/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * Copyright (C) 2005, 2012 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#ifndef R2CLUSTER_MASKLOG_H
#define R2CLUSTER_MASKLOG_H

/*
 * For now this is a trivial wrapper around printk() that gives the critical
 * ability to enable sets of debugging output at run-time.  In the future this
 * will almost certainly be redirected to relayfs so that it can pay a
 * substantially lower heisenberg tax.
 *
 * Callers associate the message with a bitmask and a global bitmask is
 * maintained with help from /proc.  If any of the bits match the message is
 * output.
 *
 * We must have efficient bit tests on i386 and it seems gcc still emits crazy
 * code for the 64bit compare.  It emits very good code for the dual unsigned
 * long tests, though, completely avoiding tests that can never pass if the
 * caller gives a constant bitmask that fills one of the longs with all 0s.  So
 * the desire is to have almost all of the calls decided on by comparing just
 * one of the longs.  This leads to having infrequently given bits that are
 * frequently matched in the high bits.
 *
 * _ERROR and _NOTICE are used for messages that always go to the console and
 * have appropriate KERN_ prefixes.  We wrap these in our function instead of
 * just calling printk() so that this can eventually make its way through
 * relayfs along with the debugging messages.  Everything else gets KERN_DEBUG.
 * The inline tests and macro dance give GCC the opportunity to quite cleverly
 * only emit the appropriage printk() when the caller passes in a constant
 * mask, as is almost always the case.
 *
 * All this bitmask nonsense is managed from the files under
 * /sys/fs/r2cb/logmask/.  Reading the files gives a straightforward
 * indication of which bits are allowed (allow) or denied (off/deny).
 *	ENTRY deny
 *	EXIT deny
 *	TCP off
 *	MSG off
 *	SOCKET off
 *	ERROR allow
 *	NOTICE allow
 *
 * Writing changes the state of a given bit and requires a strictly formatted
 * single write() call:
 *
 *	write(fd, "allow", 5);
 *
 * Echoing allow/deny/off string into the logmask files can flip the bits
 * on or off as expected; here is the bash script for example:
 *
 * log_mask="/sys/fs/r2cb/log_mask"
 * for node in ENTRY EXIT TCP MSG SOCKET ERROR NOTICE; do
 *	echo allow >"$log_mask"/"$node"
 * done
 *
 * The debugfs.ramster tool can also flip the bits with the -l option:
 *
 * debugfs.ramster -l TCP allow
 */

/* for task_struct */
#include <linux/sched.h>

/* bits that are frequently given and infrequently matched in the low word */
/* NOTE: If you add a flag, you need to also update masklog.c! */
#define ML_TCP		0x0000000000000001ULL /* net cluster/tcp.c */
#define ML_MSG		0x0000000000000002ULL /* net network messages */
#define ML_SOCKET	0x0000000000000004ULL /* net socket lifetime */
#define ML_HEARTBEAT	0x0000000000000008ULL /* hb all heartbeat tracking */
#define ML_HB_BIO	0x0000000000000010ULL /* hb io tracing */
#define ML_DLMFS	0x0000000000000020ULL /* dlm user dlmfs */
#define ML_DLM		0x0000000000000040ULL /* dlm general debugging */
#define ML_DLM_DOMAIN	0x0000000000000080ULL /* dlm domain debugging */
#define ML_DLM_THREAD	0x0000000000000100ULL /* dlm domain thread */
#define ML_DLM_MASTER	0x0000000000000200ULL /* dlm master functions */
#define ML_DLM_RECOVERY	0x0000000000000400ULL /* dlm master functions */
#define ML_DLM_GLUE	0x0000000000000800ULL /* ramster dlm glue layer */
#define ML_VOTE		0x0000000000001000ULL /* ramster node messaging  */
#define ML_CONN		0x0000000000002000ULL /* net connection management */
#define ML_QUORUM	0x0000000000004000ULL /* net connection quorum */
#define ML_BASTS	0x0000000000008000ULL /* dlmglue asts and basts */
#define ML_CLUSTER	0x0000000000010000ULL /* cluster stack */

/* bits that are infrequently given and frequently matched in the high word */
#define ML_ERROR	0x1000000000000000ULL /* sent to KERN_ERR */
#define ML_NOTICE	0x2000000000000000ULL /* setn to KERN_NOTICE */
#define ML_KTHREAD	0x4000000000000000ULL /* kernel thread activity */

