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git.ipfire.org Git - thirdparty/glibc.git/blob - hurd/hurdlock.c
1 /* Hurd helpers for lowlevellocks.
2 Copyright (C) 1999-2019 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
21 #include <hurd/hurd.h>
26 /* Convert an absolute timeout in nanoseconds to a relative
27 timeout in milliseconds. */
28 static inline int __attribute__ ((gnu_inline
))
29 compute_reltime (const struct timespec
*abstime
, clockid_t clk
)
32 __clock_gettime (clk
, &ts
);
34 ts
.tv_sec
= abstime
->tv_sec
- ts
.tv_sec
;
35 ts
.tv_nsec
= abstime
->tv_nsec
- ts
.tv_nsec
;
40 ts
.tv_nsec
+= 1000000000;
43 return ts
.tv_sec
< 0 ? -1 : (int)(ts
.tv_sec
* 1000 + ts
.tv_nsec
/ 1000000);
47 __lll_abstimed_wait (void *ptr
, int val
,
48 const struct timespec
*tsp
, int flags
, int clk
)
50 int mlsec
= compute_reltime (tsp
, clk
);
51 return mlsec
< 0 ? KERN_TIMEDOUT
: lll_timed_wait (ptr
, val
, mlsec
, flags
);
55 __lll_abstimed_xwait (void *ptr
, int lo
, int hi
,
56 const struct timespec
*tsp
, int flags
, int clk
)
58 int mlsec
= compute_reltime (tsp
, clk
);
59 return mlsec
< 0 ? KERN_TIMEDOUT
: lll_timed_xwait (ptr
, lo
, hi
, mlsec
,
64 __lll_abstimed_lock (void *ptr
,
65 const struct timespec
*tsp
, int flags
, int clk
)
67 if (lll_trylock (ptr
) == 0)
72 if (atomic_exchange_acq ((int *)ptr
, 2) == 0)
74 else if (tsp
->tv_nsec
< 0 || tsp
->tv_nsec
>= 1000000000)
77 int mlsec
= compute_reltime (tsp
, clk
);
78 if (mlsec
< 0 || lll_timed_wait (ptr
, 2, mlsec
, flags
) == KERN_TIMEDOUT
)
85 /* Test if a given process id is still valid. */
89 task_t task
= __pid2task (pid
);
90 if (task
== MACH_PORT_NULL
)
93 __mach_port_deallocate (__mach_task_self (), task
);
97 /* Robust locks have currently no support from the kernel; they
98 are simply implemented with periodic polling. When sleeping, the
99 maximum blocking time is determined by this constant. */
100 #define MAX_WAIT_TIME 1500
103 __lll_robust_lock (void *ptr
, int flags
)
105 int *iptr
= (int *)ptr
;
106 int id
= __getpid ();
110 /* Try to set the lock word to our PID if it's clear. Otherwise,
111 mark it as having waiters. */
115 if (!val
&& atomic_compare_and_exchange_bool_acq (iptr
, id
, 0) == 0)
117 else if (atomic_compare_and_exchange_bool_acq (iptr
,
118 val
| LLL_WAITERS
, val
) == 0)
122 for (id
|= LLL_WAITERS
; ; )
125 if (!val
&& atomic_compare_and_exchange_bool_acq (iptr
, id
, 0) == 0)
127 else if (val
&& !valid_pid (val
& LLL_OWNER_MASK
))
129 if (atomic_compare_and_exchange_bool_acq (iptr
, id
, val
) == 0)
134 lll_timed_wait (iptr
, val
, wait_time
, flags
);
135 if (wait_time
< MAX_WAIT_TIME
)
142 __lll_robust_abstimed_lock (void *ptr
,
143 const struct timespec
*tsp
, int flags
, int clk
)
145 int *iptr
= (int *)ptr
;
146 int id
= __getpid ();
153 if (!val
&& atomic_compare_and_exchange_bool_acq (iptr
, id
, 0) == 0)
155 else if (atomic_compare_and_exchange_bool_acq (iptr
,
156 val
| LLL_WAITERS
, val
) == 0)
160 for (id
|= LLL_WAITERS
; ; )
163 if (!val
&& atomic_compare_and_exchange_bool_acq (iptr
, id
, 0) == 0)
165 else if (val
&& !valid_pid (val
& LLL_OWNER_MASK
))
167 if (atomic_compare_and_exchange_bool_acq (iptr
, id
, val
) == 0)
172 int mlsec
= compute_reltime (tsp
, clk
);
175 else if (mlsec
> wait_time
)
178 int res
= lll_timed_wait (iptr
, val
, mlsec
, flags
);
179 if (res
== KERN_TIMEDOUT
)
181 else if (wait_time
< MAX_WAIT_TIME
)
188 __lll_robust_trylock (void *ptr
)
190 int *iptr
= (int *)ptr
;
191 int id
= __getpid ();
192 unsigned int val
= *iptr
;
196 if (atomic_compare_and_exchange_bool_acq (iptr
, id
, 0) == 0)
199 else if (!valid_pid (val
& LLL_OWNER_MASK
)
200 && atomic_compare_and_exchange_bool_acq (iptr
, id
, val
) == 0)
207 __lll_robust_unlock (void *ptr
, int flags
)
209 unsigned int val
= atomic_load_relaxed ((unsigned int *)ptr
);
212 if (val
& LLL_WAITERS
)
214 lll_set_wake (ptr
, 0, flags
);
217 else if (atomic_compare_exchange_weak_release ((unsigned int *)ptr
, &val
, 0))