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Linux/fs/ocfs2/cluster/masklog.h

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  1 /* -*- mode: c; c-basic-offset: 8; -*-
  2  * vim: noexpandtab sw=8 ts=8 sts=0:
  3  *
  4  * Copyright (C) 2005 Oracle.  All rights reserved.
  5  *
  6  * This program is free software; you can redistribute it and/or
  7  * modify it under the terms of the GNU General Public
  8  * License as published by the Free Software Foundation; either
  9  * version 2 of the License, or (at your option) any later version.
 10  *
 11  * This program is distributed in the hope that it will be useful,
 12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 14  * General Public License for more details.
 15  *
 16  * You should have received a copy of the GNU General Public
 17  * License along with this program; if not, write to the
 18  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 19  * Boston, MA 021110-1307, USA.
 20  */
 21 
 22 #ifndef O2CLUSTER_MASKLOG_H
 23 #define O2CLUSTER_MASKLOG_H
 24 
 25 /*
 26  * For now this is a trivial wrapper around printk() that gives the critical
 27  * ability to enable sets of debugging output at run-time.  In the future this
 28  * will almost certainly be redirected to relayfs so that it can pay a
 29  * substantially lower heisenberg tax.
 30  *
 31  * Callers associate the message with a bitmask and a global bitmask is
 32  * maintained with help from /proc.  If any of the bits match the message is
 33  * output.
 34  *
 35  * We must have efficient bit tests on i386 and it seems gcc still emits crazy
 36  * code for the 64bit compare.  It emits very good code for the dual unsigned
 37  * long tests, though, completely avoiding tests that can never pass if the
 38  * caller gives a constant bitmask that fills one of the longs with all 0s.  So
 39  * the desire is to have almost all of the calls decided on by comparing just
 40  * one of the longs.  This leads to having infrequently given bits that are
 41  * frequently matched in the high bits.
 42  *
 43  * _ERROR and _NOTICE are used for messages that always go to the console and
 44  * have appropriate KERN_ prefixes.  We wrap these in our function instead of
 45  * just calling printk() so that this can eventually make its way through
 46  * relayfs along with the debugging messages.  Everything else gets KERN_DEBUG.
 47  * The inline tests and macro dance give GCC the opportunity to quite cleverly
 48  * only emit the appropriage printk() when the caller passes in a constant
 49  * mask, as is almost always the case.
 50  *
 51  * All this bitmask nonsense is managed from the files under
 52  * /sys/fs/o2cb/logmask/.  Reading the files gives a straightforward
 53  * indication of which bits are allowed (allow) or denied (off/deny).
 54  *      ENTRY deny
 55  *      EXIT deny
 56  *      TCP off
 57  *      MSG off
 58  *      SOCKET off
 59  *      ERROR allow
 60  *      NOTICE allow
 61  *
 62  * Writing changes the state of a given bit and requires a strictly formatted
 63  * single write() call:
 64  *
 65  *      write(fd, "allow", 5);
 66  *
 67  * Echoing allow/deny/off string into the logmask files can flip the bits
 68  * on or off as expected; here is the bash script for example:
 69  *
 70  * log_mask="/sys/fs/o2cb/log_mask"
 71  * for node in ENTRY EXIT TCP MSG SOCKET ERROR NOTICE; do
 72  *      echo allow >"$log_mask"/"$node"
 73  * done
 74  *
 75  * The debugfs.ocfs2 tool can also flip the bits with the -l option:
 76  *
 77  * debugfs.ocfs2 -l TCP allow
 78  */
 79 
 80 /* for task_struct */
 81 #include <linux/sched.h>
 82 
 83 /* bits that are frequently given and infrequently matched in the low word */
 84 /* NOTE: If you add a flag, you need to also update masklog.c! */
 85 #define ML_TCP          0x0000000000000001ULL /* net cluster/tcp.c */
 86 #define ML_MSG          0x0000000000000002ULL /* net network messages */
 87 #define ML_SOCKET       0x0000000000000004ULL /* net socket lifetime */
 88 #define ML_HEARTBEAT    0x0000000000000008ULL /* hb all heartbeat tracking */
 89 #define ML_HB_BIO       0x0000000000000010ULL /* hb io tracing */
 90 #define ML_DLMFS        0x0000000000000020ULL /* dlm user dlmfs */
 91 #define ML_DLM          0x0000000000000040ULL /* dlm general debugging */
 92 #define ML_DLM_DOMAIN   0x0000000000000080ULL /* dlm domain debugging */
 93 #define ML_DLM_THREAD   0x0000000000000100ULL /* dlm domain thread */
 94 #define ML_DLM_MASTER   0x0000000000000200ULL /* dlm master functions */
 95 #define ML_DLM_RECOVERY 0x0000000000000400ULL /* dlm master functions */
 96 #define ML_DLM_GLUE     0x0000000000000800ULL /* ocfs2 dlm glue layer */
 97 #define ML_VOTE         0x0000000000001000ULL /* ocfs2 node messaging  */
 98 #define ML_CONN         0x0000000000002000ULL /* net connection management */
 99 #define ML_QUORUM       0x0000000000004000ULL /* net connection quorum */
100 #define ML_BASTS        0x0000000000008000ULL /* dlmglue asts and basts */
101 #define ML_CLUSTER      0x0000000000010000ULL /* cluster stack */
102 
103 /* bits that are infrequently given and frequently matched in the high word */
104 #define ML_ERROR        0x1000000000000000ULL /* sent to KERN_ERR */
105 #define ML_NOTICE       0x2000000000000000ULL /* setn to KERN_NOTICE */
106 #define ML_KTHREAD      0x4000000000000000ULL /* kernel thread activity */
107 
108 #define MLOG_INITIAL_AND_MASK (ML_ERROR|ML_NOTICE)
109 #ifndef MLOG_MASK_PREFIX
110 #define MLOG_MASK_PREFIX 0
111 #endif
112 
113 /*
114  * When logging is disabled, force the bit test to 0 for anything other
115  * than errors and notices, allowing gcc to remove the code completely.
