linux-kernel - Re: [PATCH 1/1] x86/cpu: kill eager_fpu_init

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Date:	Mon, 16 Mar 2015 13:44:05 +0100
From:	Borislav Petkov <bp@...e.de>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Dave Hansen <dave.hansen@...el.com>,
	Ingo Molnar <mingo@...nel.org>,
	Andy Lutomirski <luto@...capital.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Pekka Riikonen <priikone@....fi>,
	Rik van Riel <riel@...hat.com>,
	Suresh Siddha <sbsiddha@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"Yu, Fenghua" <fenghua.yu@...el.com>,
	Quentin Casasnovas <quentin.casasnovas@...cle.com>
Subject: Re: [PATCH 1/1] x86/cpu: kill eager_fpu_init_bp()

On Sat, Mar 14, 2015 at 04:13:34PM +0100, Oleg Nesterov wrote:
> Now that eager_fpu_init_bp() does setup_init_fpu_buf() and nothing else
> we can remove it and move this code into its "caller", eager_fpu_init().
> 
> This avoids the confusing games with "static __refdata void (*boot_func)".
> init_xstate_buf can be NULL only on boot, so it is safe to the "__init"
> setup_init_fpu_buf() function, just we need to add the "__init_refok"
> marker.
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>

Applied, thanks.

I added a note above eager_fpu_init() why it is marked as __init_refok:

---
From: Oleg Nesterov <oleg@...hat.com>
Date: Sat, 14 Mar 2015 16:13:34 +0100
Subject: [PATCH] x86/fpu: Kill eager_fpu_init_bp()

Now that eager_fpu_init_bp() does setup_init_fpu_buf() only and
nothing else, we can remove it and move this code into its "caller",
eager_fpu_init().

This avoids the confusing games with "static __refdata void (*boot_func)":

init_xstate_buf can be NULL only during boot, so it is safe to call the
__init-annotated setup_init_fpu_buf() function in eager_fpu_init(), we
just need to mark it as __init_refok.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Pekka Riikonen <priikone@....fi>
Cc: Rik van Riel <riel@...hat.com>
Cc: Suresh Siddha <sbsiddha@...il.com>
Cc: Fenghua Yu <fenghua.yu@...el.com>
Cc: Quentin Casasnovas <quentin.casasnovas@...cle.com>
Link: http://lkml.kernel.org/r/20150314151334.GC13029@redhat.com
Signed-off-by: 
---
 arch/x86/kernel/xsave.c | 20 +++++++-------------
 1 file changed, 7 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c
index ada8df7b89c0..87a815b85f3e 100644
--- a/arch/x86/kernel/xsave.c
+++ b/arch/x86/kernel/xsave.c
@@ -678,16 +678,12 @@ void xsave_init(void)
 	this_func();
 }
 
-static inline void __init eager_fpu_init_bp(void)
-{
-	if (!init_xstate_buf)
-		setup_init_fpu_buf();
-}
-
-void eager_fpu_init(void)
+/*
+ * setup_init_fpu_buf() is __init and it is OK to call it here because
+ * init_xstate_buf will be unset only once during boot.
+ */
+void __init_refok eager_fpu_init(void)
 {
-	static __refdata void (*boot_func)(void) = eager_fpu_init_bp;
-
 	WARN_ON(used_math());
 	current_thread_info()->status = 0;
 
@@ -699,10 +695,8 @@ void eager_fpu_init(void)
 		return;
 	}
 
-	if (boot_func) {
-		boot_func();
-		boot_func = NULL;
-	}
+	if (!init_xstate_buf)
+		setup_init_fpu_buf();
 }
 
 /*
-- 
2.3.3

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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