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
|
From: Richard Braun <rbraun@sceen.net>
Subject: Fix timeout handling in _hurd_select
Rely on servers to implement timeouts, so that very short values (including
0) don't make mach_msg return before valid replies can be received. The
purpose of this scheme is to guarantee a full client-server round-trip,
whatever the timeout value.
This change depends on the new io_select_timeout RPC being implemented by
servers.
* hurd/Makefile (user-interfaces): Add io_reply and io_request.
* hurd/hurdselect.c: Include <sys/time.h>, <hurd/io_request.h> and <limits.h>.
(_hurd_select): Replace the call to __io_select with either __io_select_request
or __io_select_timeout_request, depending on the timeout. Count the number of
ready descriptors (replies for which at least one type bit is set). Implement
the timeout locally when there is no file descriptor.
TODO: see XXX
---
hurd/Makefile | 3 +-
hurd/hurdselect.c | 116 +++++++++++++++++++++++++++++++++++------------------
2 files changed, 79 insertions(+), 40 deletions(-)
--- a/hurd/Makefile
+++ b/hurd/Makefile
@@ -37,7 +37,8 @@ user-interfaces := $(addprefix hurd/,\
process process_request \
msg msg_reply msg_request \
exec exec_startup crash interrupt \
- fs fsys io term tioctl socket ifsock \
+ fs fsys io io_reply io_request \
+ term tioctl socket ifsock \
login password pfinet \
)
server-interfaces := hurd/msg faultexc
--- a/hurd/hurdselect.c
+++ b/hurd/hurdselect.c
@@ -16,14 +16,17 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
+#include <sys/time.h>
#include <sys/types.h>
#include <sys/poll.h>
#include <hurd.h>
#include <hurd/fd.h>
+#include <hurd/io_request.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <stdint.h>
+#include <limits.h>
/* All user select types. */
#define SELECT_ALL (SELECT_READ | SELECT_WRITE | SELECT_URG)
@@ -44,11 +47,13 @@ _hurd_select (int nfds,
{
int i;
mach_port_t portset;
- int got;
+ int got, ready;
error_t err;
fd_set rfds, wfds, xfds;
int firstfd, lastfd;
- mach_msg_timeout_t to = 0;
+ mach_msg_id_t reply_msgid;
+ mach_msg_timeout_t to;
+ struct timespec ts;
struct
{
struct hurd_userlink ulink;
@@ -73,16 +78,39 @@ _hurd_select (int nfds,
return -1;
}
- if (timeout != NULL)
+#define IO_SELECT_REPLY_MSGID (21012 + 100) /* XXX */
+#define IO_SELECT_TIMEOUT_REPLY_MSGID (21031 + 100) /* XXX */
+
+ if (timeout == NULL)
+ reply_msgid = IO_SELECT_REPLY_MSGID;
+ else
{
- if (timeout->tv_sec < 0 || timeout->tv_nsec < 0)
+ struct timeval now;
+
+ if (timeout->tv_sec < 0 || timeout->tv_nsec < 0 ||
+ timeout->tv_nsec >= 1000000000)
{
errno = EINVAL;
return -1;
}
- to = (timeout->tv_sec * 1000 +
- (timeout->tv_nsec + 999999) / 1000000);
+ err = __gettimeofday(&now, NULL);
+ if (err)
+ return -1;
+
+ ts.tv_sec = now.tv_sec + timeout->tv_sec;
+ ts.tv_nsec = now.tv_usec * 1000 + timeout->tv_nsec;
+
+ if (ts.tv_nsec >= 1000000000)
+ {
+ ts.tv_sec++;
+ ts.tv_nsec -= 1000000000;
+ }
+
+ if (ts.tv_sec < 0)
+ ts.tv_sec = LONG_MAX; /* XXX */
+
+ reply_msgid = IO_SELECT_TIMEOUT_REPLY_MSGID;
}
if (sigmask && __sigprocmask (SIG_SETMASK, sigmask, &oset))
@@ -236,12 +264,13 @@ _hurd_select (int nfds,
{
int type = d[i].type;
d[i].reply_port = __mach_reply_port ();
- err = __io_select (d[i].io_port, d[i].reply_port, 0, &type);
- switch (err)
+ if (timeout == NULL)
+ err = __io_select_request (d[i].io_port, d[i].reply_port, type);
+ else
+ err = __io_select_timeout_request (d[i].io_port, d[i].reply_port,
+ ts, type);
+ if (!err)
{
- case MACH_RCV_TIMED_OUT:
- /* No immediate response. This is normal. */
- err = 0;
if (firstfd == lastfd)
/* When there's a single descriptor, we don't need a
portset, so just pretend we have one, but really
@@ -262,32 +291,24 @@ _hurd_select (int nfds,
