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: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>

diff --git a/lib/test_printf.c b/lib/test_printf.c
index 659b6cc..250ee86 100644 (file)
--- a/lib/test_printf.c
+++ b/lib/test_printf.c
@@ -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);

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 9817d17..f471a65 100644 (file)
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -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':