BTW, this is what I had in mind:
This patch adds the ability to add arbitrary types to vsprintf rather than
adding every type to pointer().
Future users include reiserfs and btrfs, where it's much more conventient
to print messages with common data structures with a simple printk rather
than a series of them. It makes the code much cleaner and easier to read.
This functionality is accessed via the e-prefixed versions of the usual
string formatting and printing routines by using "%pe<letter>" as a format
string. Callers establish a set of operations and pass it as the first
artugment. I expect this will typically be hidden behind a helper function,
much like reiserfs_warning, etc does now.
Example, eprintk(btrfs_printf_ops, "Invalid key %pek\n", key);
or more likely: btrfs_warning(sb, "Invalid key %pek\n", key);
instead of printk("Invalid key [%llu %d %llu]\n",
le64_to_cpu(key->objectid), key->type,
le64_to_cpu(key->offset));
It's even more useful when larger and/or multiple objects need to be printed.
Another advantage is smaller code size due to smaller strings and less
calculation surrounding each print site. I haven't converted btrfs yet
and reiserfs already uses a similar mechanism, so I don't have hard numbers
for this.
The only exception to the e-prefix rule is kasprintf, etc, which will
retain the k prefix. It's sort of arbitrary, since I would have assumed
those functions would retain a ka-prefix, but that isn't the case.
No additional code changes are required - this is for extensions only.
Signed-off-by: Jeff Mahoney <jeffm@xxxxxxxx>
---
include/linux/kernel.h | 36 ++++++++++++++++
include/linux/printf.h | 11 +++++
kernel/printk.c | 25 ++++++++++-
lib/kasprintf.c | 28 +++++++++++-
lib/vsprintf.c | 107 +++++++++++++++++++++++++++++++++++++++++++------
5 files changed, 191 insertions(+), 16 deletions(-)
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -114,6 +114,7 @@ extern int console_printk[];
struct completion;
struct pt_regs;
struct user;
+struct printf_operations;
#ifdef CONFIG_PREEMPT_VOLUNTARY
extern int _cond_resched(void);
@@ -177,19 +178,42 @@ extern int strict_strtoull(const char *,
extern int strict_strtoll(const char *, unsigned int, long long *);
extern int sprintf(char * buf, const char * fmt, ...)
__attribute__ ((format (printf, 2, 3)));
+extern int esprintf(const struct printf_operations *ops, char *buf,
+ const char *fmt, ...)
+ __attribute__ ((format (printf, 3, 4)));
extern int vsprintf(char *buf, const char *, va_list)
__attribute__ ((format (printf, 2, 0)));
+extern int evsprintf(const struct printf_operations *ops, char *buf,
+ const char *, va_list)
+ __attribute__ ((format (printf, 3, 0)));
extern int snprintf(char * buf, size_t size, const char * fmt, ...)
__attribute__ ((format (printf, 3, 4)));
+extern int esnprintf(const struct printf_operations *ops, char *buf,
+ size_t size, const char *fmt, ...)
+ __attribute__ ((format (printf, 4, 5)));
extern int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
__attribute__ ((format (printf, 3, 0)));
+extern int evsnprintf(const struct printf_operations *ops, char *buf,
+ size_t size, const char *fmt, va_list args)
+ __attribute__ ((format (printf, 4, 0)));
extern int scnprintf(char * buf, size_t size, const char * fmt, ...)
__attribute__ ((format (printf, 3, 4)));
+extern int escnprintf(const struct printf_operations *ops, char *buf,
+ size_t size, const char *fmt, ...)
+ __attribute__ ((format (printf, 4, 5)));
extern int vscnprintf(char *buf, size_t size, const char *fmt, va_list args)
__attribute__ ((format (printf, 3, 0)));
+extern int evscnprintf(const struct printf_operations *ops, char *buf,
+ size_t size, const char *fmt, va_list args)
+ __attribute__ ((format (printf, 4, 0)));
extern char *kasprintf(gfp_t gfp, const char *fmt, ...)
__attribute__ ((format (printf, 2, 3)));
+extern char *keasprintf(const struct printf_operations *ops, gfp_t gfp,
+ const char *fmt, ...)
+ __attribute__ ((format (printf, 3, 4)));
extern char *kvasprintf(gfp_t gfp, const char *fmt, va_list args);
+extern char *kevasprintf(const struct printf_operations *ops, gfp_t gfp,
+ const char *fmt, va_list args);
extern int sscanf(const char *, const char *, ...)
