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-rw-r--r--arch/parisc/lib/debuglocks.c277
1 files changed, 0 insertions, 277 deletions
diff --git a/arch/parisc/lib/debuglocks.c b/arch/parisc/lib/debuglocks.c
deleted file mode 100644
index 1b33fe6e5b7a..000000000000
--- a/arch/parisc/lib/debuglocks.c
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@@ -1,277 +0,0 @@
1/*
2 * Debugging versions of SMP locking primitives.
3 *
4 * Copyright (C) 2004 Thibaut VARENE <varenet@parisc-linux.org>
5 *
6 * Some code stollen from alpha & sparc64 ;)
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 *
22 * We use pdc_printf() throughout the file for all output messages, to avoid
23 * losing messages because of disabled interrupts. Since we're using these
24 * messages for debugging purposes, it makes sense not to send them to the
25 * linux console.
26 */
27
28
29#include <linux/config.h>
30#include <linux/kernel.h>
31#include <linux/sched.h>
32#include <linux/spinlock.h>
33#include <linux/hardirq.h> /* in_interrupt() */
34#include <asm/system.h>
35#include <asm/hardirq.h> /* in_interrupt() */
36#include <asm/pdc.h>
37
38#undef INIT_STUCK
39#define INIT_STUCK 1L << 30
40
41#ifdef CONFIG_DEBUG_SPINLOCK
42
43
44void _dbg_spin_lock(spinlock_t * lock, const char *base_file, int line_no)
45{
46 volatile unsigned int *a;
47 long stuck = INIT_STUCK;
48 void *inline_pc = __builtin_return_address(0);
49 unsigned long started = jiffies;
50 int printed = 0;
51 int cpu = smp_processor_id();
52
53try_again:
54
55 /* Do the actual locking */
56 /* <T-Bone> ggg: we can't get stuck on the outter loop?
57 * <ggg> T-Bone: We can hit the outer loop
58 * alot if multiple CPUs are constantly racing for a lock
59 * and the backplane is NOT fair about which CPU sees
60 * the update first. But it won't hang since every failed
61 * attempt will drop us back into the inner loop and
62 * decrement `stuck'.
63 * <ggg> K-class and some of the others are NOT fair in the HW
64 * implementation so we could see false positives.
65 * But fixing the lock contention is easier than
66 * fixing the HW to be fair.
67 * <tausq> __ldcw() returns 1 if we get the lock; otherwise we
68 * spin until the value of the lock changes, or we time out.
69 */
70 mb();
71 a = __ldcw_align(lock);
72 while (stuck && (__ldcw(a) == 0))
73 while ((*a == 0) && --stuck);
74 mb();
75
76 if (unlikely(stuck <= 0)) {
77 pdc_printf(
78 "%s:%d: spin_lock(%s/%p) stuck in %s at %p(%d)"
79 " owned by %s:%d in %s at %p(%d)\n",
80 base_file, line_no, lock->module, lock,
81 current->comm, inline_pc, cpu,
82 lock->bfile, lock->bline, lock->task->comm,
83 lock->previous, lock->oncpu);
84 stuck = INIT_STUCK;
85 printed = 1;
86 goto try_again;
87 }
88
89 /* Exiting. Got the lock. */
90 lock->oncpu = cpu;
91 lock->previous = inline_pc;
92 lock->task = current;
93 lock->bfile = (char *)base_file;
94 lock->bline = line_no;
95
96 if (unlikely(printed)) {
97 pdc_printf(
98 "%s:%d: spin_lock grabbed in %s at %p(%d) %ld ticks\n",
99 base_file, line_no, current->comm, inline_pc,
100 cpu, jiffies - started);
101 }
102}
103
104void _dbg_spin_unlock(spinlock_t * lock, const char *base_file, int line_no)
105{
106 CHECK_LOCK(lock);
107 volatile unsigned int *a;
108 mb();
109 a = __ldcw_align(lock);
110 if (unlikely((*a != 0) && lock->babble)) {
111 lock->babble--;
112 pdc_printf(
113 "%s:%d: spin_unlock(%s:%p) not locked\n",
114 base_file, line_no, lock->module, lock);
115 }
116 *a = 1;
117 mb();
118}
119
120int _dbg_spin_trylock(spinlock_t * lock, const char *base_file, int line_no)
121{
122 int ret;
123 volatile unsigned int *a;
124 mb();
125 a = __ldcw_align(lock);
126 ret = (__ldcw(a) != 0);
127 mb();
128 if (ret) {
129 lock->oncpu = smp_processor_id();
130 lock->previous = __builtin_return_address(0);
131 lock->task = current;
132 } else {
133 lock->bfile = (char *)base_file;
134 lock->bline = line_no;
135 }
136 return ret;
137}
138
139#endif /* CONFIG_DEBUG_SPINLOCK */
140
141#ifdef CONFIG_DEBUG_RWLOCK
142
143/* Interrupts trouble detailed explanation, thx Grant:
144 *
145 * o writer (wants to modify data) attempts to acquire the rwlock
146 * o He gets the write lock.
