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
|
From cdc31409bd4f878577059e70dbd52a28643ec609 Mon Sep 17 00:00:00 2001
From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Wed, 31 Mar 2021 13:53:34 -0300
Subject: [PATCH] linux: Normalize and return timeout on select (BZ #27651)
The commit 2433d39b697, which added time64 support to select, changed
the function to use __NR_pselect6 (or __NR_pelect6_time64) on all
architectures. However, on architectures where the symbol was
implemented with __NR_select the kernel normalizes the passed timeout
instead of return EINVAL. For instance, the input timeval
{ 0, 5000000 } is interpreted as { 5, 0 }.
And as indicated by BZ #27651, this semantic seems to be expected
and changing it results in some performance issues (most likely
the program does not check the return code and keeps issuing
select with unormalized tv_usec argument).
To avoid a different semantic depending whether which syscall the
architecture used to issue, select now always normalize the timeout
input. This is a slight change for some ABIs (for instance aarch64).
Checked on x86_64-linux-gnu and i686-linux-gnu.
---
include/time.h | 5 +++
sunrpc/svcauth_des.c | 1 -
support/Makefile | 2 ++
support/support.h | 8 +++++
support/support_select_modify_timeout.c | 29 ++++++++++++++++
support/support_select_normalize_timeout.c | 29 ++++++++++++++++
sysdeps/unix/sysv/linux/select.c | 40 ++++++++++++++++++----
8 files changed, 123 insertions(+), 8 deletions(-)
create mode 100644 support/support_select_modify_timeout.c
create mode 100644 support/support_select_normalize_timeout.c
diff --git a/include/time.h b/include/time.h
index caf2af5e74..e0636132a6 100644
--- a/include/time.h
+++ b/include/time.h
@@ -502,6 +502,11 @@ time_now (void)
__clock_gettime (TIME_CLOCK_GETTIME_CLOCKID, &ts);
return ts.tv_sec;
}
+
+#define NSEC_PER_SEC 1000000000L /* Nanoseconds per second. */
+#define USEC_PER_SEC 1000000L /* Microseconds per second. */
+#define NSEC_PER_USEC 1000L /* Nanoseconds per microsecond. */
+
#endif
#endif
diff --git a/sunrpc/svcauth_des.c b/sunrpc/svcauth_des.c
index 7607abc818..25a85c9097 100644
--- a/sunrpc/svcauth_des.c
+++ b/sunrpc/svcauth_des.c
@@ -58,7 +58,6 @@
#define debug(msg) /*printf("svcauth_des: %s\n", msg) */
-#define USEC_PER_SEC ((uint32_t) 1000000L)
#define BEFORE(t1, t2) timercmp(t1, t2, <)
/*
diff --git a/support/Makefile b/support/Makefile
index 900e17f94f..1e2fc97ee6 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -68,6 +68,8 @@ libsupport-routines = \
support_quote_string \
support_record_failure \
support_run_diff \
+ support_select_modify_timeout \
+ support_select_normalize_timeout \
support_set_small_thread_stack_size \
support_shared_allocate \
support_small_stack_thread_attribute \
diff --git a/support/support.h b/support/support.h
index e023d00857..f983783d64 100644
--- a/support/support.h
+++ b/support/support.h
@@ -144,6 +144,14 @@ static __inline bool support_path_support_time64 (const char *path)
/* Return true if stat supports nanoseconds resolution. */
extern bool support_stat_nanoseconds (const char *path);
+/* Return true if select modify the timeout to reflect the amount of time
+ no slept. */
+extern bool support_select_modify_timeout (void);
+
+/* Return true if select normalize the timeout input by taking in account
+ tv_usec larger than 1000000. */
+extern bool support_select_normalize_timeout (void);
+
__END_DECLS
#endif /* SUPPORT_H */
diff --git a/support/support_select_modify_timeout.c b/support/support_select_modify_timeout.c
new file mode 100644
index 0000000000..d70a5a5068
--- /dev/null
+++ b/support/support_select_modify_timeout.c
@@ -0,0 +1,29 @@
+/* Return whether select modify the timeout.
+ Copyright (C) 2021 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <stdbool.h>
+
+bool
+support_select_modify_timeout (void)
+{
+#ifdef __linux__
+ return true;
+#else
+ return false;
+#endif
+}
diff --git a/support/support_select_normalize_timeout.c b/support/support_select_normalize_timeout.c
new file mode 100644
index 0000000000..447e3ec3e3
--- /dev/null
+++ b/support/support_select_normalize_timeout.c
@@ -0,0 +1,29 @@
+/* Return whether select normalize the timeout.
+ Copyright (C) 2021 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <stdbool.h>
+
+bool
+support_select_normalize_timeout (void)
+{
+#ifdef __linux__
+ return true;
+#else
+ return false;
+#endif
+}
diff --git a/sysdeps/unix/sysv/linux/select.c b/sysdeps/unix/sysv/linux/select.c
index 415aa87d3c..d075270ff4 100644
--- a/sysdeps/unix/sysv/linux/select.c
+++ b/sysdeps/unix/sysv/linux/select.c
@@ -33,12 +33,34 @@ int
__select64 (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
struct __timeval64 *timeout)
{
- struct __timespec64 ts64, *pts64 = NULL;
- if (timeout != NULL)
+ __time64_t s = timeout != NULL ? timeout->tv_sec : 0;
+ int32_t us = timeout != NULL ? timeout->tv_usec : 0;
+ int32_t ns;
+
+ if (s < 0 || us < 0)
+ return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);
+
+ /* Normalize the timeout, as legacy Linux __NR_select and __NR__newselect.
+ Different than syscall, it also handle possible overflow. */
+ if (us / USEC_PER_SEC > INT64_MAX - s)
{
- ts64 = timeval64_to_timespec64 (*timeout);
- pts64 = &ts64;
+ s = INT64_MAX;
+ ns = NSEC_PER_SEC - 1;
}
+ else
+ {
+ s += us / USEC_PER_SEC;
+ us = us % USEC_PER_SEC;
+ ns = us * NSEC_PER_USEC;
+ }
+
+ struct __timespec64 ts64, *pts64 = NULL;
+ if (timeout != NULL)
+ {
+ ts64.tv_sec = s;
+ ts64.tv_nsec = ns;
+ pts64 = &ts64;
+ }
#ifndef __NR_pselect6_time64
# define __NR_pselect6_time64 __NR_pselect6
@@ -52,10 +74,13 @@ __select64 (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
(though the pselect() glibc call suppresses this behavior).
Since select() on Linux has the same behavior as the pselect6
syscall, we update the timeout here. */
- if (r == 0 || errno != ENOSYS)
+ if (r >= 0 || errno != ENOSYS)
{
if (timeout != NULL)
- TIMEVAL_TO_TIMESPEC (timeout, &ts64);
+ {
+ timeout->tv_sec = ts64.tv_sec;
+ timeout->tv_usec = ts64.tv_nsec / NSEC_PER_USEC;
+ }
return r;
}
@@ -71,7 +96,8 @@ __select64 (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
__set_errno (EINVAL);
return -1;
}
- ts32 = valid_timespec64_to_timespec (ts64);
+ ts32.tv_sec = s;
+ ts32.tv_nsec = ns;
pts32 = &ts32;
}
# ifndef __ASSUME_PSELECT
--
2.27.0
|
