From: Oleg Nesterov <oleg@redhat.com>
Date: Mon, 19 Jan 2015 18:52:12 +0000 (+0100)
Subject: x86/fpu: Don't abuse FPU in kernel threads if use_eager_fpu()
X-Git-Tag: omap-for-v4.1/fixes-rc1~189^2~11^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=110d7f7513bbb916b8654da9e2973ac5bed929a9;p=pandora-kernel.git

x86/fpu: Don't abuse FPU in kernel threads if use_eager_fpu()

AFAICS, there is no reason why kernel threads should have FPU context
even if use_eager_fpu() == T. Now that interrupted_kernel_fpu_idle()
does not check __thread_has_fpu() in the use_eager_fpu() case, we
can remove the init_fpu() code from eager_fpu_init() and change
flush_thread() called by do_execve() to initialize FPU.

Note: of course, the change in flush_thread() is horrible and must be
cleanuped. We need the new helper, and flush_thread() should return the
error if init_fpu() fails.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Suresh Siddha <sbsiddha@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/20150119185212.GD16427@redhat.com
Signed-off-by: Borislav Petkov <bp@suse.de>
---

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