nginx 0.6.7 *) Change: now the paths specified in the "include", "auth_basic_user_file", "perl_modules", "ssl_certificate", "ssl_certificate_key", and "ssl_client_certificate" directives are relative to directory of nginx configuration file nginx.conf, but not to nginx prefix directory. *) Change: the --sysconfdir=PATH option in configure was canceled. *) Change: the special make target "upgrade1" was defined for online upgrade of 0.1.x versions. *) Feature: the "server_name" and "valid_referers" directives support regular expressions. *) Feature: the "server" directive in the "upstream" context supports the "backup" parameter. *) Feature: the ngx_http_perl_module supports the $r->discard_request_body. *) Feature: the "add_header Last-Modified ..." directive changes the "Last-Modified" response header line. *) Bugfix: if an response different than 200 was returned to an request with body and connection went to the keep-alive state after the request, then nginx returned 400 for the next request. *) Bugfix: a segmentation fault occurred in worker process if invalid address was set in the "auth_http" directive. *) Bugfix: now nginx uses default listen backlog value 511 on all platforms except FreeBSD. Thanks to Jiang Hong. *) Bugfix: a worker process may got caught in an endless loop, if an "server" inside "upstream" block was marked as "down"; bug appeared in 0.6.6. *) Bugfix: now Solaris sendfilev() is not used to transfer the client request body to FastCGI-server via the unix domain socket.

/*
 * Copyright (C) Igor Sysoev
 */


#if (NGX_SMP)
#define NGX_SMP_LOCK  "lock;"
#else
#define NGX_SMP_LOCK
#endif


/*
 * "cmpxchgq  r, [m]":
 *
 *     if (rax == [m]) {
 *         zf = 1;
 *         [m] = r;
 *     } else {
 *         zf = 0;
 *         rax = [m];
 *     }
 *
 *
 * The "r" is any register, %rax (%r0) - %r16.
 * The "=a" and "a" are the %rax register.
 * Although we can return result in any register, we use "a" because it is
 * used in cmpxchgq anyway.  The result is actually in %al but not in $rax,
 * however as the code is inlined gcc can test %al as well as %rax.
 *
 * The "cc" means that flags were changed.
 */

static ngx_inline ngx_atomic_uint_t
ngx_atomic_cmp_set(ngx_atomic_t *lock, ngx_atomic_uint_t old,
    ngx_atomic_uint_t set)
{
    u_char  res;

    __asm__ volatile (

         NGX_SMP_LOCK
    "    cmpxchgq  %3, %1;   "
    "    sete      %0;       "

    : "=a" (res) : "m" (*lock), "a" (old), "r" (set) : "cc", "memory");

    return res;
}


/*
 * "xaddq  r, [m]":
 *
 *     temp = [m];
 *     [m] += r;
 *     r = temp;
 *
 *
 * The "+r" is any register, %rax (%r0) - %r16.
 * The "cc" means that flags were changed.
 */

static ngx_inline ngx_atomic_int_t
ngx_atomic_fetch_add(ngx_atomic_t *value, ngx_atomic_int_t add)
{
    __asm__ volatile (

         NGX_SMP_LOCK
    "    xaddq  %0, %1;   "

    : "+r" (add) : "m" (*value) : "cc", "memory");

    return add;
}


#define ngx_memory_barrier()    __asm__ volatile ("" ::: "memory")

#define ngx_cpu_pause()         __asm__ ("pause")