On Fri, May 05, 2006 at 04:40:00PM -0700, Arun Srinivasan wrote: > 235 <http://lxr.linux.no/source/include/linux/kernel.h?a=arm#L235> */*** > 236 <http://lxr.linux.no/source/include/linux/kernel.h?a=arm#L236> * * > container_of - cast a member of a structure out to the containing > structure* > 237 <http://lxr.linux.no/source/include/linux/kernel.h?a=arm#L237> * ** > 238 <http://lxr.linux.no/source/include/linux/kernel.h?a=arm#L238> * * > @ptr: the pointer to the member.* > 239 <http://lxr.linux.no/source/include/linux/kernel.h?a=arm#L239> * * > @type: the type of the container struct this is embedded in.* > 240 <http://lxr.linux.no/source/include/linux/kernel.h?a=arm#L240> * * > @member: the name of the member within the struct.* > 241 <http://lxr.linux.no/source/include/linux/kernel.h?a=arm#L241> * ** > 242 <http://lxr.linux.no/source/include/linux/kernel.h?a=arm#L242> * */* > 243 <http://lxr.linux.no/source/include/linux/kernel.h?a=arm#L243> > #define container_of > <http://lxr.linux.no/ident?a=arm;i=container_of>(ptr > <http://lxr.linux.no/ident?a=arm;i=ptr>, type > <http://lxr.linux.no/ident?a=arm;i=type>, member) ({ > \ > 244 <http://lxr.linux.no/source/include/linux/kernel.h?a=arm#L244> > const typeof( ((type <http://lxr.linux.no/ident?a=arm;i=type> > *)0)->member ) *__mptr = (ptr > <http://lxr.linux.no/ident?a=arm;i=ptr>); \ > 245 <http://lxr.linux.no/source/include/linux/kernel.h?a=arm#L245> > (type <http://lxr.linux.no/ident?a=arm;i=type> *)( (char *)__mptr > - offsetof <http://lxr.linux.no/ident?a=arm;i=offsetof>(type > <http://lxr.linux.no/ident?a=arm;i=type>,member) );}) > > Can someone please explain how the above macro works and in what > situations it is used ? Thanks. http://www.kroah.com/log/linux/container_of.html It's used all the time :) thanks, greg k-h -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
