Current File : //usr/share/systemtap/tapset/linux/atomic.stp
// Atomic functions.
// Copyright (C) 2010 Red Hat Inc.
//
// This file is part of systemtap, and is free software. You can
// redistribute it and/or modify it under the terms of the GNU General
// Public License (GPL); either version 2, or (at your option) any
// later version.
/**
* sfunction atomic_read - Retrieves an atomic variable from kernel memory
*
* @addr: pointer to atomic variable
*
* Safely perform the read of an atomic variable.
*/
function atomic_read:long(addr:long)
%{ /* pure */
atomic_t *a = (atomic_t *)(uintptr_t)STAP_ARG_addr;
/* We call deref() here to ensure the memory is valid to read.
* Note the result is thrown away, then we use the "real"
* atomic read function now that we know the address is safe. */
(void)kderef(sizeof(*a), a);
STAP_RETVALUE = atomic_read(a);
CATCH_DEREF_FAULT();
%}
/**
* sfunction atomic_long_read - Retrieves an atomic long variable from kernel memory
*
* @addr: pointer to atomic long variable
*
* Safely perform the read of an atomic long variable. This will be a
* NOP on kernels that do not have ATOMIC_LONG_INIT set on the kernel config.
*/
function atomic_long_read:long(addr:long)
%{ /* pure */
#ifdef ATOMIC_LONG_INIT
atomic_long_t *a = (atomic_long_t *)(uintptr_t)STAP_ARG_addr;
/* We call deref() here to ensure the memory is valid to read.
* Note the result is thrown away, then we use the "real"
* atomic read function now that we know the address is safe. */
(void)kderef(sizeof(*a), a);
STAP_RETVALUE = atomic_long_read(a);
CATCH_DEREF_FAULT();
#endif
%}
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