<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> <HTML ><HEAD ><TITLE >Locking Between Tasklets</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK REL="HOME" TITLE="Unreliable Guide To Locking" HREF="book1.html"><LINK REL="UP" TITLE="Two Main Types of Kernel Locks: Spinlocks and Semaphores" HREF="c88.html"><LINK REL="PREVIOUS" TITLE="Locking Between Bottom Halves" HREF="x144.html"><LINK REL="NEXT" TITLE="Locking Between Softirqs" HREF="x165.html"></HEAD ><BODY CLASS="SECT1" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >Unreliable Guide To Locking</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="x144.html" ACCESSKEY="P" ><<< Previous</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" >Two Main Types of Kernel Locks: Spinlocks and Semaphores</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="x165.html" ACCESSKEY="N" >Next >>></A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="LOCK-TASKLETS" ></A >Locking Between Tasklets</H1 ><P > Sometimes a tasklet might want to share data with another tasklet, or a bottom half. </P ><DIV CLASS="SECT2" ><H2 CLASS="SECT2" ><A NAME="LOCK-TASKLETS-SAME" ></A >The Same Tasklet</H2 ><P > Since a tasklet is never run on two CPUs at once, you don't need to worry about your tasklet being reentrant (running twice at once), even on SMP. </P ></DIV ><DIV CLASS="SECT2" ><H2 CLASS="SECT2" ><A NAME="LOCK-TASKLETS-DIFFERENT" ></A >Different Tasklets</H2 ><P > If another tasklet (or bottom half, such as a timer) wants to share data with your tasklet, you will both need to use <TT CLASS="FUNCTION" >spin_lock()</TT > and <TT CLASS="FUNCTION" >spin_unlock()</TT > calls. <TT CLASS="FUNCTION" >spin_lock_bh()</TT > is unnecessary here, as you are already in a tasklet, and none will be run on the same CPU. </P ></DIV ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="x144.html" ACCESSKEY="P" ><<< Previous</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="book1.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="x165.html" ACCESSKEY="N" >Next >>></A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Locking Between Bottom Halves</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="c88.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Locking Between Softirqs</TD ></TR ></TABLE ></DIV ></BODY ></HTML >