#define MLOG_INITIAL_AND_MASK (ML_ERROR|ML_NOTICE)
#ifndef MLOG_MASK_PREFIX
#define MLOG_MASK_PREFIX 0
#endif

/*
 * When logging is disabled, force the bit test to 0 for anything other
 * than errors and notices, allowing gcc to remove the code completely.
 * When enabled, allow all masks.
 */
#if defined(CONFIG_RAMSTER_DEBUG_MASKLOG)
#define ML_ALLOWED_BITS (~0)
#else
#define ML_ALLOWED_BITS (ML_ERROR|ML_NOTICE)
#endif

#define MLOG_MAX_BITS 64

struct mlog_bits {
	unsigned long words[MLOG_MAX_BITS / BITS_PER_LONG];
};

extern struct mlog_bits r2_mlog_and_bits, r2_mlog_not_bits;

#if BITS_PER_LONG == 32

#define __mlog_test_u64(mask, bits)			\
	((u32)(mask & 0xffffffff) & bits.words[0] ||	\
	  ((u64)(mask) >> 32) & bits.words[1])
#define __mlog_set_u64(mask, bits) do {			\
	bits.words[0] |= (u32)(mask & 0xffffffff);	\
	bits.words[1] |= (u64)(mask) >> 32;		\
} while (0)
#define __mlog_clear_u64(mask, bits) do {		\
	bits.words[0] &= ~((u32)(mask & 0xffffffff));	\
	bits.words[1] &= ~((u64)(mask) >> 32);		\
} while (0)
#define MLOG_BITS_RHS(mask) {				\
	{						\
		[0] = (u32)(mask & 0xffffffff),		\
		[1] = (u64)(mask) >> 32,		\
	}						\
}

#else /* 32bit long above, 64bit long below */

#define __mlog_test_u64(mask, bits)	((mask) & bits.words[0])
#define __mlog_set_u64(mask, bits) do {		\
	bits.words[0] |= (mask);		\
} while (0)
#define __mlog_clear_u64(mask, bits) do {	\
	bits.words[0] &= ~(mask);		\
} while (0)
#define MLOG_BITS_RHS(mask) { { (mask) } }

#endif

/*
 * smp_processor_id() "helpfully" screams when called outside preemptible
 * regions in current kernels.  sles doesn't have the variants that don't
 * scream.  just do this instead of trying to guess which we're building
 * against.. *sigh*.
 */
#define __mlog_cpu_guess ({		\
	unsigned long _cpu = get_cpu();	\
	put_cpu();			\
	_cpu;				\
})

/* In the following two macros, the whitespace after the ',' just
 * before ##args is intentional. Otherwise, gcc 2.95 will eat the
 * previous token if args expands to nothing.
 */
#define __mlog_printk(level, fmt, args...)				\
	printk(level "(%s,%u,%lu):%s:%d " fmt, current->comm,		\
	       task_pid_nr(current), __mlog_cpu_guess,			\
	       __PRETTY_FUNCTION__, __LINE__ , ##args)

#define mlog(mask, fmt, args...) do {					\
	u64 __m = MLOG_MASK_PREFIX | (mask);				\
	if ((__m & ML_ALLOWED_BITS) &&					\
	    __mlog_test_u64(__m, r2_mlog_and_bits) &&			\
	    !__mlog_test_u64(__m, r2_mlog_not_bits)) {			\
		if (__m & ML_ERROR)					\
			__mlog_printk(KERN_ERR, "ERROR: "fmt , ##args);	\
		else if (__m & ML_NOTICE)				\
			__mlog_printk(KERN_NOTICE, fmt , ##args);	\
		else							\
			__mlog_printk(KERN_INFO, fmt , ##args);		\
	}								\
} while (0)

#define mlog_errno(st) do {						\
	int _st = (st);							\
	if (_st != -ERESTARTSYS && _st != -EINTR &&			\
	    _st != AOP_TRUNCATED_PAGE && _st != -ENOSPC)		\
		mlog(ML_ERROR, "status = %lld\n", (long long)_st);	\
} while (0)

#define mlog_bug_on_msg(cond, fmt, args...) do {			\
	if (cond) {							\
		mlog(ML_ERROR, "bug expression: " #cond "\n");		\
		mlog(ML_ERROR, fmt, ##args);				\
		BUG();							\
	}								\
} while (0)

#include <linux/kobject.h>
#include <linux/sysfs.h>
int r2_mlog_sys_init(struct kset *r2cb_subsys);
void r2_mlog_sys_shutdown(void);

#endif /* R2CLUSTER_MASKLOG_H */