nginx 0.6.27 *) Change: now by default the rtsig method is not built on Linux 2.6.18+. *) Change: now a request method is not changed while redirection to a named location via an "error_page" directive. *) Feature: the "resolver" and "resolver_timeout" directives in SMTP proxy. *) Feature: the "post_action" directive supports named locations. *) Bugfix: a segmentation fault occurred in worker process, if a request was redirected from proxy, FastCGI, or memcached location to static named locations. *) Bugfix: browsers did not repeat SSL handshake if there is no valid client certificate in first handshake. Thanks to Alexander V. Inyukhin. *) Bugfix: if response code 495-497 was redirected via an "error_page" directive without code change, then nginx tried to allocate too many memory. *) Bugfix: memory leak in long-lived non buffered connections. *) Bugfix: memory leak in resolver. *) Bugfix: a segmentation fault occurred in worker process, if a request was redirected from proxy, FastCGI, or memcached location to static named locations. *) Bugfix: in the $proxy_host and $proxy_port variables caching. Thanks to Sergey Bochenkov. *) Bugfix: a "proxy_pass" directive with variables used incorrectly the same port as in another "proxy_pass" directive with the same host name and without variables. Thanks to Sergey Bochenkov. *) Bugfix: an alert "sendmsg() failed (9: Bad file descriptor)" on some 64-bit platforms while reconfiguration. *) Bugfix: a segmentation fault occurred in worker process, if empty stub block was used second time in SSI. *) Bugfix: in copying URI part contained escaped symbols into arguments.

/*
 * 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")