__attribute__ ((format (scanf, 2, 3)));
@@ -233,6 +257,12 @@ extern struct pid *session_of_pgrp(struc
#define FW_INFO "[Firmware Info]: "
#ifdef CONFIG_PRINTK
+asmlinkage int evprintk(const struct printf_operations *ops,
+ const char *fmt, va_list args)
+ __attribute__ ((format (printf, 2, 0)));
+asmlinkage int eprintk(const struct printf_operations *ops,
+ const char *fmt, ...)
+ __attribute__ ((format (printf, 2, 3))) __cold;
asmlinkage int vprintk(const char *fmt, va_list args)
__attribute__ ((format (printf, 1, 0)));
asmlinkage int printk(const char * fmt, ...)
@@ -250,6 +280,12 @@ static inline int printk(const char *s,
__attribute__ ((format (printf, 1, 2)));
static inline int __cold printk(const char *s, ...) { return 0; }
static inline int printk_ratelimit(void) { return 0; }
+static inline int evprintk(const struct printf_operations *ops,
+ const char *s, va_list args)
+ __attribute__ ((format (printf, 2, 0)));
+static inline int __cold eprintk(const struct printf_operations *ops,
+ const char *s, ...)
+ __attribute__ ((format (printf, 2, 3)));
static inline bool printk_timed_ratelimit(unsigned long *caller_jiffies, \
unsigned int interval_msec) \
{ return false; }
--- /dev/null
+++ b/include/linux/printf.h
@@ -0,0 +1,11 @@
+#ifndef _PRINTF_H_
+#define _PRINTF_H_
+
+struct printf_operations {
+ char operator;
+ char * (*handler)(const char *fmt, char *buf, char *end,
+ const void *ptr, int field_width, int precision,
+ int flags);
+};
+
+#endif
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -567,6 +567,20 @@ asmlinkage int printk(const char *fmt, .
return r;
}
+asmlinkage int eprintk(const struct printf_operations *ops,
+ const char *fmt, ...)
+{
+ va_list args;
+ int r;
+
+ va_start(args, fmt);
+ r = evprintk(ops, fmt, args);
+ va_end(args);
+
+ return r;
+}
+EXPORT_SYMBOL(eprintk);
+
/* cpu currently holding logbuf_lock */
static volatile unsigned int printk_cpu = UINT_MAX;
@@ -622,7 +636,8 @@ static int recursion_bug;
static int new_text_line = 1;
static char printk_buf[1024];
-asmlinkage int vprintk(const char *fmt, va_list args)
+asmlinkage int evprintk(const struct printf_operations *ops,
+ const char *fmt, va_list args)
{
int printed_len = 0;
int current_log_level = default_message_loglevel;
@@ -665,7 +680,7 @@ asmlinkage int vprintk(const char *fmt,
printed_len = strlen(recursion_bug_msg);
}
/* Emit the output into the temporary buffer */
- printed_len += vscnprintf(printk_buf + printed_len,
+ printed_len += evscnprintf(ops, printk_buf + printed_len,
sizeof(printk_buf) - printed_len, fmt, args);
@@ -737,6 +752,12 @@ out_restore_irqs:
preempt_enable();
return printed_len;
}
+EXPORT_SYMBOL(evprintk);
+
+asmlinkage int vprintk(const char *fmt, va_list args)
+{
+ return evprintk(NULL, fmt, args);
+}
EXPORT_SYMBOL(printk);
EXPORT_SYMBOL(vprintk);
--- a/lib/kasprintf.c
+++ b/lib/kasprintf.c
@@ -8,26 +8,34 @@
#include <linux/module.h>
#include <linux/types.h>
#include <linux/string.h>
+#include <linux/printf.h>
/* Simplified asprintf. */
-char *kvasprintf(gfp_t gfp, const char *fmt, va_list ap)
+char *kevasprintf(const struct printf_operations *ops, gfp_t gfp,
+ const char *fmt, va_list ap)
{
unsigned int len;
char *p;
va_list aq;
va_copy(aq, ap);
- len = vsnprintf(NULL, 0, fmt, aq);
+ len = evsnprintf(ops, NULL, 0, fmt, aq);
va_end(aq);
p = kmalloc(len+1, gfp);
if (!p)
return NULL;
- vsnprintf(p, len+1, fmt, ap);
+ evsnprintf(ops, p, len+1, fmt, ap);
return p;
}
+EXPORT_SYMBOL(kevasprintf);
+
+char *kvasprintf(gfp_t gfp, const char *fmt, va_list ap)
+{
+ return kevasprintf(NULL, gfp, fmt, ap);
+}
EXPORT_SYMBOL(kvasprintf);
char *kasprintf(gfp_t gfp, const char *fmt, ...)
