Commit-ID: f893959b0898bd876673adbeb6798bdf25c034d7 Gitweb: http://git.kernel.org/tip/f893959b0898bd876673adbeb6798bdf25c034d7 Author: Oleg Nesterov <[email protected]> AuthorDate: Fri, 13 Mar 2015 18:30:30 +0100 Committer: Ingo Molnar <[email protected]> CommitDate: Mon, 23 Mar 2015 10:13:58 +0100
x86/fpu: Don't abuse drop_init_fpu() in flush_thread() flush_thread() -> drop_init_fpu() is suboptimal and confusing. It does drop_fpu() or restore_init_xstate() depending on !use_eager_fpu(). But flush_thread() too checks eagerfpu right after that, and if it is true then restore_init_xstate() just burns CPU for no reason. We are going to load init_xstate_buf again after we set used_math()/user_has_fpu(), until then the FPU state can't survive after switch_to(). Remove it, and change the "if (!use_eager_fpu())" to call drop_fpu(). While at it, clean up the tsk/current usage. Signed-off-by: Oleg Nesterov <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Fenghua Yu <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Pekka Riikonen <[email protected]> Cc: Quentin Casasnovas <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Suresh Siddha <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/kernel/process.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 6b05829..1d2ebad 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -132,17 +132,14 @@ void flush_thread(void) flush_ptrace_hw_breakpoint(tsk); memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array)); - drop_init_fpu(tsk); - /* - * Free the FPU state for non xsave platforms. They get reallocated - * lazily at the first use. - */ - if (!use_eager_fpu()) + if (!use_eager_fpu()) { + /* FPU state will be reallocated lazily at the first use. */ + drop_fpu(tsk); free_thread_xstate(tsk); - else if (!used_math()) { + } else if (!used_math()) { /* kthread execs. TODO: cleanup this horror. */ - if (WARN_ON(init_fpu(current))) - force_sig(SIGKILL, current); + if (WARN_ON(init_fpu(tsk))) + force_sig(SIGKILL, tsk); user_fpu_begin(); restore_init_xstate(); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
