text: /* -*- mode: c; c-basic-offset: 8; -*-
   * vim: noexpandtab sw=8 ts=8 sts=0:
   *
   * Copyright (C) 2005 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 O2CLUSTER_MASKLOG_H
  #define O2CLUSTER_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/o2cb/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/o2cb/log_mask"
   * for node in ENTRY EXIT TCP MSG SOCKET ERROR NOTICE; do
   *	echo allow >"$log_mask"/"$node"
   * done
   *
   * The debugfs.ocfs2 tool can also flip the bits with the -l option:
   *
   * debugfs.ocfs2 -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 /* ocfs2 dlm glue layer */
  #define ML_VOTE		0x0000000000001000ULL /* ocfs2 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_OCFS2_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 mlog_and_bits, 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, mlog_and_bits) &&			\
  	    !__mlog_test_u64(__m, 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 mlog_sys_init(struct kset *o2cb_subsys);
  void mlog_sys_shutdown(void);
  
  #endif /* O2CLUSTER_MASKLOG_H */
  