116  * When enabled, allow all masks.
117  */
118 #if defined(CONFIG_OCFS2_DEBUG_MASKLOG)
119 #define ML_ALLOWED_BITS ~0
120 #else
121 #define ML_ALLOWED_BITS (ML_ERROR|ML_NOTICE)
122 #endif
123 
124 #define MLOG_MAX_BITS 64
125 
126 struct mlog_bits {
127         unsigned long words[MLOG_MAX_BITS / BITS_PER_LONG];
128 };
129 
130 extern struct mlog_bits mlog_and_bits, mlog_not_bits;
131 
132 #if BITS_PER_LONG == 32
133 
134 #define __mlog_test_u64(mask, bits)                     \
135         ( (u32)(mask & 0xffffffff) & bits.words[0] ||   \
136           ((u64)(mask) >> 32) & bits.words[1] )
137 #define __mlog_set_u64(mask, bits) do {                 \
138         bits.words[0] |= (u32)(mask & 0xffffffff);      \
139         bits.words[1] |= (u64)(mask) >> 32;             \
140 } while (0)
141 #define __mlog_clear_u64(mask, bits) do {               \
142         bits.words[0] &= ~((u32)(mask & 0xffffffff));   \
143         bits.words[1] &= ~((u64)(mask) >> 32);          \
144 } while (0)
145 #define MLOG_BITS_RHS(mask) {                           \
146         {                                               \
147                 [0] = (u32)(mask & 0xffffffff),         \
148                 [1] = (u64)(mask) >> 32,                \
149         }                                               \
150 }
151 
152 #else /* 32bit long above, 64bit long below */
153 
154 #define __mlog_test_u64(mask, bits)     ((mask) & bits.words[0])
155 #define __mlog_set_u64(mask, bits) do {         \
156         bits.words[0] |= (mask);                \
157 } while (0)
158 #define __mlog_clear_u64(mask, bits) do {       \
159         bits.words[0] &= ~(mask);               \
160 } while (0)
161 #define MLOG_BITS_RHS(mask) { { (mask) } }
162 
163 #endif
164 
165 __printf(4, 5)
166 void __mlog_printk(const u64 *m, const char *func, int line,
167                    const char *fmt, ...);
168 
169 /*
170  * Testing before the __mlog_printk call lets the compiler eliminate the
171  * call completely when (m & ML_ALLOWED_BITS) is 0.
172  */
173 #define mlog(mask, fmt, ...)                                            \
174 do {                                                                    \
175         u64 _m = MLOG_MASK_PREFIX | (mask);                             \
176         if (_m & ML_ALLOWED_BITS)                                       \
177                 __mlog_printk(&_m, __func__, __LINE__, fmt,             \
178                               ##__VA_ARGS__);                           \
179 } while (0)
180 
181 #define mlog_errno(st) ({                                               \
182         int _st = (st);                                                 \
183         if (_st != -ERESTARTSYS && _st != -EINTR &&                     \
184             _st != AOP_TRUNCATED_PAGE && _st != -ENOSPC &&              \
185             _st != -EDQUOT)                                             \
186                 mlog(ML_ERROR, "status = %lld\n", (long long)_st);      \
187         _st;                                                            \
188 })
189 
190 #define mlog_bug_on_msg(cond, fmt, args...) do {                        \
191         if (cond) {                                                     \
192                 mlog(ML_ERROR, "bug expression: " #cond "\n");          \
193                 mlog(ML_ERROR, fmt, ##args);                            \
194                 BUG();                                                  \
195         }                                                               \
196 } while (0)
197 
198 #include <linux/kobject.h>
199 #include <linux/sysfs.h>
200 int mlog_sys_init(struct kset *o2cb_subsys);
201 void mlog_sys_shutdown(void);
202 
203 #endif /* O2CLUSTER_MASKLOG_H */
204 

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