Re: [PATCH] Fix sparc TIF_USEDFPU flag atomicity

From: William Lee Irwin III
Date: Sat Mar 10 2007 - 03:27:24 EST


On Sat, Mar 10, 2007 at 03:17:43AM -0500, Mathieu Desnoyers wrote:
> @@ -348,7 +348,7 @@ void exit_thread(void)
> #ifndef CONFIG_SMP
> if(last_task_used_math == current) {
> #else
> - if(current_thread_info()->flags & _TIF_USEDFPU) {
> + if(test_ti_thread_flag(current_thread_info(), TIF_USEDFPU)) {
> #endif
> /* Keep process from leaving FPU in a bogon state. */
> put_psr(get_psr() | PSR_EF);

Oh dear. Could we bit a bit more idiomatic here? For instance,
something like:

Index: linux-2.6/arch/sparc/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/sparc/kernel/process.c 2007-03-09 23:24:12.934472032 -0800
+++ linux-2.6/arch/sparc/kernel/process.c 2007-03-09 23:29:26.592346376 -0800
@@ -348,7 +348,7 @@
#ifndef CONFIG_SMP
if(last_task_used_math == current) {
#else
- if(current_thread_info()->flags & _TIF_USEDFPU) {
+ if (test_thread_flag(TIF_USEDFPU)) {
#endif
/* Keep process from leaving FPU in a bogon state. */
put_psr(get_psr() | PSR_EF);
@@ -357,7 +357,7 @@
#ifndef CONFIG_SMP
last_task_used_math = NULL;
#else
- current_thread_info()->flags &= ~_TIF_USEDFPU;
+ clear_thread_flag(TIF_USEDFPU);
#endif
}
}
@@ -371,7 +371,7 @@
#ifndef CONFIG_SMP
if(last_task_used_math == current) {
#else
- if(current_thread_info()->flags & _TIF_USEDFPU) {
+ if (test_thread_flag(TIF_USEDFPU)) {
#endif
/* Clean the fpu. */
put_psr(get_psr() | PSR_EF);
@@ -380,7 +380,7 @@
#ifndef CONFIG_SMP
last_task_used_math = NULL;
#else
- current_thread_info()->flags &= ~_TIF_USEDFPU;
+ clear_thread_flag(TIF_USEDFPU);
#endif
}

@@ -466,13 +466,13 @@
#ifndef CONFIG_SMP
if(last_task_used_math == current) {
#else
- if(current_thread_info()->flags & _TIF_USEDFPU) {
+ if (test_thread_flag(TIF_USEDFPU)) {
#endif
put_psr(get_psr() | PSR_EF);
fpsave(&p->thread.float_regs[0], &p->thread.fsr,
&p->thread.fpqueue[0], &p->thread.fpqdepth);
#ifdef CONFIG_SMP
- current_thread_info()->flags &= ~_TIF_USEDFPU;
+ clear_thread_flag(TIF_USEDFPU);
#endif
}

@@ -609,13 +609,13 @@
return 1;
}
#ifdef CONFIG_SMP
- if (current_thread_info()->flags & _TIF_USEDFPU) {
+ if (test_thread_flag(TIF_USEDFPU)) {
put_psr(get_psr() | PSR_EF);
fpsave(&current->thread.float_regs[0], &current->thread.fsr,
&current->thread.fpqueue[0], &current->thread.fpqdepth);
if (regs != NULL) {
regs->psr &= ~(PSR_EF);
- current_thread_info()->flags &= ~(_TIF_USEDFPU);
+ clear_thread_flag(TIF_USEDFPU);
}
}
#else
Index: linux-2.6/arch/sparc/kernel/traps.c
===================================================================
--- linux-2.6.orig/arch/sparc/kernel/traps.c 2007-03-09 23:40:33.994379450 -0800
+++ linux-2.6/arch/sparc/kernel/traps.c 2007-03-09 23:44:07.910569839 -0800
@@ -259,7 +259,7 @@
} else {
fpload(&current->thread.float_regs[0], &current->thread.fsr);
}
- current_thread_info()->flags |= _TIF_USEDFPU;
+ set_thread_flag(TIF_USEDFPU);
#endif
}

@@ -290,7 +290,7 @@
#ifndef CONFIG_SMP
if(!fpt) {
#else
- if(!(task_thread_info(fpt)->flags & _TIF_USEDFPU)) {
+ if (!test_tsk_thread_flag(fpt, TIF_USEDFPU)) {
#endif
fpsave(&fake_regs[0], &fake_fsr, &fake_queue[0], &fake_depth);
regs->psr &= ~PSR_EF;
@@ -333,7 +333,7 @@
/* nope, better SIGFPE the offending process... */

#ifdef CONFIG_SMP
- task_thread_info(fpt)->flags &= ~_TIF_USEDFPU;
+ clear_tsk_thread_flag(fpt, TIF_USEDFPU);
#endif
if(psr & PSR_PS) {
/* The first fsr store/load we tried trapped,
-
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