src/bin/lttng-sessiond/compat/poll.h

   1 /*
   2  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License as published by the Free
   6  * Software Foundation; only version 2 of the License.
   7  *
   8  * This program is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
  15  * Place - Suite 330, Boston, MA  02111-1307, USA.
  16  */
  17
  18 #ifndef _LTT_POLL_H
  19 #define _LTT_POLL_H
  20
  21 #include <string.h>
  22 #include <unistd.h>
  23
  24 #include <common/lttng-share.h>
  25
  26 /*
  27  * Value taken from the hard limit allowed by the kernel when using setrlimit
  28  * with RLIMIT_NOFILE on an Intel i7 CPU and Linux 3.0.3.
  29  */
  30 #define LTTNG_POLL_DEFAULT_SIZE 65535
  31
  32 /*
  33  * Maximum number of fd we can monitor.
  34  *
  35  * For epoll(7), /proc/sys/fs/epoll/max_user_watches (since Linux 2.6.28) will
  36  * be used for the maximum size of the poll set. If this interface is not
  37  * available, according to the manpage, the max_user_watches value is 1/25 (4%)
  38  * of the available low memory divided by the registration cost in bytes which
  39  * is 90 bytes on a 32-bit kernel and 160 bytes on a 64-bit kernel.
  40  *
  41  * For poll(2), the max fds must not exceed RLIMIT_NOFILE given by
  42  * getrlimit(2).
  43  */
  44 extern unsigned int poll_max_size;
  45
  46 /*
  47  * Used by lttng_poll_clean to free the events structure in a lttng_poll_event.
  48  */
  49 static inline void __lttng_poll_free(void *events)
  50 {
  51         free(events);
  52 }
  53
  54 /*
  55  * epoll(7) implementation.
  56  */
  57 #ifdef HAVE_EPOLL
  58 #include <sys/epoll.h>
  59
  60 /* See man epoll(7) for this define path */
  61 #define LTTNG_EPOLL_PROC_PATH "/proc/sys/fs/epoll/max_user_watches"
  62
  63 enum {
  64         /* Polling variables compatibility for epoll */
  65         LPOLLIN = EPOLLIN,
  66         LPOLLPRI = EPOLLPRI,
  67         LPOLLOUT = EPOLLOUT,
  68         LPOLLRDNORM = EPOLLRDNORM,
  69         LPOLLRDBAND = EPOLLRDBAND,
  70         LPOLLWRNORM = EPOLLWRNORM,
  71         LPOLLWRBAND = EPOLLWRBAND,
  72         LPOLLMSG = EPOLLMSG,
  73         LPOLLERR = EPOLLERR,
  74         LPOLLHUP = EPOLLHUP,
  75         LPOLLNVAL = EPOLLHUP,
  76         LPOLLRDHUP = EPOLLRDHUP,
  77         /* Close on exec feature of epoll */
  78         LTTNG_CLOEXEC = EPOLL_CLOEXEC,
  79 };
  80
  81 struct compat_epoll_event {
  82         int epfd;
  83         uint32_t nb_fd;       /* Current number of fd in events */
  84         uint32_t events_size; /* Size of events array */
  85         struct epoll_event *events;
  86 };
  87 #define lttng_poll_event compat_epoll_event
  88
  89 /*
  90  * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
  91  * being the index of the events array.
  92  */
  93 #define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->events[i].data.fd
  94 #define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->events[i].events
  95 #define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->nb_fd
  96 #define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->events_size
  97
  98 /*
  99  * Create the epoll set. No memory allocation is done here.
 100  */
 101 extern int compat_epoll_create(struct lttng_poll_event *events,
 102                 int size, int flags);
 103 #define lttng_poll_create(events, size, flags) \
 104         compat_epoll_create(events, size, flags);
 105
 106 /*
 107  * Wait on epoll set with the number of fd registered to the lttng_poll_event
 108  * data structure (events).
 109  */
 110 extern int compat_epoll_wait(struct lttng_poll_event *events, int timeout);
 111 #define lttng_poll_wait(events, timeout) \
 112         compat_epoll_wait(events, timeout);
 113
 114 /*
 115  * Add a fd to the epoll set and resize the epoll_event structure if needed.
 116  */
 117 extern int compat_epoll_add(struct lttng_poll_event *events,
 118                 int fd, uint32_t req_events);
 119 #define lttng_poll_add(events, fd, req_events) \
 120         compat_epoll_add(events, fd, req_events);
 121
 122 /*
 123  * Remove a fd from the epoll set.
 124  */
 125 extern int compat_epoll_del(struct lttng_poll_event *events, int fd);
 126 #define lttng_poll_del(events, fd) \
 127         compat_epoll_del(events, fd);
 128
 129 /*
 130  * Set up the poll set limits variable poll_max_size
 131  */
 132 extern void compat_epoll_set_max_size(void);
 133 #define lttng_poll_set_max_size(void) \
 134         compat_epoll_set_max_size(void);
 135
 136 /*
 137  * This function memset with zero the structure since it can be reused at each
 138  * round of a main loop. Being in a loop and using a non static number of fds,
 139  * this function must be called to insure coherent events with associted fds.
