<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> <HTML ><HEAD ><TITLE >Things Which Sleep</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="Common Techniques" HREF="c196.html"><LINK REL="PREVIOUS" TITLE="Protecting A Collection of Objects: Reference Counts" HREF="x298.html"><LINK REL="NEXT" TITLE="The Fucked Up Sparc" HREF="x348.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="x298.html" ACCESSKEY="P" ><<< Previous</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" >Common Techniques</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="x348.html" ACCESSKEY="N" >Next >>></A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="SLEEPING-THINGS" ></A >Things Which Sleep</H1 ><P > You can never call the following routines while holding a spinlock, as they may sleep. This also means you need to be in user context. </P ><P ></P ><UL ><LI ><P > Accesses to <A HREF="g388.html#GLOSS-USERSPACE" ><I CLASS="FIRSTTERM" >userspace</I ></A >: </P ><P ></P ><UL ><LI ><P > <TT CLASS="FUNCTION" >copy_from_user()</TT > </P ></LI ><LI ><P > <TT CLASS="FUNCTION" >copy_to_user()</TT > </P ></LI ><LI ><P > <TT CLASS="FUNCTION" >get_user()</TT > </P ></LI ><LI ><P > <TT CLASS="FUNCTION" > put_user()</TT > </P ></LI ></UL ></LI ><LI ><P > <TT CLASS="FUNCTION" >kmalloc(GFP_KERNEL)</TT > </P ></LI ><LI ><P > <TT CLASS="FUNCTION" >down_interruptible()</TT > and <TT CLASS="FUNCTION" >down()</TT > </P ><P > There is a <TT CLASS="FUNCTION" >down_trylock()</TT > which can be used inside interrupt context, as it will not sleep. <TT CLASS="FUNCTION" >up()</TT > will also never sleep. </P ></LI ></UL ><P > <TT CLASS="FUNCTION" >printk()</TT > can be called in <I CLASS="EMPHASIS" >any</I > context, interestingly enough. </P ></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="x298.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="x348.html" ACCESSKEY="N" >Next >>></A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Protecting A Collection of Objects: Reference Counts</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="c196.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >The Fucked Up Sparc</TD ></TR ></TABLE ></DIV ></BODY ></HTML >