq_buf in do_dev_config()

[Mariia Nikitash]

From: Bill Wendling <morbo@google.com>

do_dev_config() builds a space-separated list of bonded devices in
devpriv->name by formatting each "minor:subdev " pair into a temporary
stack buffer with snprintf() and appending it with strlcat() in a loop.

In preparation for removing the deprecated strlcat() API[1], use struct
seq_buf and seq_buf_printf() to format each entry directly into
devpriv->name. This avoids repeated rescanning of devpriv->name and
eliminates the temporary buffer.

Link: https://github.com/KSPP/linux/issues/370 [1]
Cc: codemender-patching+linux@google.com
Assisted-by: LLM
Signed-off-by: Bill Wendling <morbo@google.com>
Signed-off-by: Mariia Nikitash <nikitash.mariiaw@gmail.com>
---
 drivers/comedi/drivers/comedi_bond.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/drivers/comedi/drivers/comedi_bond.c b/drivers/comedi/drivers/comedi_bond.c
index 8e10ecab4f0d..a10cfbd04c72 100644
--- a/drivers/comedi/drivers/comedi_bond.c
+++ b/drivers/comedi/drivers/comedi_bond.c
@@ -39,6 +39,7 @@
 
 #include <linux/module.h>
 #include <linux/string.h>
+#include <linux/seq_buf.h>
 #include <linux/slab.h>
 #include <linux/comedi.h>
 #include <linux/comedi/comedilib.h>
@@ -170,10 +171,11 @@ static int do_dev_config(struct comedi_device *dev, struct comedi_devconfig *it)
 {
 	struct comedi_bond_private *devpriv = dev->private;
 	DECLARE_BITMAP(devs_opened, COMEDI_NUM_BOARD_MINORS);
+	struct seq_buf s;
 	int i;
 
 	memset(&devs_opened, 0, sizeof(devs_opened));
-	devpriv->name[0] = 0;
+	seq_buf_init(&s, devpriv->name, sizeof(devpriv->name));
 	/*
 	 * Loop through all comedi devices specified on the command-line,
 	 * building our device list.
@@ -250,15 +252,9 @@ static int do_dev_config(struct comedi_device *dev, struct comedi_devconfig *it)
 			}
 			devpriv->devs = devs;
 			devpriv->devs[devpriv->ndevs++] = bdev;
-			{
-				/* Append dev:subdev to devpriv->name */
-				char buf[20];
-
-				snprintf(buf, sizeof(buf), "%u:%u ",
-					 bdev->minor, bdev->subdev);
-				strlcat(devpriv->name, buf,
-					sizeof(devpriv->name));
-			}
+
+			/* Append dev:subdev to devpriv->name */
+			seq_buf_printf(&s, "%u:%u ", bdev->minor, bdev->subdev);
 		}
 	}
 
@@ -267,6 +263,8 @@ static int do_dev_config(struct comedi_device *dev, struct comedi_devconfig *it)
 		return -EINVAL;
 	}
 
+	seq_buf_str(&s);
+
 	return 0;
 }
 
-- 
2.43.0

Re: [PATCH] comedi: comedi_bond: Refactor strlcat() to seq_buf in do_dev_config()

[Ian Abbott]

On 27/09/2026 07:00, Mariia Nikitash wrote:
> From: Bill Wendling <morbo@google.com>
> 
> do_dev_config() builds a space-separated list of bonded devices in
> devpriv->name by formatting each "minor:subdev " pair into a temporary
> stack buffer with snprintf() and appending it with strlcat() in a loop.
> 
> In preparation for removing the deprecated strlcat() API[1], use struct
> seq_buf and seq_buf_printf() to format each entry directly into
> devpriv->name. This avoids repeated rescanning of devpriv->name and
> eliminates the temporary buffer.
> 
> Link: https://github.com/KSPP/linux/issues/370 [1]
> Cc: codemender-patching+linux@google.com
> Assisted-by: LLM
> Signed-off-by: Bill Wendling <morbo@google.com>
> Signed-off-by: Mariia Nikitash <nikitash.mariiaw@gmail.com>
> ---
>   drivers/comedi/drivers/comedi_bond.c | 18 ++++++++----------
>   1 file changed, 8 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/comedi/drivers/comedi_bond.c b/drivers/comedi/drivers/comedi_bond.c
> index 8e10ecab4f0d..a10cfbd04c72 100644
> --- a/drivers/comedi/drivers/comedi_bond.c
> +++ b/drivers/comedi/drivers/comedi_bond.c
> @@ -39,6 +39,7 @@
>   
>   #include <linux/module.h>
>   #include <linux/string.h>
> +#include <linux/seq_buf.h>
>   #include <linux/slab.h>
>   #include <linux/comedi.h>
>   #include <linux/comedi/comedilib.h>
> @@ -170,10 +171,11 @@ static int do_dev_config(struct comedi_device *dev, struct comedi_devconfig *it)
>   {
>   	struct comedi_bond_private *devpriv = dev->private;
>   	DECLARE_BITMAP(devs_opened, COMEDI_NUM_BOARD_MINORS);
> +	struct seq_buf s;
>   	int i;
>   
>   	memset(&devs_opened, 0, sizeof(devs_opened));
> -	devpriv->name[0] = 0;
> +	seq_buf_init(&s, devpriv->name, sizeof(devpriv->name));
>   	/*
>   	 * Loop through all comedi devices specified on the command-line,
>   	 * building our device list.
> @@ -250,15 +252,9 @@ static int do_dev_config(struct comedi_device *dev, struct comedi_devconfig *it)
>   			}
>   			devpriv->devs = devs;
>   			devpriv->devs[devpriv->ndevs++] = bdev;
> -			{
> -				/* Append dev:subdev to devpriv->name */
> -				char buf[20];
> -
> -				snprintf(buf, sizeof(buf), "%u:%u ",
> -					 bdev->minor, bdev->subdev);
> -				strlcat(devpriv->name, buf,
> -					sizeof(devpriv->name));
> -			}
> +
> +			/* Append dev:subdev to devpriv->name */
> +			seq_buf_printf(&s, "%u:%u ", bdev->minor, bdev->subdev);
>   		}
>   	}
>   
> @@ -267,6 +263,8 @@ static int do_dev_config(struct comedi_device *dev, struct comedi_devconfig *it)
>   		return -EINVAL;
>   	}
>   
> +	seq_buf_str(&s);
> +
>   	return 0;
>   }
>   

Looks good, thanks!

Reviewed-by: Ian Abbott <abbotti@mev.co.uk>

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