Assertions, pre-conditions, post-conditions, invariants.

Data Structures
struct	m0_panic_ctx

Macros
#define	M0_ASSERT_OFF   (0)
#define	M0_ASSERT_EX_ON   (0)
#define	likely(x)   __builtin_expect(!!(x), 1)
#define	unlikely(x)   __builtin_expect(!!(x), 0)
#define	_0C(exp)

Enumerations
enum	{ BACKTRACE_DEPTH_MAX = 256 }

Functions
void	m0_panic (const struct m0_panic_ctx *ctx,...)
M0_INTERNAL void	m0_panic_only (const struct m0_panic_ctx *ctx,...)
void	m0_backtrace (void)
M0_INTERNAL void	m0__assertion_hook (void)
M0_INTERNAL void	m0_arch_panic (const struct m0_panic_ctx *ctx, va_list ap) __attribute__((noreturn))
M0_INTERNAL void	m0_arch_backtrace (void)
	__attribute__ ((format(printf, 1, 2))) static inline void printf_check(const char *fmt
M0_INTERNAL void	m0_debugger_invoke (void)

Variables
static int	m0_panic_delay_msec = 110
M0_EXTERN char *	m0_debugger_args [4]

Detailed Description

User space m0_arch_panic() implementation.

Macro Definition Documentation

_0C

#define _0C

(

exp

)

Value:

({                                                          \
        bool __exp = (exp);                                 \
        if (!M0_ASSERT_OFF) {                               \
                if (__exp) {                                \
                        m0_failed_condition = NULL;         \
                } else {                                    \
                        if (m0_failed_condition == NULL)    \
                                m0_failed_condition = #exp; \
                        m0__assertion_hook();               \
                }                                           \
        }                                                   \
        __exp;                                              \
})

A macro to remember failed invariant conjunct.

This macro is used like the following:

bool foo_invariant(const struct foo *f)
{
        return _0C(f != NULL) && _0C(f->f_ref > 0) &&
                m0_tl_forall(bar, s, &foo->f_list, _0C(b->b_parent == f) &&
                                  _0C(b->b_nr < f->f_nr));
}

If during invocation of foo_invariant() one of invariant conjuncts evaluates to false, the string representing this conjunct is stored in m0_failed_condition and printed by m0_panic(). This simplifies debugging.

Note

This macro expressly and deliberately violates "M0_" prefix requirement to reduce verbosity.

This compiles to "exp" if M0_ASSERT_OFF is true.

Definition at line 311 of file assert.h.

likely

#define likely

(

x

)

__builtin_expect(!!(x), 1)

Definition at line 70 of file assert.h.

M0_ASSERT_EX_ON

#define M0_ASSERT_EX_ON   (0)

Definition at line 62 of file assert.h.

M0_ASSERT_OFF

#define M0_ASSERT_OFF   (0)

Definition at line 56 of file assert.h.

unlikely

#define unlikely

(

x

)

__builtin_expect(!!(x), 0)

Definition at line 74 of file assert.h.

Enumeration Type Documentation

anonymous enum

anonymous enum

Enumerator
BACKTRACE_DEPTH_MAX

Definition at line 48 of file uassert.c.

Function Documentation

__attribute__()

__attribute__

(

(format(printf, 1, 2))

)

const

Check printf format string against parameters.

This function does nothing except checking that the format string matches the rest of arguments and producing a compilation warning in case it doesn't. It is handy in macros which accept printf-like parameters with a format string.

For example usage, refer to M0_TRACE_POINT() macro

m0__assertion_hook()

M0_INTERNAL void m0__assertion_hook

(

void

)

Called by _0C() when invariant conjunct fails.

Useful thing to put a breakpoint at.

Definition at line 78 of file assert.c.

m0_arch_backtrace()

void m0_arch_backtrace

(

void

)

Definition at line 40 of file kassert.c.

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m0_arch_panic()

M0_INTERNAL void m0_arch_panic	(	const struct m0_panic_ctx *	c,
		va_list	ap
	)

Simple user space panic function: issue diagnostics to the stderr, flush the stream, optionally print the backtrace and abort(3) the program.

Stack back-trace printing uses GNU extensions to the libc, declared in <execinfo.h> header (checked for by ./configure). Object files should be compiled with -rdynamic for this to work in the presence of dynamic linking.

Definition at line 45 of file kassert.c.

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m0_backtrace()

void m0_backtrace

(

void

)

Definition at line 72 of file assert.c.

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m0_debugger_invoke()

M0_INTERNAL void m0_debugger_invoke

(

void

)

Invokes a debugger, if possible.

This can be used for debugging purposes. Note that this function can return.

In user space, this function invokes the debugger specified in M0_DEBUGGER environment variable.

In Linux kernel this breaks in kgdb, if configured.

Definition at line 67 of file kassert.c.

m0_panic()

void m0_panic	(	const struct m0_panic_ctx *	ctx,
			...
	)

Panic function.

Display panic message and abort program execution.

Parameters

ctx	panic context
...	arguments for printf format string m0_panic_ctx::pc_fmt

Definition at line 40 of file assert.c.

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m0_panic_only()

M0_INTERNAL void m0_panic_only	(	const struct m0_panic_ctx *	ctx,
			...
	)

Abort program execution.

This function is similar to m0_panic(), but doesn't call M0_LOG() nor checks for a double panic. Therefore, it can be called on early stages of initialisation.

Definition at line 63 of file assert.c.

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Variable Documentation

m0_debugger_args

M0_EXTERN char* m0_debugger_args[4]

Definition at line 50 of file uassert.c.

m0_panic_delay_msec

int m0_panic_delay_msec = 110

static

Definition at line 38 of file kassert.c.