147 * o Interupts are still enabled, we take an interrupt with the
148 * write still holding the lock.
149 * o interrupt handler tries to acquire the rwlock for read.
150 * o deadlock since the writer can't release it at this point.
151 *
152 * In general, any use of spinlocks that competes between "base"
153 * level and interrupt level code will risk deadlock. Interrupts
154 * need to be disabled in the base level routines to avoid it.
155 * Or more precisely, only the IRQ the base level routine
156 * is competing with for the lock. But it's more efficient/faster
157 * to just disable all interrupts on that CPU to guarantee
158 * once it gets the lock it can release it quickly too.
159 */
160
161void _dbg_write_lock(rwlock_t *rw, const char *bfile, int bline)
162{
163 void *inline_pc = __builtin_return_address(0);
164 unsigned long started = jiffies;
165 long stuck = INIT_STUCK;
166 int printed = 0;
167 int cpu = smp_processor_id();
168
169 if(unlikely(in_interrupt())) { /* acquiring write lock in interrupt context, bad idea */
170 pdc_printf("write_lock caller: %s:%d, IRQs enabled,\n", bfile, bline);
171 BUG();
172 }
173
174 /* Note: if interrupts are disabled (which is most likely), the printk
175 will never show on the console. We might need a polling method to flush
176 the dmesg buffer anyhow. */
177
178retry:
179 _raw_spin_lock(&rw->lock);
180
181 if(rw->counter != 0) {
182 /* this basically never happens */
183 _raw_spin_unlock(&rw->lock);
184
185 stuck--;
186 if ((unlikely(stuck <= 0)) && (rw->counter < 0)) {
187 pdc_printf(
188 "%s:%d: write_lock stuck on writer"
189 " in %s at %p(%d) %ld ticks\n",
190 bfile, bline, current->comm, inline_pc,
191 cpu, jiffies - started);
192 stuck = INIT_STUCK;
193 printed = 1;
194 }
195 else if (unlikely(stuck <= 0)) {
196 pdc_printf(
197 "%s:%d: write_lock stuck on reader"
198 " in %s at %p(%d) %ld ticks\n",
199 bfile, bline, current->comm, inline_pc,
200 cpu, jiffies - started);
201 stuck = INIT_STUCK;
202 printed = 1;
203 }
204
205 while(rw->counter != 0);
206
207 goto retry;
208 }
209
210 /* got it. now leave without unlocking */
211 rw->counter = -1; /* remember we are locked */
212
213 if (unlikely(printed)) {
214 pdc_printf(
215 "%s:%d: write_lock grabbed in %s at %p(%d) %ld ticks\n",
216 bfile, bline, current->comm, inline_pc,
217 cpu, jiffies - started);
218 }
219}
220
221int _dbg_write_trylock(rwlock_t *rw, const char *bfile, int bline)
222{
223#if 0
224 void *inline_pc = __builtin_return_address(0);
225 int cpu = smp_processor_id();
226#endif
227
228 if(unlikely(in_interrupt())) { /* acquiring write lock in interrupt context, bad idea */
229 pdc_printf("write_lock caller: %s:%d, IRQs enabled,\n", bfile, bline);
230 BUG();
231 }
232
233 /* Note: if interrupts are disabled (which is most likely), the printk
234 will never show on the console. We might need a polling method to flush
235 the dmesg buffer anyhow. */
236
237 _raw_spin_lock(&rw->lock);
238
239 if(rw->counter != 0) {
240 /* this basically never happens */
241 _raw_spin_unlock(&rw->lock);
242 return 0;
243 }
244
245 /* got it. now leave without unlocking */
246 rw->counter = -1; /* remember we are locked */
247#if 0
248 pdc_printf("%s:%d: try write_lock grabbed in %s at %p(%d)\n",
249 bfile, bline, current->comm, inline_pc, cpu);
250#endif
251 return 1;
252}
253
254void _dbg_read_lock(rwlock_t * rw, const char *bfile, int bline)
255{
256#if 0
257 void *inline_pc = __builtin_return_address(0);
258 unsigned long started = jiffies;
259 int cpu = smp_processor_id();
260#endif
261 unsigned long flags;
262
263 local_irq_save(flags);
264 _raw_spin_lock(&rw->lock);
265
266 rw->counter++;
267#if 0
268 pdc_printf(
269 "%s:%d: read_lock grabbed in %s at %p(%d) %ld ticks\n",
270 bfile, bline, current->comm, inline_pc,
271 cpu, jiffies - started);
272#endif
273 _raw_spin_unlock(&rw->lock);
274 local_irq_restore(flags);
275}
276
277#endif /* CONFIG_DEBUG_RWLOCK */
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