/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * Copyright (C) 2005 Oracle.  All rights reserved.
 */

#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_ratelimited(mask, fmt, ...)                                \
do {                                                                    \
        static DEFINE_RATELIMIT_STATE(_rs,                              \
                                      DEFAULT_RATELIMIT_INTERVAL,       \
                                      DEFAULT_RATELIMIT_BURST);         \
        if (__ratelimit(&_rs))                                          \
                mlog(mask, 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 */