[PATCH] CONFIG_EPOLL

From: Christopher Hoover <ch@murgatroid.com>

Here's a patch to drop some more text/data/bss out of 2.5.  This time
the ``victim'' is eventpollfs (epoll).

fs/Makefile

@@ -10,7 +10,9 @@ obj-y :=	open.o read_write.o file_table.o buffer.o \
 		namei.o fcntl.o ioctl.o readdir.o select.o fifo.o locks.o \
 		dcache.o inode.o attr.o bad_inode.o file.o dnotify.o \
 		filesystems.o namespace.o seq_file.o xattr.o libfs.o \
-		fs-writeback.o mpage.o direct-io.o aio.o eventpoll.o
+		fs-writeback.o mpage.o direct-io.o aio.o
+
+obj-$(CONFIG_EPOLL)	+= eventpoll.o
 
 obj-$(CONFIG_COMPAT) += compat.o
 

include/linux/eventpoll.h

@@ -40,12 +40,21 @@ asmlinkage long sys_epoll_ctl(int epfd, int op, int fd, struct epoll_event *even
 asmlinkage long sys_epoll_wait(int epfd, struct epoll_event *events, int maxevents,
 			       int timeout);
 
+#ifdef CONFIG_EPOLL
+
 /* Used to initialize the epoll bits inside the "struct file" */
 void eventpoll_init_file(struct file *file);
 
 /* Used in fs/file_table.c:__fput() to unlink files from the eventpoll interface */
 void eventpoll_release(struct file *file);
 
+#else
+
+static inline void eventpoll_init_file(struct file *file) {}
+static inline void eventpoll_release(struct file *file) {}
+
+#endif
+
 #endif /* #ifdef __KERNEL__ */
 
 #endif /* #ifndef _LINUX_EVENTPOLL_H */

init/Kconfig

@@ -125,6 +125,13 @@ config FUTEX
 	  support for "fast userspace mutexes".  The resulting kernel may not
 	  run glibc-based applications correctly.
 
+config EPOLL
+	bool "Enable eventpoll support" if EMBEDDED
+	default y
+	help
+	  Disabling this option will cause the kernel to be built without
+	  support for epoll family of system calls.
+
 endmenu		# General setup
 
 

kernel/sys.c

@@ -228,6 +228,9 @@ cond_syscall(sys_recvmsg)
 cond_syscall(sys_socketcall)
 cond_syscall(sys_futex)
 cond_syscall(compat_sys_futex)
+cond_syscall(sys_epoll_create)
+cond_syscall(sys_epoll_ctl)
+cond_syscall(sys_epoll_wait)
 
 static int set_one_prio(struct task_struct *p, int niceval, int error)
 {