Mercurial > hg > nginx
view src/core/ngx_shmtx.c @ 5742:c45c9812cf11
Core: removed meaningless check from ngx_palloc_block().
The check became meaningless after refactoring in 2a92804f4109.
With the loop currently in place, "current" can't be NULL, hence
the check can be dropped.
Additionally, the local variable "current" was removed to
simplify code, and pool->current now used directly instead.
Found by Coverity (CID 714236).
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Thu, 26 Jun 2014 03:34:19 +0400 |
parents | 0fce5bb53b2d |
children | 74edc0ccf27a |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #if (NGX_HAVE_ATOMIC_OPS) static void ngx_shmtx_wakeup(ngx_shmtx_t *mtx); ngx_int_t ngx_shmtx_create(ngx_shmtx_t *mtx, ngx_shmtx_sh_t *addr, u_char *name) { mtx->lock = &addr->lock; if (mtx->spin == (ngx_uint_t) -1) { return NGX_OK; } mtx->spin = 2048; #if (NGX_HAVE_POSIX_SEM) mtx->wait = &addr->wait; if (sem_init(&mtx->sem, 1, 0) == -1) { ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_errno, "sem_init() failed"); } else { mtx->semaphore = 1; } #endif return NGX_OK; } void ngx_shmtx_destroy(ngx_shmtx_t *mtx) { #if (NGX_HAVE_POSIX_SEM) if (mtx->semaphore) { if (sem_destroy(&mtx->sem) == -1) { ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_errno, "sem_destroy() failed"); } } #endif } ngx_uint_t ngx_shmtx_trylock(ngx_shmtx_t *mtx) { return (*mtx->lock == 0 && ngx_atomic_cmp_set(mtx->lock, 0, ngx_pid)); } void ngx_shmtx_lock(ngx_shmtx_t *mtx) { ngx_uint_t i, n; ngx_log_debug0(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0, "shmtx lock"); for ( ;; ) { if (*mtx->lock == 0 && ngx_atomic_cmp_set(mtx->lock, 0, ngx_pid)) { return; } if (ngx_ncpu > 1) { for (n = 1; n < mtx->spin; n <<= 1) { for (i = 0; i < n; i++) { ngx_cpu_pause(); } if (*mtx->lock == 0 && ngx_atomic_cmp_set(mtx->lock, 0, ngx_pid)) { return; } } } #if (NGX_HAVE_POSIX_SEM) if (mtx->semaphore) { (void) ngx_atomic_fetch_add(mtx->wait, 1); if (*mtx->lock == 0 && ngx_atomic_cmp_set(mtx->lock, 0, ngx_pid)) { return; } ngx_log_debug1(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0, "shmtx wait %uA", *mtx->wait); while (sem_wait(&mtx->sem) == -1) { ngx_err_t err; err = ngx_errno; if (err != NGX_EINTR) { ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, err, "sem_wait() failed while waiting on shmtx"); break; } } ngx_log_debug0(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0, "shmtx awoke"); continue; } #endif ngx_sched_yield(); } } void ngx_shmtx_unlock(ngx_shmtx_t *mtx) { if (mtx->spin != (ngx_uint_t) -1) { ngx_log_debug0(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0, "shmtx unlock"); } if (ngx_atomic_cmp_set(mtx->lock, ngx_pid, 0)) { ngx_shmtx_wakeup(mtx); } } ngx_uint_t ngx_shmtx_force_unlock(ngx_shmtx_t *mtx, ngx_pid_t pid) { ngx_log_debug0(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0, "shmtx forced unlock"); if (ngx_atomic_cmp_set(mtx->lock, pid, 0)) { ngx_shmtx_wakeup(mtx); return 1; } return 0; } static void ngx_shmtx_wakeup(ngx_shmtx_t *mtx) { #if (NGX_HAVE_POSIX_SEM) ngx_atomic_uint_t wait; if (!mtx->semaphore) { return; } for ( ;; ) { wait = *mtx->wait; if (wait == 0) { return; } if (ngx_atomic_cmp_set(mtx->wait, wait, wait - 1)) { break; } } ngx_log_debug1(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0, "shmtx wake %uA", wait); if (sem_post(&mtx->sem) == -1) { ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_errno, "sem_post() failed while wake shmtx"); } #endif } #else ngx_int_t ngx_shmtx_create(ngx_shmtx_t *mtx, ngx_shmtx_sh_t *addr, u_char *name) { if (mtx->name) { if (ngx_strcmp(name, mtx->name) == 0) { mtx->name = name; return NGX_OK; } ngx_shmtx_destroy(mtx); } mtx->fd = ngx_open_file(name, NGX_FILE_RDWR, NGX_FILE_CREATE_OR_OPEN, NGX_FILE_DEFAULT_ACCESS); if (mtx->fd == NGX_INVALID_FILE) { ngx_log_error(NGX_LOG_EMERG, ngx_cycle->log, ngx_errno, ngx_open_file_n " \"%s\" failed", name); return NGX_ERROR; } if (ngx_delete_file(name) == NGX_FILE_ERROR) { ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_errno, ngx_delete_file_n " \"%s\" failed", name); } mtx->name = name; return NGX_OK; } void ngx_shmtx_destroy(ngx_shmtx_t *mtx) { if (ngx_close_file(mtx->fd) == NGX_FILE_ERROR) { ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_errno, ngx_close_file_n " \"%s\" failed", mtx->name); } } ngx_uint_t ngx_shmtx_trylock(ngx_shmtx_t *mtx) { ngx_err_t err; err = ngx_trylock_fd(mtx->fd); if (err == 0) { return 1; } if (err == NGX_EAGAIN) { return 0; } #if __osf__ /* Tru64 UNIX */ if (err == NGX_EACCESS) { return 0; } #endif ngx_log_abort(err, ngx_trylock_fd_n " %s failed", mtx->name); return 0; } void ngx_shmtx_lock(ngx_shmtx_t *mtx) { ngx_err_t err; err = ngx_lock_fd(mtx->fd); if (err == 0) { return; } ngx_log_abort(err, ngx_lock_fd_n " %s failed", mtx->name); } void ngx_shmtx_unlock(ngx_shmtx_t *mtx) { ngx_err_t err; err = ngx_unlock_fd(mtx->fd); if (err == 0) { return; } ngx_log_abort(err, ngx_unlock_fd_n " %s failed", mtx->name); } ngx_uint_t ngx_shmtx_force_unlock(ngx_shmtx_t *mtx, ngx_pid_t pid) { return 0; } #endif