Messages in this thread Patch in this message | | | From | Andy Shevchenko <> | Subject | [PATCH v2 7/9] lib/vsprintf: Replace space with '_' before crng is ready | Date | Fri, 16 Feb 2018 23:07:09 +0200 |
| |
From: Shunyong Yang <shunyong.yang@hxt-semitech.com>
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/ default irqchip@ (ptrval)-2 irqchip@ (ptrval)-4 \_SB_.TCS0.QIC1 \_SB_.TCS0.QIC3 irqchip@ (ptrval) irqchip@ (ptrval)-3 \_SB_.TCS0.QIC0 \_SB_.TCS0.QIC2
The name "irqchip@ (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 default irqchip@(____ptrval____)-2 irqchip@(____ptrval____)-4 \_SB_.TCS0.QIC1 \_SB_.TCS0.QIC3 irqchip@(____ptrval____) irqchip@(____ptrval____)-3 \_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@hxt-semitech.com> Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Shunyong Yang <shunyong.yang@hxt-semitech.com> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> --- lib/vsprintf.c | 3 ++- 1 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); /* Maps a pointer to a 32 bit unique identifier. */ static char *ptr_to_id(char *buf, char *end, void *ptr, struct printf_spec spec) { + const char *str = sizeof(ptr) == 8 ? "(____ptrval____)" : "(ptrval)"; unsigned long hashval; if (unlikely(!have_filled_random_ptr_key)) { spec.field_width = 2 * sizeof(ptr); /* string length must be less than default_width */ - return string(buf, end, "(ptrval)", spec); + return string(buf, end, str, spec); } #ifdef CONFIG_64BIT -- 2.15.1
| |