Server : nginx/1.18.0 System : Linux localhost 6.14.3-x86_64-linode168 #1 SMP PREEMPT_DYNAMIC Mon Apr 21 19:47:55 EDT 2025 x86_64 User : www-data ( 33) PHP Version : 8.0.16 Disable Function : pcntl_alarm,pcntl_fork,pcntl_waitpid,pcntl_wait,pcntl_wifexited,pcntl_wifstopped,pcntl_wifsignaled,pcntl_wifcontinued,pcntl_wexitstatus,pcntl_wtermsig,pcntl_wstopsig,pcntl_signal,pcntl_signal_get_handler,pcntl_signal_dispatch,pcntl_get_last_error,pcntl_strerror,pcntl_sigprocmask,pcntl_sigwaitinfo,pcntl_sigtimedwait,pcntl_exec,pcntl_getpriority,pcntl_setpriority,pcntl_async_signals,pcntl_unshare, Directory :  /usr/src/linux-headers-5.4.0-216/include/vdso/

Upload File : current_dir [ Writeable ] document_root [ Writeable ]

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __VDSO_HELPERS_H
#define __VDSO_HELPERS_H

#ifndef __ASSEMBLY__

#include <vdso/datapage.h>

static __always_inline u32 vdso_read_begin(const struct vdso_data *vd)
{
	u32 seq;

	while ((seq = READ_ONCE(vd->seq)) & 1)
		cpu_relax();

	smp_rmb();
	return seq;
}

static __always_inline u32 vdso_read_retry(const struct vdso_data *vd,
					   u32 start)
{
	u32 seq;

	smp_rmb();
	seq = READ_ONCE(vd->seq);
	return seq != start;
}

static __always_inline void vdso_write_begin(struct vdso_data *vd)
{
	/*
	 * WRITE_ONCE it is required otherwise the compiler can validly tear
	 * updates to vd[x].seq and it is possible that the value seen by the
	 * reader it is inconsistent.
	 */
	WRITE_ONCE(vd[CS_HRES_COARSE].seq, vd[CS_HRES_COARSE].seq + 1);
	WRITE_ONCE(vd[CS_RAW].seq, vd[CS_RAW].seq + 1);
	smp_wmb();
}

static __always_inline void vdso_write_end(struct vdso_data *vd)
{
	smp_wmb();
	/*
	 * WRITE_ONCE it is required otherwise the compiler can validly tear
	 * updates to vd[x].seq and it is possible that the value seen by the
	 * reader it is inconsistent.
	 */
	WRITE_ONCE(vd[CS_HRES_COARSE].seq, vd[CS_HRES_COARSE].seq + 1);
	WRITE_ONCE(vd[CS_RAW].seq, vd[CS_RAW].seq + 1);
}

#endif /* !__ASSEMBLY__ */

#endif /* __VDSO_HELPERS_H */