[PATCH RESEND] Ensure that kernel_init_freeable() is not inlined into non __init code

From: Vineet Gupta
Date: Fri Dec 21 2012 - 01:56:13 EST

Commit d6b2123802d "make sure that we always have a return path from
kernel_execve()" reshuffled kernel_init()/init_post() to ensure that
kernel_execve() has a caller to return to.

It removed __init annotation for kernel_init() and introduced/calls a
new routine kernel_init_freeable(). Latter however is inlined by any
reasonable compiler (ARC gcc 4.4 in this case), causing slight code

This patch forces kernel_init_freeable() as noinline reducing the .text

bloat-o-meter vmlinux vmlinux_new
add/remove: 1/0 grow/shrink: 0/1 up/down: 374/-334 (40)
function old new delta
kernel_init_freeable - 374 +374 (.init.text)
kernel_init 628 294 -334 (.text)

Just for documentation, here's what Al's orig commit did.


THREAD __init kernel_init()

init_post() --> forced to be noinline
return 0;

free_initmem() --> reaps caller kernel_init()


THREAD kernel_init()
kernel_init_freeable() --> __init tagged
free_initmem() --> reaps kernel_init_freeable()
run_init_process "init"

Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
CC: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
CC: Jim Cromie <jim.cromie@xxxxxxxxx>
CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
CC: "H. Peter Anvin" <hpa@xxxxxxxxxxxxxxx>
CC: linux-kernel@xxxxxxxxxxxxxxx
init/main.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/init/main.c b/init/main.c
index 85d69df..92d728a 100644
--- a/init/main.c
+++ b/init/main.c
@@ -802,7 +802,7 @@ static int run_init_process(const char *init_filename)
(const char __user *const __user *)envp_init);

-static void __init kernel_init_freeable(void);
+static noinline void __init kernel_init_freeable(void);

static int __ref kernel_init(void *unused)
@@ -845,7 +845,7 @@ static int __ref kernel_init(void *unused)
"See Linux Documentation/init.txt for guidance.");

-static void __init kernel_init_freeable(void)
+static noinline void __init kernel_init_freeable(void)
* Wait until kthreadd is all set-up.

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