@@ -42,3 +50,17 @@ char *kasprintf(gfp_t gfp, const char *f
return p;
}
EXPORT_SYMBOL(kasprintf);
+
+char *keasprintf(const struct printf_operations *ops, gfp_t gfp,
+ const char *fmt, ...)
+{
+ va_list ap;
+ char *p;
+
+ va_start(ap, fmt);
+ p = kevasprintf(ops, gfp, fmt, ap);
+ va_end(ap);
+
+ return p;
+}
+EXPORT_SYMBOL(keasprintf);
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -25,6 +25,7 @@
#include <linux/kallsyms.h>
#include <linux/uaccess.h>
#include <linux/ioport.h>
+#include <linux/printf.h>
#include <asm/page.h> /* for PAGE_SIZE */
#include <asm/div64.h>
@@ -641,6 +642,22 @@ static char *ip4_addr_string(char *buf,
return string(buf, end, ip4_addr, field_width, precision, flags & ~SPECIAL);
}
+static char *epointer(const char *fmt, char *buf, char *end, const void *ptr,
+ int field_width, int precision, int flags,
+ const struct printf_operations *ops)
+{
+ const struct printf_operations *op;
+ if (!*fmt)
+ return NULL;
+
+ for (op = ops; op && op->handler; op++) {
+ if (*fmt == op->operator)
+ return op->handler(fmt + 1, buf, end, ptr, field_width,
+ precision, flags);
+ }
+ return NULL;
+}
+
/*
* Show a '%p' thing. A kernel extension is that the '%p' is followed
* by an extra set of alphanumeric characters that are extended format
@@ -663,8 +680,11 @@ static char *ip4_addr_string(char *buf,
* function pointers are really function descriptors, which contain a
* pointer to the real address.
*/
-static char *pointer(const char *fmt, char *buf, char *end, void *ptr, int field_width, int precision, int flags)
+static char *pointer(const char *fmt, char *buf, char *end, void *ptr,
+ int field_width, int precision, int flags,
+ const struct printf_operations *ops)
{
+ char *p;
if (!ptr)
return string(buf, end, "(null)", field_width, precision, flags);
@@ -691,6 +711,10 @@ static char *pointer(const char *fmt, ch
return ip4_addr_string(buf, end, ptr, field_width, precision, flags);
flags &= ~SPECIAL;
break;
+ case 'e':
+ if ((p = epointer(fmt + 1, buf, end, ptr, field_width,
+ precision, flags, ops)))
+ return p;
}
flags |= SMALL;
if (field_width == -1) {
@@ -704,6 +728,7 @@ static char *pointer(const char *fmt, ch
* vsnprintf - Format a string and place it in a buffer
* @buf: The buffer to place the result into
* @size: The size of the buffer, including the trailing null space
+ * @ops: An optional array of operations for special %p handling
* @fmt: The format string to use
* @args: Arguments for the format string
*
@@ -723,7 +748,8 @@ static char *pointer(const char *fmt, ch
* Call this function if you are already dealing with a va_list.
* You probably want snprintf() instead.
*/
-int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
+int evsnprintf(const struct printf_operations *ops, char *buf,
+ size_t size, const char *fmt, va_list args)
{
unsigned long long num;
int base;
@@ -849,7 +875,8 @@ int vsnprintf(char *buf, size_t size, co
case 'p':
str = pointer(fmt+1, str, end,
va_arg(args, void *),
- field_width, precision, flags);
+ field_width, precision, flags,
+ ops);
/* Skip all alphanumeric pointer suffixes */
while (isalnum(fmt[1]))
fmt++;
@@ -937,6 +964,12 @@ int vsnprintf(char *buf, size_t size, co
/* the trailing null byte doesn't count towards the total */
return str-buf;
}
+EXPORT_SYMBOL(evsnprintf);
+
+int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
+{
+ return evsnprintf(NULL, buf, size, fmt, args);
+}
EXPORT_SYMBOL(vsnprintf);
/**
@@ -955,13 +988,19 @@ EXPORT_SYMBOL(vsnprintf);
*
* See the vsnprintf() documentation for format string extensions over C99.
