cregit-Linux how code gets into the kernel

Release 4.11 fs/ocfs2/cluster/masklog.h

Directory: fs/ocfs2/cluster
/* -*- 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

__printf(4, 5)
void __mlog_printk(const u64 *m, const char *func, int line,
		   const char *fmt, ...);

/*
 * Testing before the __mlog_printk call lets the compiler eliminate the
 * call completely when (m & ML_ALLOWED_BITS) is 0.
 */

#define mlog(mask, fmt, ...)						\
do {                                                                    \
        u64 _m = MLOG_MASK_PREFIX | (mask);                             \
        if (_m & ML_ALLOWED_BITS)                                       \
                __mlog_printk(&_m, __func__, __LINE__, fmt,             \
                              ##__VA_ARGS__);                           \
} while (0)


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


#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 */

Overall Contributors

PersonTokensPropCommitsCommitProp
Zach Brown26077.15%111.11%
Joe Perches267.72%111.11%
Joel Becker195.64%111.11%
Tao Ma175.04%111.11%
Sunil Mushran123.56%222.22%
Greg Kroah-Hartman10.30%111.11%
Coly Li10.30%111.11%
Andrew Morton10.30%111.11%
Total337100.00%9100.00%
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