RWSpinLock Class Reference

Read/write spin lock. More...

#include <md_lock.h>

List of all members.

Public Member Functions
void	ReadLock ()
	Acquire read lock.
void	ReadUnlock ()
	Release read lock.
void	WriteLock ()
	Acquire write lock.
void	WriteUnlock ()
	Release write lock.

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Detailed Description

Read/write spin lock.

It allows several simultaneous reads but doesn't allow write simultaneously with another read or write.

Several fields are defined:

• Pending write (PWR) - this flag indicates that write lock is pending. The flag can be set only if there are no WR flag set.
• Write locked (WR) - this flag indicates that write lock is currently acquired. It can be set only if RD field is zero and PWR is set. PWR is cleared when write lock is acquired.
• Read lock (RD) - field which is a counter either of currently acquired read locks (if WR is not set) or currently pending read locks (if WR is set). This field can be incremented only if PWR is not set.

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Member Function Documentation

void RWSpinLock::ReadLock

(

)

[inline]

Acquire read lock.

Several simultaneous read locks can be acquired.

void RWSpinLock::ReadUnlock

(

)

[inline]

Release read lock.

void RWSpinLock::WriteLock

(

)

[inline]

Acquire write lock.

It can be acquired only exclusively. It will not be acquired after previous write lock released and there are pending read locks.

void RWSpinLock::WriteUnlock

(

)

[inline]

Release write lock.

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The documentation for this class was generated from the following file:

• kernel/sys/arch/x86_64/md_lock.h