 140  */
 141 static inline void lttng_poll_reset(struct lttng_poll_event *events)
 142 {
 143         if (events && events->events) {
 144                 memset(events->events, 0,
 145                                 events->nb_fd * sizeof(struct epoll_event));
 146         }
 147 }
 148
 149 /*
 150  * Clean the events structure of a lttng_poll_event. It's the caller
 151  * responsability to free the lttng_poll_event memory.
 152  */
 153 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 154 {
 155         if (events) {
 156                 close(events->epfd);
 157                 __lttng_poll_free((void *) events->events);
 158         }
 159 }
 160
 161 #else   /* HAVE_EPOLL */
 162 /*
 163  * Fallback on poll(2) API
 164  */
 165
 166 /* Needed for some poll event values */
 167 #ifndef __USE_XOPEN
 168 #define __USE_XOPEN
 169 #endif
 170
 171 /* Needed for some poll event values */
 172 #ifndef __USE_GNU
 173 #define __USE_GNU
 174 #endif
 175
 176 #include <poll.h>
 177 #include <stdint.h>
 178
 179 enum {
 180         /* Polling variables compatibility for poll */
 181         LPOLLIN = POLLIN,
 182         LPOLLPRI = POLLPRI,
 183         LPOLLOUT = POLLOUT,
 184         LPOLLRDNORM = POLLRDNORM,
 185         LPOLLRDBAND = POLLRDBAND,
 186         LPOLLWRNORM = POLLWRNORM,
 187         LPOLLWRBAND = POLLWRBAND,
 188         LPOLLMSG = POLLMSG,
 189         LPOLLERR = POLLERR,
 190         LPOLLHUP = POLLHUP | POLLNVAL,
 191         LPOLLRDHUP = POLLRDHUP,
 192         /* Close on exec feature does not exist for poll(2) */
 193         LTTNG_CLOEXEC = 0xdead,
 194 };
 195
 196 struct compat_poll_event {
 197         uint32_t nb_fd;       /* Current number of fd in events */
 198         uint32_t events_size; /* Size of events array */
 199         struct pollfd *events;
 200 };
 201 #define lttng_poll_event compat_poll_event
 202
 203 /*
 204  * For the following calls, consider 'e' to be a lttng_poll_event pointer and i
 205  * being the index of the events array.
 206  */
 207 #define LTTNG_POLL_GETFD(e, i) LTTNG_REF(e)->events[i].fd
 208 #define LTTNG_POLL_GETEV(e, i) LTTNG_REF(e)->events[i].revents
 209 #define LTTNG_POLL_GETNB(e) LTTNG_REF(e)->nb_fd
 210 #define LTTNG_POLL_GETSZ(e) LTTNG_REF(e)->events_size
 211
 212 /*
 213  * Create a pollfd structure of size 'size'.
 214  */
 215 extern int compat_poll_create(struct lttng_poll_event *events, int size);
 216 #define lttng_poll_create(events, size, flags) \
 217         compat_poll_create(events, size);
 218
 219 /*
 220  * Wait on poll(2) event with nb_fd registered to the lttng_poll_event data
 221  * structure.
 222  */
 223 extern int compat_poll_wait(struct lttng_poll_event *events, int timeout);
 224 #define lttng_poll_wait(events, timeout) \
 225         compat_poll_wait(events, timeout);
 226
 227 /*
 228  * Add the fd to the pollfd structure. Resize if needed.
 229  */
 230 extern int compat_poll_add(struct lttng_poll_event *events,
 231                 int fd, uint32_t req_events);
 232 #define lttng_poll_add(events, fd, req_events) \
 233         compat_poll_add(events, fd, req_events);
 234
 235 /*
 236  * Remove the fd from the pollfd. Memory allocation is done to recreate a new
 237  * pollfd, data is copied from the old pollfd to the new and, finally, the old
 238  * one is freed().
 239  */
 240 extern int compat_poll_del(struct lttng_poll_event *events, int fd);
 241 #define lttng_poll_del(events, fd) \
 242         compat_poll_del(events, fd);
 243
 244 /*
 245  * Set up the poll set limits variable poll_max_size
 246  */
 247 extern void compat_poll_set_max_size(void);
 248 #define lttng_poll_set_max_size(void) \
 249         compat_poll_set_max_size(void);
 250
 251 /*
 252  * No need to reset a pollfd structure for poll(2)
 253  */
 254 static inline void lttng_poll_reset(struct lttng_poll_event *events)
 255 {}
 256
 257 /*
 258  * Clean the events structure of a lttng_poll_event. It's the caller
 259  * responsability to free the lttng_poll_event memory.
 260  */
 261 static inline void lttng_poll_clean(struct lttng_poll_event *events)
 262 {
 263         if (events) {
 264                 __lttng_poll_free((void *) events->events);
 265         }
 266 }
 267
 268 #endif /* HAVE_EPOLL */
 269
 270 #endif /* _LTT_POLL_H */