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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 /*
166  * smp_processor_id() "helpfully" screams when called outside preemptible
167  * regions in current kernels. sles doesn't have the variants that don't
168  * scream. just do this instead of trying to guess which we're building
169  * against.. *sigh*.
170  */
171 #define __mlog_cpu_guess ({ \
172  unsigned long _cpu = get_cpu(); \
173  put_cpu(); \
174  _cpu; \
175 })
176 
177 /* In the following two macros, the whitespace after the ',' just
178  * before ##args is intentional. Otherwise, gcc 2.95 will eat the
179  * previous token if args expands to nothing.
180  */
181 #define __mlog_printk(level, fmt, args...) \
182  printk(level "(%s,%u,%lu):%s:%d " fmt, current->comm, \
183  task_pid_nr(current), __mlog_cpu_guess, \
184  __PRETTY_FUNCTION__, __LINE__ , ##args)
185 
186 #define mlog(mask, fmt, args...) do { \
187  u64 __m = MLOG_MASK_PREFIX | (mask); \
188  if ((__m & ML_ALLOWED_BITS) && \
189  __mlog_test_u64(__m, mlog_and_bits) && \
190  !__mlog_test_u64(__m, mlog_not_bits)) { \
191  if (__m & ML_ERROR) \
192  __mlog_printk(KERN_ERR, "ERROR: "fmt , ##args); \
193  else if (__m & ML_NOTICE) \
194  __mlog_printk(KERN_NOTICE, fmt , ##args); \
195  else __mlog_printk(KERN_INFO, fmt , ##args); \
196  } \
197 } while (0)
198 
199 #define mlog_errno(st) do { \
200  int _st = (st); \
201  if (_st != -ERESTARTSYS && _st != -EINTR && \
202  _st != AOP_TRUNCATED_PAGE && _st != -ENOSPC) \
203  mlog(ML_ERROR, "status = %lld\n", (long long)_st); \
204 } while (0)
205 
206 #define mlog_bug_on_msg(cond, fmt, args...) do { \
207  if (cond) { \
208  mlog(ML_ERROR, "bug expression: " #cond "\n"); \
209  mlog(ML_ERROR, fmt, ##args); \
210  BUG(); \
211  } \
212 } while (0)
213 
214 #include <linux/kobject.h>
215 #include <linux/sysfs.h>
216 int mlog_sys_init(struct kset *o2cb_subsys);
217 void mlog_sys_shutdown(void);
218 
219 #endif /* O2CLUSTER_MASKLOG_H */