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ext/opcache: use pthread_mutex_t instead of a fcntl(F_SETLK) #10277

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ext/opcache: use pthread_mutex_t instead of a fcntl(F_SETLK) #10277

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12 changes: 12 additions & 0 deletions ext/opcache/config.m4
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,18 @@ if test "$PHP_OPCACHE" != "no"; then
dnl Always build as shared extension
ext_shared=yes

if test "$pthreads_working" = "yes"; then
AC_CHECK_FUNC(pthread_mutexattr_setpshared, [
AC_DEFINE(HAVE_PTHREAD_PROCESS_SHARED, 1, [Define to use pthread_mutexattr_setpshared(PTHREAD_PROCESS_SHARED)])
if test -n "$ac_cv_pthreads_lib"; then
PHP_EVAL_LIBLINE(-l$ac_cv_pthreads_lib, OPCACHE_SHARED_LIBADD)
fi
if test -n "$ac_cv_pthreads_cflags"; then
PHP_EVAL_INCLINE($ac_cv_pthreads_cflags)
fi
], [])
fi

if test "$PHP_HUGE_CODE_PAGES" = "yes"; then
AC_DEFINE(HAVE_HUGE_CODE_PAGES, 1, [Define to enable copying PHP CODE pages into HUGE PAGES (experimental)])
fi
Expand Down
72 changes: 59 additions & 13 deletions ext/opcache/zend_shared_alloc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -55,6 +55,29 @@ static const char *g_shared_model;
/* pointer to globals allocated in SHM and shared across processes */
zend_smm_shared_globals *smm_shared_globals;

#ifdef HAVE_PTHREAD_PROCESS_SHARED

#include <pthread.h>

/**
* This struct is allocated from shared memory and contains a
* PTHREAD_PROCESS_SHARED mutex.
*/
struct opcache_locks {
/**
* The mutex for zend_shared_alloc_lock().
*/
pthread_mutex_t alloc;
};

/**
* Note, this variable should not be put in struct zend_accel_globals
* because this is not a per-thread variable.
*/
static struct opcache_locks *opcache_locks;

#endif // HAVE_PTHREAD_PROCESS_SHARED

#ifndef ZEND_WIN32
#ifdef ZTS
static MUTEX_T zts_lock;
Expand Down Expand Up @@ -82,12 +105,24 @@ static const zend_shared_memory_handler_entry handler_table[] = {
#ifndef ZEND_WIN32
void zend_shared_alloc_create_lock(char *lockfile_path)
{
int val;

#ifdef ZTS
zts_lock = tsrm_mutex_alloc();
#endif

#ifdef HAVE_PTHREAD_PROCESS_SHARED
opcache_locks = mmap(NULL, sizeof(*opcache_locks),
PROT_READ|PROT_WRITE,
MAP_SHARED|MAP_ANONYMOUS, -1, 0);
if (opcache_locks == MAP_FAILED) {
zend_accel_error_noreturn(ACCEL_LOG_FATAL, "Unable to create opcache_locks: %s (%d)", strerror(errno), errno);
}

pthread_mutexattr_t mutexattr;
pthread_mutexattr_init(&mutexattr);
pthread_mutexattr_setpshared(&mutexattr, PTHREAD_PROCESS_SHARED);
pthread_mutex_init(&opcache_locks->alloc, &mutexattr);
#endif // HAVE_PTHREAD_PROCESS_SHARED

#if defined(__linux__) && defined(HAVE_MEMFD_CREATE)
/* on Linux, we can use a memfd instead of a "real" file, so
* we can do this without a writable filesystem and without
Expand All @@ -108,7 +143,7 @@ void zend_shared_alloc_create_lock(char *lockfile_path)

fchmod(lock_file, 0666);

val = fcntl(lock_file, F_GETFD, 0);
int val = fcntl(lock_file, F_GETFD, 0);
val |= FD_CLOEXEC;
fcntl(lock_file, F_SETFD, val);

Expand Down Expand Up @@ -320,6 +355,12 @@ void zend_shared_alloc_shutdown(void)
}
ZSMMG(shared_segments) = NULL;
g_shared_alloc_handler = NULL;

#ifdef HAVE_PTHREAD_PROCESS_SHARED
pthread_mutex_destroy(&opcache_locks->alloc);
munmap(opcache_locks, sizeof(opcache_locks));
#endif

#ifndef ZEND_WIN32
close(lock_file);

Expand Down Expand Up @@ -471,18 +512,20 @@ void zend_shared_alloc_lock(void)
{
ZEND_ASSERT(!ZCG(locked));

#ifndef ZEND_WIN32
#if !defined(ZEND_WIN32) && defined(ZTS)
tsrm_mutex_lock(zts_lock);
#endif

#ifdef HAVE_PTHREAD_PROCESS_SHARED
pthread_mutex_lock(&opcache_locks->alloc);
#elif !defined(ZEND_WIN32)
struct flock mem_write_lock;

mem_write_lock.l_type = F_WRLCK;
mem_write_lock.l_whence = SEEK_SET;
mem_write_lock.l_start = 0;
mem_write_lock.l_len = 1;

#ifdef ZTS
tsrm_mutex_lock(zts_lock);
#endif

#if 0
/* this will happen once per process, and will un-globalize mem_write_lock */
if (mem_write_lock.l_pid == -1) {
Expand Down Expand Up @@ -510,7 +553,7 @@ void zend_shared_alloc_unlock(void)
{
ZEND_ASSERT(ZCG(locked));

#ifndef ZEND_WIN32
#if !defined(ZEND_WIN32) && !defined(HAVE_PTHREAD_PROCESS_SHARED)
struct flock mem_write_unlock;

mem_write_unlock.l_type = F_UNLCK;
Expand All @@ -521,16 +564,19 @@ void zend_shared_alloc_unlock(void)

ZCG(locked) = 0;

#ifndef ZEND_WIN32
#ifdef HAVE_PTHREAD_PROCESS_SHARED
pthread_mutex_unlock(&opcache_locks->alloc);
#elif !defined(ZEND_WIN32)
if (fcntl(lock_file, F_SETLK, &mem_write_unlock) == -1) {
zend_accel_error_noreturn(ACCEL_LOG_ERROR, "Cannot remove lock - %s (%d)", strerror(errno), errno);
}
#ifdef ZTS
tsrm_mutex_unlock(zts_lock);
#endif
#else
zend_shared_alloc_unlock_win32();
#endif

#if !defined(ZEND_WIN32) && defined(ZTS)
tsrm_mutex_unlock(zts_lock);
#endif
}

void zend_shared_alloc_init_xlat_table(void)
Expand Down