Commit 0b74d4d7 authored by Petr Mladek's avatar Petr Mladek
Browse files

vsprintf: Consolidate handling of unknown pointer specifiers 

There are few printk formats that make sense only with two or more
specifiers. Also some specifiers make sense only when a kernel feature
is enabled.

The handling of unknown specifiers is inconsistent and not helpful.
Using WARN() looks like an overkill for this type of error. pr_warn()
is not good either. It would by handled via printk_safe buffer and
it might be hard to match it with the problematic string.

A reasonable compromise seems to be writing the unknown format specifier
into the original string with a question mark, for example (%pC?).
It should be self-explaining enough. Note that it is in brackets
to follow the (null) style.

Note that it introduces a warning about that test_hashed() function
is unused. It is going to be used again by a later patch.

Link: http://lkml.kernel.org/r/20190417115350.20479-8-pmladek@suse.com


To: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Tobin C . Harding" <me@tobin.cc>
Cc: Joe Perches <joe@perches.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: linux-kernel@vger.kernel.org
Reviewed-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
parent 798cc27a

lib/test_printf.c

+1 −2
Original line number Diff line number Diff line
@@ -462,8 +462,7 @@ struct_rtc_time(void) 
		.tm_year = 118,

	};



	test_hashed("%pt", &tm);



	test("(%ptR?)", "%pt", &tm);

	test("2018-11-26T05:35:43", "%ptR", &tm);

	test("0118-10-26T05:35:43", "%ptRr", &tm);

	test("05:35:43|2018-11-26", "%ptRt|%ptRd", &tm, &tm);

lib/vsprintf.c

+17 −11
Original line number Diff line number Diff line
@@ -1435,6 +1435,8 @@ static noinline_for_stack 
char *ip_addr_string(char *buf, char *end, const void *ptr,

		     struct printf_spec spec, const char *fmt)

{

	char *err_fmt_msg;



	switch (fmt[1]) {

	case '6':

		return ip6_addr_string(buf, end, ptr, spec, fmt);
@@ -1457,7 +1459,8 @@ char *ip_addr_string(char *buf, char *end, const void *ptr, 
		}}

	}



	return ptr_to_id(buf, end, ptr, spec);

	err_fmt_msg = fmt[0] == 'i' ? "(%pi?)" : "(%pI?)";

	return string_nocheck(buf, end, err_fmt_msg, spec);

}



static noinline_for_stack
@@ -1585,7 +1588,7 @@ char *netdev_bits(char *buf, char *end, const void *addr, 
		size = sizeof(netdev_features_t);

		break;

	default:

		return ptr_to_id(buf, end, addr, spec);

		return string_nocheck(buf, end, "(%pN?)", spec);

	}



	return special_hex_number(buf, end, num, size);
@@ -1689,7 +1692,7 @@ char *time_and_date(char *buf, char *end, void *ptr, struct printf_spec spec, 
	case 'R':

		return rtc_str(buf, end, (const struct rtc_time *)ptr, fmt);

	default:

		return ptr_to_id(buf, end, ptr, spec);

		return string_nocheck(buf, end, "(%ptR?)", spec);

	}

}
@@ -1697,7 +1700,10 @@ static noinline_for_stack 
char *clock(char *buf, char *end, struct clk *clk, struct printf_spec spec,

	    const char *fmt)

{

	if (!IS_ENABLED(CONFIG_HAVE_CLK) || !clk)

	if (!IS_ENABLED(CONFIG_HAVE_CLK))

		return string_nocheck(buf, end, "(%pC?)", spec);



	if (!clk)

		return string(buf, end, NULL, spec);



	switch (fmt[1]) {
@@ -1706,7 +1712,7 @@ char *clock(char *buf, char *end, struct clk *clk, struct printf_spec spec, 
#ifdef CONFIG_COMMON_CLK

		return string(buf, end, __clk_get_name(clk), spec);

#else

		return ptr_to_id(buf, end, clk, spec);

		return string_nocheck(buf, end, "(%pC?)", spec);

#endif

	}

}
@@ -1739,7 +1745,8 @@ char *format_flags(char *buf, char *end, unsigned long flags, 
}



static noinline_for_stack

char *flags_string(char *buf, char *end, void *flags_ptr, const char *fmt)

char *flags_string(char *buf, char *end, void *flags_ptr,

		   struct printf_spec spec, const char *fmt)

{

	unsigned long flags;

	const struct trace_print_flags *names;
@@ -1760,8 +1767,7 @@ char *flags_string(char *buf, char *end, void *flags_ptr, const char *fmt) 
		names = gfpflag_names;

		break;

	default:

		WARN_ONCE(1, "Unsupported flags modifier: %c\n", fmt[1]);

		return buf;

		return string_nocheck(buf, end, "(%pG?)", spec);

	}



	return format_flags(buf, end, flags, names);
@@ -1817,7 +1823,7 @@ char *device_node_string(char *buf, char *end, struct device_node *dn, 
	str_spec.field_width = -1;



	if (!IS_ENABLED(CONFIG_OF))

		return string_nocheck(buf, end, "(!OF)", spec);

		return string_nocheck(buf, end, "(%pOF?)", spec);



	if ((unsigned long)dn < PAGE_SIZE)

		return string_nocheck(buf, end, "(null)", spec);
@@ -1896,7 +1902,7 @@ static char *kobject_string(char *buf, char *end, void *ptr, 
		return device_node_string(buf, end, ptr, spec, fmt + 1);

	}



	return ptr_to_id(buf, end, ptr, spec);

	return string_nocheck(buf, end, "(%pO?)", spec);

}



/*
@@ -2091,7 +2097,7 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, 
#endif



	case 'G':

		return flags_string(buf, end, ptr, fmt);

		return flags_string(buf, end, ptr, spec, fmt);

	case 'O':

		return kobject_string(buf, end, ptr, spec, fmt);

	case 'x':

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