summaryrefslogtreecommitdiffstats
path: root/fs/xfs/support/ktrace.c
blob: 2d494c26717f47e14aa1fb90aeb65d75ec5f6abc (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
/*
 * Copyright (c) 2000-2003,2005 Silicon Graphics, Inc.
 * 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.
 *
 * This program is distributed in the hope that it would 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 the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include <xfs.h>

static kmem_zone_t *ktrace_hdr_zone;
static kmem_zone_t *ktrace_ent_zone;
static int          ktrace_zentries;

void __init
ktrace_init(int zentries)
{
	ktrace_zentries = roundup_pow_of_two(zentries);

	ktrace_hdr_zone = kmem_zone_init(sizeof(ktrace_t),
					"ktrace_hdr");
	ASSERT(ktrace_hdr_zone);

	ktrace_ent_zone = kmem_zone_init(ktrace_zentries
					* sizeof(ktrace_entry_t),
					"ktrace_ent");
	ASSERT(ktrace_ent_zone);
}

void __exit
ktrace_uninit(void)
{
	kmem_zone_destroy(ktrace_hdr_zone);
	kmem_zone_destroy(ktrace_ent_zone);
}

/*
 * ktrace_alloc()
 *
 * Allocate a ktrace header and enough buffering for the given
 * number of entries. Round the number of entries up to a
 * power of 2 so we can do fast masking to get the index from
 * the atomic index counter.
 */
ktrace_t *
ktrace_alloc(int nentries, unsigned int __nocast sleep)
{
	ktrace_t        *ktp;
	ktrace_entry_t  *ktep;
	int		entries;

	ktp = (ktrace_t*)kmem_zone_alloc(ktrace_hdr_zone, sleep);

	if (ktp == (ktrace_t*)NULL) {
		/*
		 * KM_SLEEP callers don't expect failure.
		 */
		if (sleep & KM_SLEEP)
			panic("ktrace_alloc: NULL memory on KM_SLEEP request!");

		return NULL;
	}

	/*
	 * Special treatment for buffers with the ktrace_zentries entries
	 */
	entries = roundup_pow_of_two(nentries);
	if (entries == ktrace_zentries) {
		ktep = (ktrace_entry_t*)kmem_zone_zalloc(ktrace_ent_zone,
							    sleep);
	} else {
		ktep = (ktrace_entry_t*)kmem_zalloc((entries * sizeof(*ktep)),
							    sleep | KM_LARGE);
	}

	if (ktep == NULL) {
		/*
		 * KM_SLEEP callers don't expect failure.
		 */
		if (sleep & KM_SLEEP)
			panic("ktrace_alloc: NULL memory on KM_SLEEP request!");

		kmem_free(ktp);

		return NULL;
	}

	ktp->kt_entries  = ktep;
	ktp->kt_nentries = entries;
	ASSERT(is_power_of_2(entries));
	ktp->kt_index_mask = entries - 1;
	atomic_set(&ktp->kt_index, 0);
	ktp->kt_rollover = 0;
	return ktp;
}


/*
 * ktrace_free()
 *
 * Free up the ktrace header and buffer.  It is up to the caller
 * to ensure that no-one is referencing it.
 */
void
ktrace_free(ktrace_t *ktp)
{
	if (ktp == (ktrace_t *)NULL)
		return;

	/*
	 * Special treatment for the Vnode trace buffer.
	 */
	if (ktp->kt_nentries == ktrace_zentries)
		kmem_zone_free(ktrace_ent_zone, ktp->kt_entries);
	else
		kmem_free(ktp->kt_entries);

	kmem_zone_free(ktrace_hdr_zone, ktp);
}


/*
 * Enter the given values into the "next" entry in the trace buffer.
 * kt_index is always the index of the next entry to be filled.
 */
void
ktrace_enter(
	ktrace_t        *ktp,
	void            *val0,
	void            *val1,
	void            *val2,
	void            *val3,
	void            *val4,
	void            *val5,
	void            *val6,
	void            *val7,
	void            *val8,
	void            *val9,
	void            *val10,
	void            *val11,
	void            *val12,
	void            *val13,
	void            *val14,
	void            *val15)
{
	int             index;
	ktrace_entry_t  *ktep;

	ASSERT(ktp != NULL);

	/*
	 * Grab an entry by pushing the index up to the next one.
	 */
	index = atomic_add_return(1, &ktp->kt_index);
	index = (index - 1) & ktp->kt_index_mask;
	if (!ktp->kt_rollover && index == ktp->kt_nentries - 1)
		ktp->kt_rollover = 1;

