// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/file.c
*
* Copyright (C) 1998-1999, Stephen Tweedie and Bill Hawes
*
* Manage the dynamic fd arrays in the process files_struct.
*/
#include <linux/syscalls.h>
#include <linux/export.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/sched/signal.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/fdtable.h>
#include <linux/bitops.h>
#include <linux/spinlock.h>
#include <linux/rcupdate.h>
#include <linux/close_range.h>
#include <linux/file_ref.h>
#include <net/sock.h>
#include "internal.h"
/**
* __file_ref_put - Slowpath of file_ref_put()
* @ref: Pointer to the reference count
* @cnt: Current reference count
*
* Invoked when the reference count is outside of the valid zone.
*
* Return:
* True if this was the last reference with no future references
* possible. This signals the caller that it can safely schedule the
* object, which is protected by the reference counter, for
* deconstruction.
*
* False if there are still active references or the put() raced
* with a concurrent get()/put() pair. Caller is not allowed to
* deconstruct the protected object.
*/
bool __file_ref_put(file_ref_t *ref, unsigned long cnt)
{
/* Did this drop the last reference? */
if (likely(cnt == FILE_REF_NOREF)) {
/*
* Carefully try to set the reference count to FILE_REF_DEAD.
*
* This can fail if a concurrent get() operation has
* elevated it again or the corresponding put() even marked
* it dead already. Both are valid situations and do not
* require a retry. If this fails the caller is not
* allowed to deconstruct the object.
*/
if (!atomic_long_try_cmpxchg_release(&ref->refcnt, &cnt, FILE_REF_DEAD))
return false;
/*
* The caller can safely schedule the object for
* deconstruction. Provide acquire ordering.
*/
smp_acquire__after_ctrl_dep();
return true;
}
/*
* If the reference count was already in the dead zone, then this
* put() operation is imbalanced. Warn