view src/core/ngx_rwlock.c @ 7941:65946a191197

SSL: SSL_sendfile() support with kernel TLS. Requires OpenSSL 3.0 compiled with "enable-ktls" option. Further, KTLS needs to be enabled in kernel, and in OpenSSL, either via OpenSSL configuration file or with "ssl_conf_command Options KTLS;" in nginx configuration. On FreeBSD, kernel TLS is available starting with FreeBSD 13.0, and can be enabled with "sysctl kern.ipc.tls.enable=1" and "kldload ktls_ocf" to load a software backend, see man ktls(4) for details. On Linux, kernel TLS is available starting with kernel 4.13 (at least 5.2 is recommended), and needs kernel compiled with CONFIG_TLS=y (with CONFIG_TLS=m, which is used at least on Ubuntu 21.04 by default, the tls module needs to be loaded with "modprobe tls").
author Maxim Dounin <mdounin@mdounin.ru>
date Thu, 21 Oct 2021 18:44:07 +0300
parents d1816a2696de
children 7752d8523066
line wrap: on
line source


/*
 * Copyright (C) Ruslan Ermilov
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>


#if (NGX_HAVE_ATOMIC_OPS)


#define NGX_RWLOCK_SPIN   2048
#define NGX_RWLOCK_WLOCK  ((ngx_atomic_uint_t) -1)


void
ngx_rwlock_wlock(ngx_atomic_t *lock)
{
    ngx_uint_t  i, n;

    for ( ;; ) {

        if (*lock == 0 && ngx_atomic_cmp_set(lock, 0, NGX_RWLOCK_WLOCK)) {
            return;
        }

        if (ngx_ncpu > 1) {

            for (n = 1; n < NGX_RWLOCK_SPIN; n <<= 1) {

                for (i = 0; i < n; i++) {
                    ngx_cpu_pause();
                }

                if (*lock == 0
                    && ngx_atomic_cmp_set(lock, 0, NGX_RWLOCK_WLOCK))
                {
                    return;
                }
            }
        }

        ngx_sched_yield();
    }
}


void
ngx_rwlock_rlock(ngx_atomic_t *lock)
{
    ngx_uint_t         i, n;
    ngx_atomic_uint_t  readers;

    for ( ;; ) {
        readers = *lock;

        if (readers != NGX_RWLOCK_WLOCK
            && ngx_atomic_cmp_set(lock, readers, readers + 1))
        {
            return;
        }

        if (ngx_ncpu > 1) {

            for (n = 1; n < NGX_RWLOCK_SPIN; n <<= 1) {

                for (i = 0; i < n; i++) {
                    ngx_cpu_pause();
                }

                readers = *lock;

                if (readers != NGX_RWLOCK_WLOCK
                    && ngx_atomic_cmp_set(lock, readers, readers + 1))
                {
                    return;
                }
            }
        }

        ngx_sched_yield();
    }
}


void
ngx_rwlock_unlock(ngx_atomic_t *lock)
{
    ngx_atomic_uint_t  readers;

    readers = *lock;

    if (readers == NGX_RWLOCK_WLOCK) {
        (void) ngx_atomic_cmp_set(lock, NGX_RWLOCK_WLOCK, 0);
        return;
    }

    for ( ;; ) {

        if (ngx_atomic_cmp_set(lock, readers, readers - 1)) {
            return;
        }

        readers = *lock;
    }
}


void
ngx_rwlock_downgrade(ngx_atomic_t *lock)
{
    if (*lock == NGX_RWLOCK_WLOCK) {
        *lock = 1;
    }
}


#else

#if (NGX_HTTP_UPSTREAM_ZONE || NGX_STREAM_UPSTREAM_ZONE)

#error ngx_atomic_cmp_set() is not defined!

#endif

#endif