__mach_port_move_member (__mach_task_self (),
d[i].reply_port, portset);
}
- break;
-
- default:
- /* No other error should happen. Callers of select
+ }
+ else
+ {
+ /* No error should happen. Callers of select
don't expect to see errors, so we simulate
readiness of the erring object and the next call
hopefully will get the error again. */
- type = SELECT_ALL;
- /* FALLTHROUGH */
-
- case 0:
- /* We got an answer. */
- if ((type & SELECT_ALL) == 0)
- /* Bogus answer; treat like an error, as a fake positive. */
- type = SELECT_ALL;
-
- /* This port is already ready already. */
- d[i].type &= type;
d[i].type |= SELECT_RETURNED;
++got;
- break;
}
_hurd_port_free (&d[i].cell->port, &d[i].ulink, d[i].io_port);
}
}
+ /* GOT is the number of replies (or errors), while READY is the number of
+ replies with at least one type bit set. */
+ ready = 0;
+
/* Now wait for reply messages. */
if (!err && got == 0)
{
@@ -329,22 +350,35 @@ _hurd_select (int nfds,
} success;
#endif
} msg;
- mach_msg_option_t options = (timeout == NULL ? 0 : MACH_RCV_TIMEOUT);
+ mach_msg_option_t options;
error_t msgerr;
+
+ /* We rely on servers to implement the timeout, but when there are none,
+ do it on the client side. */
+ if (timeout != NULL && firstfd == -1)
+ {
+ options = MACH_RCV_TIMEOUT;
+ to = timeout->tv_sec * 1000 + (timeout->tv_nsec + 999999) / 1000000;
+ }
+ else
+ {
+ options = 0;
+ to = MACH_MSG_TIMEOUT_NONE;
+ }
+
while ((msgerr = __mach_msg (&msg.head,
MACH_RCV_MSG | MACH_RCV_INTERRUPT | options,
0, sizeof msg, portset, to,
MACH_PORT_NULL)) == MACH_MSG_SUCCESS)
{
/* We got a message. Decode it. */
-#define IO_SELECT_REPLY_MSGID (21012 + 100) /* XXX */
#ifdef MACH_MSG_TYPE_BIT
const union typeword inttype =
{ type:
{ MACH_MSG_TYPE_INTEGER_T, sizeof (integer_t) * 8, 1, 1, 0, 0 }
};
#endif
- if (msg.head.msgh_id == IO_SELECT_REPLY_MSGID &&
+ if (msg.head.msgh_id == reply_msgid &&
msg.head.msgh_size >= sizeof msg.error &&
!(msg.head.msgh_bits & MACH_MSGH_BITS_COMPLEX) &&
#ifdef MACH_MSG_TYPE_BIT
@@ -362,12 +396,13 @@ _hurd_select (int nfds,
err = EINTR;
goto poll;
}
+ /* Keep in mind msg.success.result can be 0 if a timeout
+ occurred. */
if (msg.error.err ||
- msg.head.msgh_size != sizeof msg.success ||
#ifdef MACH_MSG_TYPE_BIT
msg.success.result_type.word != inttype.word ||
#endif
- (msg.success.result & SELECT_ALL) == 0)
+ msg.head.msgh_size != sizeof msg.success)
{
/* Error or bogus reply. Simulate readiness. */
__mach_msg_destroy (&msg.head);
@@ -384,6 +419,9 @@ _hurd_select (int nfds,
&& d[i].reply_port == msg.head.msgh_local_port)
{
d[i].type &= msg.success.result;
+ if (d[i].type)
+ ++ready;
+
d[i].type |= SELECT_RETURNED;
++got;
}
@@ -415,7 +453,7 @@ _hurd_select (int nfds,
/* Interruption on our side (e.g. signal reception). */
err = EINTR;
- if (got)
+ if (ready)
/* At least one descriptor is known to be ready now, so we will
return success. */
err = 0;
@@ -459,9 +497,9 @@ _hurd_select (int nfds,
}
else
{
- /* Below we recalculate GOT to include an increment for each operation
+ /* Below we recalculate READY to include an increment for each operation
allowed on each fd. */
- got = 0;
+ ready = 0;
/* Set the user bitarrays. We only ever have to clear bits, as all
desired ones are initially set. */
@@ -474,15 +512,15 @@ _hurd_select (int nfds,
type = 0;
if (type & SELECT_READ)
- got++;
+ ready++;
else if (readfds)
FD_CLR (i, readfds);
if (type & SELECT_WRITE)
- got++;
+ ready++;
else if (writefds)
FD_CLR (i, writefds);
if (type & SELECT_URG)
- got++;
+ ready++;
else if (exceptfds)
FD_CLR (i, exceptfds);
}
@@ -491,5 +529,5 @@ _hurd_select (int nfds,
if (sigmask && __sigprocmask (SIG_SETMASK, &oset, NULL))
return -1;
- return got;
+ return ready;
}
|