Re: [æéäåèååéé] [PATCH v2 7/9] lib/vsprintf: Replace space with '_' before crng is ready

[Yang, Shunyong]

Hi, Andy,

Many thanks for the change. I am on Chinese New Year travel and slow
response. :-)

Thanks.
Shunyong.

On Fri, 2018-02-16 at 23:07 +0200, Andy Shevchenko wrote:
> From: Shunyong Yang <shunyong.yang@xxxxxxxxxxxxxxxx>
> 
> Before crng is ready, output of "%p" composes of "(ptrval)" and
> left padding spaces for alignment as no random address can be
> generated. This seems a little strange when default string width
> is larger than strlen("(ptrval)").
> 
> For example, when irq domain names are built with "%p", the nodes
> under /sys/kernel/debug/irq/domains like this on AArch64 system,
> 
> [root@y irq]# ls domains/
> defaultÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂirqchip@ÂÂÂÂÂÂÂÂ(ptrval)-2
> irqchip@ÂÂÂÂÂÂÂÂ(ptrval)-4ÂÂ\_SB_.TCS0.QIC1ÂÂ\_SB_.TCS0.QIC3
> irqchip@ÂÂÂÂÂÂÂÂ(ptrval)ÂÂirqchip@ÂÂÂÂÂÂÂÂ(ptrval)-3
> \_SB_.TCS0.QIC0ÂÂÂÂÂÂÂÂÂÂÂÂÂ\_SB_.TCS0.QIC2
> 
> The name "irqchip@ÂÂÂÂÂÂÂÂ(ptrval)-2" is not so readable in console
> output.
> 
> This patch replaces space with readable "_" when output needs
> padding.
> Following is the output after applying the patch,
> 
> [root@y domains]# ls
> defaultÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂirqchip@(____ptrval____)-2
> irqchip@(____ptrval____)-4ÂÂ\_SB_.TCS0.QIC1ÂÂ\_SB_.TCS0.QIC3
> irqchip@(____ptrval____)ÂÂirqchip@(____ptrval____)-3ÂÂ\_SB_.TCS0.QIC0
> \_SB_.TCS0.QIC2
> 
> There is same problem in some subsystem's dmesg output. Moreover,
> someone may call "%p" in a similar case. In addition, the timing of
> crng initialization done may vary on different system. So, the change
> is made in vsprintf.c.
> 
> Cc: Joey Zheng <yu.zheng@xxxxxxxxxxxxxxxx>
> Suggested-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Shunyong Yang <shunyong.yang@xxxxxxxxxxxxxxxx>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> ---
> Âlib/vsprintf.c | 3 ++-
> Â1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index 9004bbb3d84d..97be2d07297a 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -1681,12 +1681,13 @@ early_initcall(initialize_ptr_random);
> Â/* Maps a pointer to a 32 bit unique identifier. */
> Âstatic char *ptr_to_id(char *buf, char *end, void *ptr, struct
> printf_spec spec)
> Â{
> +	const char *str = sizeof(ptr) == 8 ? "(____ptrval____)" :
> "(ptrval)";
> Â	unsigned long hashval;
> Â
> Â	if (unlikely(!have_filled_random_ptr_key)) {
> Â		spec.field_width = 2 * sizeof(ptr);
> Â		/* string length must be less than default_width */
> -		return string(buf, end, "(ptrval)", spec);
> +		return string(buf, end, str, spec);
> Â	}
> Â
> Â#ifdef CONFIG_64BIT