This patchs adds the CONFIG_AIO option which allows to remove support
for asynchronous I/O operations, that are not necessarly used by
applications, particularly on embedded devices. As this is a
size-reduction option, it depends on CONFIG_EMBEDDED. It allows to
save ~7 kilobytes of kernel code/data:
text data bss dec hex filename
1115067 119180 217088 1451335 162547 vmlinux
1108025 119048 217088 1444161 160941 vmlinux.new
-7042 -132 0 -7174 -1C06 +/-
This patch has been originally written by Matt Mackall
<mpm@xxxxxxxxxxx>, and is part of the Linux Tiny project.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Matt Mackall <mpm@xxxxxxxxxxx>
Cc: bcrl@xxxxxxxxx
Cc: linux-aio@xxxxxxxxx
Cc: mpm@xxxxxxxxxxx
Cc: akpm@xxxxxxxxxxxxxxxxxxxx
---
fs/Makefile | 3 ++-
include/linux/aio.h | 9 +++++++++
init/Kconfig | 8 ++++++++
kernel/sys_ni.c | 5 +++++
kernel/sysctl.c | 2 ++
5 files changed, 26 insertions(+), 1 deletion(-)
Index: linuxdev/fs/Makefile
===================================================================
--- linuxdev.orig/fs/Makefile
+++ linuxdev/fs/Makefile
@@ -8,7 +8,7 @@
obj-y := open.o read_write.o file_table.o super.o \
char_dev.o stat.o exec.o pipe.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 filesystems.o namespace.o aio.o \
+ attr.o bad_inode.o file.o filesystems.o namespace.o \
seq_file.o xattr.o libfs.o fs-writeback.o \
pnode.o drop_caches.o splice.o sync.o utimes.o \
stack.o
@@ -27,6 +27,7 @@
obj-$(CONFIG_SIGNALFD) += signalfd.o
obj-$(CONFIG_TIMERFD) += timerfd.o
obj-$(CONFIG_EVENTFD) += eventfd.o
+obj-$(CONFIG_AIO) += aio.o
obj-$(CONFIG_COMPAT) += compat.o compat_ioctl.o
nfsd-$(CONFIG_NFSD) := nfsctl.o
Index: linuxdev/include/linux/aio.h
===================================================================
--- linuxdev.orig/include/linux/aio.h
+++ linuxdev/include/linux/aio.h
@@ -204,12 +204,21 @@
/* prototypes */
extern unsigned aio_max_size;
+#ifdef CONFIG_AIO
extern ssize_t wait_on_sync_kiocb(struct kiocb *iocb);
extern int aio_put_req(struct kiocb *iocb);
extern void kick_iocb(struct kiocb *iocb);
extern int aio_complete(struct kiocb *iocb, long res, long res2);
struct mm_struct;
extern void exit_aio(struct mm_struct *mm);
+#else
+static inline ssize_t wait_on_sync_kiocb(struct kiocb *iocb) { return 0; }
+static inline int aio_put_req(struct kiocb *iocb) { return 0; }
+static inline void kick_iocb(struct kiocb *iocb) { }
+static inline int aio_complete(struct kiocb *iocb, long res, long res2) { return 0; }
+struct mm_struct;
+static inline void exit_aio(struct mm_struct *mm) { }
+#endif /* CONFIG_AIO */
#define io_wait_to_kiocb(wait) container_of(wait, struct kiocb, ki_wait)
Index: linuxdev/init/Kconfig
===================================================================
--- linuxdev.orig/init/Kconfig
+++ linuxdev/init/Kconfig
@@ -724,6 +724,14 @@
option replaces shmem and tmpfs with the much simpler ramfs code,
which may be appropriate on small systems without swap.
+config AIO
+ bool "Enable AIO support" if EMBEDDED
+ default y
+ help
+ This option enables POSIX asynchronous I/O which may by used
+ by some high performance threaded applications. Disabling
+ this option saves about 7k.
+
config VM_EVENT_COUNTERS
default y
bool "Enable VM event counters for /proc/vmstat" if EMBEDDED
Index: linuxdev/kernel/sys_ni.c
===================================================================
--- linuxdev.orig/kernel/sys_ni.c
+++ linuxdev/kernel/sys_ni.c
@@ -125,6 +125,11 @@
cond_syscall(sys_vm86);
cond_syscall(compat_sys_ipc);
cond_syscall(compat_sys_sysctl);
+cond_syscall(sys_io_setup);
+cond_syscall(sys_io_destroy);
+cond_syscall(sys_io_submit);
+cond_syscall(sys_io_cancel);
+cond_syscall(sys_io_getevents);
/* arch-specific weak syscall entries */
cond_syscall(sys_pciconfig_read);
Index: linuxdev/kernel/sysctl.c
===================================================================
--- linuxdev.orig/kernel/sysctl.c
+++ linuxdev/kernel/sysctl.c
@@ -1290,6 +1290,7 @@
.extra1 = &zero,
.extra2 = &two,
},
+#ifdef CONFIG_AIO
{
.procname = "aio-nr",
.data = &aio_nr,
@@ -1304,6 +1305,7 @@
.mode = 0644,
.proc_handler = &proc_doulongvec_minmax,
},
+#endif /* CONFIG_AIO */
#ifdef CONFIG_INOTIFY_USER
{
.ctl_name = FS_INOTIFY,
--
Thomas Petazzoni, Free Electrons
Kernel, drivers and embedded Linux development,
consulting, training and support.
http://free-electrons.com
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