Re: [PATCH v3] phram: Allow the user to set the erase page size.

[Miquel Raynal <miquel.raynal@bootlin.com>]

Hi Guohua,

Guohua Zhong <zhongguohua1@huawei.com> wrote on Mon, 7 Dec 2020
16:53:42 +0800:

> From: Patrick O'Grady <patrick@baymotion.com>
> 
> Permit the user to specify the erase page size as a parameter.
> This solves two problems:
> 
> - phram can access images made by mkfs.jffs2.  mkfs.jffs2 won't
> create images with erase sizes less than 8KiB; many architectures
> define PAGE_SIZE as 4KiB.
> 
> - Allows more effective use of small capacity devices.  JFFS2
> needs somewhere between 2 and 5 empty pages for garbage collection;
> and for an NVRAM part with only 32KiB of space, a smaller erase page
> allows much better utilization in applications where garbage collection
> is important.
> 
> Signed-off-by: Patrick O'Grady <patrick@baymotion.com>
> Reviewed-by: Joern Engel <joern@logfs.org>
> Link: https://lore.kernel.org/lkml/CAJ7m5OqYv_=JB9NhHsqBsa8YU0DFRoP7C+W10PY22wonAGJK=A@mail.gmail.com/
> [Guohua Zhong: fix token array index out of bounds and update patch for kernel master branch]
> Signed-off-by: Guohua Zhong <zhongguohua1@huawei.com>
> 
> v3:
>  update authorship for Patrick O'Grady and remove the reported-by tag for kernel test robot
> 
> v2: https://lore.kernel.org/lkml/20201204080821.46868-1-zhongguohua1@huawei.com/
>  fix build error which is reported by kernel test robot
> 
> v1: https://lore.kernel.org/lkml/20201124061053.10812-1-zhongguohua1@huawei.com/
>  1.fix token array index out of bounds
>  2.update patch for kernel master branch

I cannot apply your patch as-is: the changelog (v1, v2, etc) should be
below the three dashes...

> ---

...here!

Otherwise it would be part of the final commit message, which is not
something we want.

