lib/vsprintf: Replace space with '_' before crng is ready

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.

Suggested-by: Rasmus Villemoes <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
To: "Tobin C . Harding" <[email protected]>
To: [email protected]
To: Joe Perches <[email protected]>
To: [email protected]
To: Andrew Morton <[email protected]>
Cc: Joey Zheng <[email protected]>
Signed-off-by: Shunyong Yang <[email protected]>
Signed-off-by: Andy Shevchenko <[email protected]>
Signed-off-by: Petr Mladek <[email protected]>

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 9004bbb3d84d955bb7f79af746ae8ee1f9c33cfe..97be2d07297a70ff1fa841f2c401af2bf4985a35 100644 (file)
--- 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