X-Git-Url: https://git.lttng.org/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fcommon%2Fcompat%2Fcompat-poll.c;h=79756f5731fa48dd41ac2c646333c4f1080278b3;hp=7d4d0e1334ef1dc2abba28f9e694d2ce8052d1ea;hb=cc0acbd149005db7b944856be2aff499f38c0d64;hpb=c607fe035ea8821a8f4c6ab6f3467ec726e36a63 diff --git a/src/common/compat/compat-poll.c b/src/common/compat/compat-poll.c index 7d4d0e133..79756f573 100644 --- a/src/common/compat/compat-poll.c +++ b/src/common/compat/compat-poll.c @@ -1,5 +1,6 @@ /* * Copyright (C) 2011 - David Goulet + * Copyright (C) 2019 - Yannick Lamarre * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License, version 2 only, @@ -20,6 +21,7 @@ #include #include #include +#include #include #include @@ -28,7 +30,14 @@ #include "poll.h" -unsigned int poll_max_size; + +/* + * Maximum number of fd we can monitor. + * + * For poll(2), the max fds must not exceed RLIMIT_NOFILE given by + * getrlimit(2). + */ +static unsigned int poll_max_size; /* * Resize the epoll events structure of the new size. @@ -101,6 +110,7 @@ error: /* * Create pollfd data structure. */ +LTTNG_HIDDEN int compat_poll_create(struct lttng_poll_event *events, int size) { struct compat_poll_event_array *current, *wait; @@ -153,6 +163,7 @@ error: /* * Add fd to pollfd data structure with requested events. */ +LTTNG_HIDDEN int compat_poll_add(struct lttng_poll_event *events, int fd, uint32_t req_events) { @@ -196,16 +207,55 @@ error: return -1; } +/* + * Modify an fd's events.. + */ +LTTNG_HIDDEN +int compat_poll_mod(struct lttng_poll_event *events, int fd, + uint32_t req_events) +{ + int i; + struct compat_poll_event_array *current; + + if (events == NULL || events->current.nb_fd == 0 || + events->current.events == NULL || fd < 0) { + ERR("Bad compat poll mod arguments"); + goto error; + } + + current = &events->current; + + for (i = 0; i < current->nb_fd; i++) { + if (current->events[i].fd == fd) { + current->events[i].events = req_events; + events->need_update = 1; + break; + } + } + + /* + * The epoll flavor doesn't flag modifying a non-included FD as an + * error. + */ + + return 0; + +error: + return -1; +} + /* * Remove a fd from the pollfd structure. */ +LTTNG_HIDDEN int compat_poll_del(struct lttng_poll_event *events, int fd) { - int new_size, i, count = 0, ret; + int i, count = 0, ret; + uint32_t new_size; struct compat_poll_event_array *current; - if (events == NULL || events->current.events == NULL || fd < 0) { - ERR("Wrong arguments for poll del"); + if (events == NULL || events->current.nb_fd == 0 || + events->current.events == NULL || fd < 0) { goto error; } @@ -220,13 +270,20 @@ int compat_poll_del(struct lttng_poll_event *events, int fd) count++; } } + + /* The fd was not in our set, return no error as with epoll. */ + if (current->nb_fd == count) { + goto end; + } + /* No fd duplicate should be ever added into array. */ assert(current->nb_fd - 1 == count); current->nb_fd = count; /* Resize array if needed. */ new_size = 1U << utils_get_count_order_u32(current->nb_fd); - if (new_size != current->alloc_size && new_size >= current->init_size) { + if (new_size != current->alloc_size && new_size >= current->init_size + && current->nb_fd != 0) { ret = resize_poll_event(current, new_size); if (ret < 0) { goto error; @@ -235,6 +292,7 @@ int compat_poll_del(struct lttng_poll_event *events, int fd) events->need_update = 1; +end: return 0; error: @@ -244,9 +302,13 @@ error: /* * Wait on poll() with timeout. Blocking call. */ -int compat_poll_wait(struct lttng_poll_event *events, int timeout) +LTTNG_HIDDEN +int compat_poll_wait(struct lttng_poll_event *events, int timeout, + bool interruptible) { - int ret; + int ret, active_fd_count; + int idle_pfd_index = 0; + size_t i; if (events == NULL || events->current.events == NULL) { ERR("poll wait arguments error"); @@ -271,18 +333,47 @@ int compat_poll_wait(struct lttng_poll_event *events, int timeout) do { ret = poll(events->wait.events, events->wait.nb_fd, timeout); - } while (ret == -1 && errno == EINTR); + } while (!interruptible && ret == -1 && errno == EINTR); if (ret < 0) { - /* At this point, every error is fatal */ - PERROR("poll wait"); + if (errno != EINTR) { + PERROR("poll wait"); + } goto error; } + active_fd_count = ret; + /* - * poll() should always iterate on all FDs since we handle the pollset in - * user space and after poll returns, we have to try every fd for a match. + * Swap all active pollfd structs to the beginning of the + * array to emulate compat-epoll behaviour. This algorithm takes + * advantage of poll's returned value and the burst nature of active + * events on the file descriptors. The while loop guarantees that + * idle_pfd will always point to an idle fd. */ - return events->wait.nb_fd; + if (active_fd_count == events->wait.nb_fd) { + goto end; + } + while (idle_pfd_index < active_fd_count && + events->wait.events[idle_pfd_index].revents != 0) { + idle_pfd_index++; + } + + for (i = idle_pfd_index + 1; idle_pfd_index < active_fd_count; + i++) { + struct pollfd swap_pfd; + struct pollfd *idle_pfd = &events->wait.events[idle_pfd_index]; + struct pollfd *current_pfd = &events->wait.events[i]; + + if (idle_pfd->revents != 0) { + swap_pfd = *current_pfd; + *current_pfd = *idle_pfd; + *idle_pfd = swap_pfd; + idle_pfd_index++; + } + } + +end: + return ret; error: return -1; @@ -291,6 +382,7 @@ error: /* * Setup poll set maximum size. */ +LTTNG_HIDDEN int compat_poll_set_max_size(void) { int ret, retval = 0;