>  drivers/mtd/devices/phram.c | 52 +++++++++++++++++++++++++++++----------------
>  1 file changed, 34 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/mtd/devices/phram.c b/drivers/mtd/devices/phram.c
> index 087b5e86d1bf..1729b94b2abf 100644
> --- a/drivers/mtd/devices/phram.c
> +++ b/drivers/mtd/devices/phram.c
> @@ -6,14 +6,14 @@
>   * Usage:
>   *
>   * one commend line parameter per device, each in the form:
> - *   phram=<name>,<start>,<len>
> + *   phram=<name>,<start>,<len>[,<erasesize>]
>   * <name> may be up to 63 characters.
> - * <start> and <len> can be octal, decimal or hexadecimal.  If followed
> + * <start>, <len>, and <erasesize> can be octal, decimal or hexadecimal.  If followed
>   * by "ki", "Mi" or "Gi", the numbers will be interpreted as kilo, mega or
> - * gigabytes.
> + * gigabytes. <erasesize> is optional and defaults to PAGE_SIZE.
>   *
>   * Example:
> - *	phram=swap,64Mi,128Mi phram=test,900Mi,1Mi
> + *	phram=swap,64Mi,128Mi phram=test,900Mi,1Mi,64Ki
>   */
>  
>  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> @@ -26,6 +26,7 @@
>  #include <linux/moduleparam.h>
>  #include <linux/slab.h>
>  #include <linux/mtd/mtd.h>
> +#include <asm/div64.h>
>  
>  struct phram_mtd_list {
>  	struct mtd_info mtd;
> @@ -88,7 +89,7 @@ static void unregister_devices(void)
>  	}
>  }
>  
> -static int register_device(char *name, phys_addr_t start, size_t len)
> +static int register_device(char *name, phys_addr_t start, size_t len, uint32_t erasesize)
>  {
>  	struct phram_mtd_list *new;
>  	int ret = -ENOMEM;
> @@ -115,7 +116,7 @@ static int register_device(char *name, phys_addr_t start, size_t len)
>  	new->mtd._write = phram_write;
>  	new->mtd.owner = THIS_MODULE;
>  	new->mtd.type = MTD_RAM;
> -	new->mtd.erasesize = PAGE_SIZE;
> +	new->mtd.erasesize = erasesize;
>  	new->mtd.writesize = 1;
>  
>  	ret = -EAGAIN;
> @@ -204,22 +205,23 @@ static inline void kill_final_newline(char *str)
>  static int phram_init_called;
>  /*
>   * This shall contain the module parameter if any. It is of the form:
> - * - phram=<device>,<address>,<size> for module case
> - * - phram.phram=<device>,<address>,<size> for built-in case
> - * We leave 64 bytes for the device name, 20 for the address and 20 for the
> - * size.
> - * Example: phram.phram=rootfs,0xa0000000,512Mi
> + * - phram=<device>,<address>,<size>[,<erasesize>] for module case
> + * - phram.phram=<device>,<address>,<size>[,<erasesize>] for built-in case
> + * We leave 64 bytes for the device name, 20 for the address , 20 for the
> + * size and 20 for the erasesize.
> + * Example: phram.phram=rootfs,0xa0000000,512Mi,65536
>   */
> -static char phram_paramline[64 + 20 + 20];
> +static char phram_paramline[64 + 20 + 20 + 20];
>  #endif
>  
>  static int phram_setup(const char *val)
>  {
> -	char buf[64 + 20 + 20], *str = buf;
> -	char *token[3];
> +	char buf[64 + 20 + 20 + 20], *str = buf;
> +	char *token[4];
>  	char *name;
>  	uint64_t start;
>  	uint64_t len;
> +	uint64_t erasesize = PAGE_SIZE;
>  	int i, ret;
>  
>  	if (strnlen(val, sizeof(buf)) >= sizeof(buf))
> @@ -228,7 +230,7 @@ static int phram_setup(const char *val)
>  	strcpy(str, val);
>  	kill_final_newline(str);
>  
> -	for (i = 0; i < 3; i++)
> +	for (i = 0; i < 4; i++)
>  		token[i] = strsep(&str, ",");
>  
>  	if (str)
> @@ -253,11 +255,25 @@ static int phram_setup(const char *val)
>  		goto error;
>  	}
>  
> -	ret = register_device(name, start, len);
> +	if (token[3]) {
> +		ret = parse_num64(&erasesize, token[3]);
> +		if (ret) {
> +			parse_err("illegal erasesize\n");
> +			goto error;
> +		}
> +	}
> +
> +	if (len == 0 || erasesize == 0 || erasesize > len
> +	    || erasesize > UINT_MAX || do_div(len, (uint32_t)erasesize) != 0) {
> +		parse_err("illegal erasesize or len\n");
> +		goto error;
> +	}
> +
> +	ret = register_device(name, start, len, (uint32_t)erasesize);
>  	if (ret)
>  		goto error;
>  
> -	pr_info("%s device: %#llx at %#llx\n", name, len, start);
> +	pr_info("%s device: %#llx at %#llx for erasesize %#llx\n", name, len, start, erasesize);
>  	return 0;
>  
>  error:
> @@ -298,7 +314,7 @@ static int phram_param_call(const char *val, const struct kernel_param *kp)
>  }
>  
>  module_param_call(phram, phram_param_call, NULL, NULL, 0200);
> -MODULE_PARM_DESC(phram, "Memory region to map. \"phram=<name>,<start>,<length>\"");
> +MODULE_PARM_DESC(phram, "Memory region to map. \"phram=<name>,<start>,<length>[,<erasesize>]\"");
>  
>  
>  static int __init init_phram(void)

Thanks,
Miquèl

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