*/
-int vscnprintf(char *buf, size_t size, const char *fmt, va_list args)
+int evscnprintf(const struct printf_operations *ops, char *buf,
+ size_t size, const char *fmt, va_list args)
{
- int i;
-
- i=vsnprintf(buf,size,fmt,args);
+ int i = evsnprintf(ops, buf, size, fmt, args);
return (i >= size) ? (size - 1) : i;
}
+EXPORT_SYMBOL(evscnprintf);
+
+int vscnprintf(char *buf, size_t size, const char *fmt, va_list args)
+{
+ return evscnprintf(NULL, buf, size, fmt, args);
+}
+
EXPORT_SYMBOL(vscnprintf);
/**
@@ -978,18 +1017,31 @@ EXPORT_SYMBOL(vscnprintf);
*
* See the vsnprintf() documentation for format string extensions over C99.
*/
-int snprintf(char * buf, size_t size, const char *fmt, ...)
+int snprintf(char *buf, size_t size, const char *fmt, ...)
{
va_list args;
int i;
va_start(args, fmt);
- i=vsnprintf(buf,size,fmt,args);
+ i = vsnprintf(buf, size, fmt, args);
va_end(args);
return i;
}
EXPORT_SYMBOL(snprintf);
+int esnprintf(const struct printf_operations *ops, char *buf,
+ size_t size, const char *fmt, ...)
+{
+ va_list args;
+ int i;
+
+ va_start(args, fmt);
+ i = evsnprintf(ops, buf, size, fmt, args);
+ va_end(args);
+ return i;
+}
+EXPORT_SYMBOL(esnprintf);
+
/**
* scnprintf - Format a string and place it in a buffer
* @buf: The buffer to place the result into
@@ -1001,7 +1053,7 @@ EXPORT_SYMBOL(snprintf);
* the trailing '\0'. If @size is <= 0 the function returns 0.
*/
-int scnprintf(char * buf, size_t size, const char *fmt, ...)
+int scnprintf(char *buf, size_t size, const char *fmt, ...)
{
va_list args;
int i;
@@ -1013,6 +1065,19 @@ int scnprintf(char * buf, size_t size, c
}
EXPORT_SYMBOL(scnprintf);
+int escnprintf(const struct printf_operations *ops, char *buf,
+ size_t size, const char *fmt, ...)
+{
+ va_list args;
+ int i;
+
+ va_start(args, fmt);
+ i = evsnprintf(ops, buf, size, fmt, args);
+ va_end(args);
+ return (i >= size) ? (size - 1) : i;
+}
+EXPORT_SYMBOL(escnprintf);
+
/**
* vsprintf - Format a string and place it in a buffer
* @buf: The buffer to place the result into
@@ -1034,6 +1099,13 @@ int vsprintf(char *buf, const char *fmt,
}
EXPORT_SYMBOL(vsprintf);
+int evsprintf(const struct printf_operations *ops, char *buf,
+ const char *fmt, va_list args)
+{
+ return evsnprintf(ops, buf, INT_MAX, fmt, args);
+}
+EXPORT_SYMBOL(evsprintf);
+
/**
* sprintf - Format a string and place it in a buffer
* @buf: The buffer to place the result into
@@ -1052,12 +1124,25 @@ int sprintf(char * buf, const char *fmt,
int i;
va_start(args, fmt);
- i=vsnprintf(buf, INT_MAX, fmt, args);
+ i = vsnprintf(buf, INT_MAX, fmt, args);
va_end(args);
return i;
}
EXPORT_SYMBOL(sprintf);
+int esprintf(const struct printf_operations *ops, char *buf,
+ const char *fmt, ...)
+{
+ va_list args;
+ int i;
+
+ va_start(args, fmt);
+ i = evsnprintf(ops, buf, INT_MAX, fmt, args);
+ va_end(args);
+ return i;
+}
+EXPORT_SYMBOL(esprintf);
+
/**
* vsscanf - Unformat a buffer into a list of arguments
* @buf: input buffer
--
Jeff Mahoney
SUSE Labs
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