	ASSERT((index >= 0) && (index < ktp->kt_nentries));

	ktep = &(ktp->kt_entries[index]);

	ktep->val[0]  = val0;
	ktep->val[1]  = val1;
	ktep->val[2]  = val2;
	ktep->val[3]  = val3;
	ktep->val[4]  = val4;
	ktep->val[5]  = val5;
	ktep->val[6]  = val6;
	ktep->val[7]  = val7;
	ktep->val[8]  = val8;
	ktep->val[9]  = val9;
	ktep->val[10] = val10;
	ktep->val[11] = val11;
	ktep->val[12] = val12;
	ktep->val[13] = val13;
	ktep->val[14] = val14;
	ktep->val[15] = val15;
}

/*
 * Return the number of entries in the trace buffer.
 */
int
ktrace_nentries(
	ktrace_t        *ktp)
{
	int	index;
	if (ktp == NULL)
		return 0;

	index = atomic_read(&ktp->kt_index) & ktp->kt_index_mask;
	return (ktp->kt_rollover ? ktp->kt_nentries : index);
}

/*
 * ktrace_first()
 *
 * This is used to find the start of the trace buffer.
 * In conjunction with ktrace_next() it can be used to
 * iterate through the entire trace buffer.  This code does
 * not do any locking because it is assumed that it is called
 * from the debugger.
 *
 * The caller must pass in a pointer to a ktrace_snap
 * structure in which we will keep some state used to
 * iterate through the buffer.  This state must not touched
 * by any code outside of this module.
 */
ktrace_entry_t *
ktrace_first(ktrace_t   *ktp, ktrace_snap_t     *ktsp)
{
	ktrace_entry_t  *ktep;
	int             index;
	int             nentries;

	if (ktp->kt_rollover)
		index = atomic_read(&ktp->kt_index) & ktp->kt_index_mask;
	else
		index = 0;

	ktsp->ks_start = index;
	ktep = &(ktp->kt_entries[index]);

	nentries = ktrace_nentries(ktp);
	index++;
	if (index < nentries) {
		ktsp->ks_index = index;
	} else {
		ktsp->ks_index = 0;
		if (index > nentries)
			ktep = NULL;
	}
	return ktep;
}

/*
 * ktrace_next()
 *
 * This is used to iterate through the entries of the given
 * trace buffer.  The caller must pass in the ktrace_snap_t
 * structure initialized by ktrace_first().  The return value
 * will be either a pointer to the next ktrace_entry or NULL
 * if all of the entries have been traversed.
 */
ktrace_entry_t *
ktrace_next(
	ktrace_t        *ktp,
	ktrace_snap_t   *ktsp)
{
	int             index;
	ktrace_entry_t  *ktep;

	index = ktsp->ks_index;
	if (index == ktsp->ks_start) {
		ktep = NULL;
	} else {
		ktep = &ktp->kt_entries[index];
	}

	index++;
	if (index == ktrace_nentries(ktp)) {
		ktsp->ks_index = 0;
	} else {
		ktsp->ks_index = index;
	}

	return ktep;
}

/*
 * ktrace_skip()
 *
 * Skip the next "count" entries and return the entry after that.
 * Return NULL if this causes us to iterate past the beginning again.
 */
ktrace_entry_t *
ktrace_skip(
	ktrace_t        *ktp,
	int             count,
	ktrace_snap_t   *ktsp)
{
	int             index;
	int             new_index;
	ktrace_entry_t  *ktep;
	int             nentries = ktrace_nentries(ktp);

	index = ktsp->ks_index;
	new_index = index + count;
	while (new_index >= nentries) {
		new_index -= nentries;
	}
	if (index == ktsp->ks_start) {
		/*
		 * We've iterated around to the start, so we're done.
		 */
		ktep = NULL;
	} else if ((new_index < index) && (index < ktsp->ks_index)) {
		/*
		 * We've skipped past the start again, so we're done.
		 */
		ktep = NULL;
		ktsp->ks_index = ktsp->ks_start;
	} else {
		ktep = &(ktp->kt_entries[new_index]);
		new_index++;
		if (new_index == nentries) {
			ktsp->ks_index = 0;
		} else {
			ktsp->ks_index = new_index;
		}
	}
	return ktep;
}
OpenPOWER on IntegriCloud