Module: xenomai-head
Branch: master
Commit: da20c20d4b4d892d40c657ad1d32ddb6d0ceb47c
URL:
http://git.xenomai.org/?p=xenomai-head.git;a=commit;h=da20c20d4b4d892d40c657ad1d32ddb6d0ceb47c
Author: Philippe Gerum <r...@xenomai.org>
Date: Wed Oct 27 17:42:05 2010 +0200
nucleus: clear kthread stack while setting its TCB
Zero the stack space allocated for a kthread while initializing its
control block, so that xnarch_init_thread() may assume it gets clean
memory.
Zeroing such memory in xnthread_init() is better for latency, since it
runs with hw interrupts enabled, unlike xnarch_init_thread().
---
include/asm-powerpc/bits/pod.h | 6 +++++-
ksrc/nucleus/thread.c | 10 +++++++---
2 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/include/asm-powerpc/bits/pod.h b/include/asm-powerpc/bits/pod.h
index fffa91f..f800391 100644
--- a/include/asm-powerpc/bits/pod.h
+++ b/include/asm-powerpc/bits/pod.h
@@ -180,10 +180,14 @@ static inline void xnarch_init_thread(xnarchtcb_t * tcb,
struct pt_regs *childregs;
unsigned long sp;
+ /*
+ * Stack space is guaranteed to have been fully zeroed. We do
+ * this earlier in xnthread_init() which runs with interrupts
+ * on, to reduce latency.
+ */
sp = (unsigned long)tcb->stackbase + tcb->stacksize;
sp -= sizeof(struct pt_regs);
childregs = (struct pt_regs *)sp;
- memset(childregs, 0, sizeof(*childregs));
sp -= STACK_FRAME_OVERHEAD;
tcb->ts.ksp = sp;
diff --git a/ksrc/nucleus/thread.c b/ksrc/nucleus/thread.c
index ac38144..54b0796 100644
--- a/ksrc/nucleus/thread.c
+++ b/ksrc/nucleus/thread.c
@@ -52,10 +52,12 @@ int xnthread_init(struct xnthread *thread,
{
unsigned int stacksize = attr->stacksize;
xnflags_t flags = attr->flags;
+ struct xnarchtcb *tcb;
int ret;
/* Setup the TCB. */
- xnarch_init_tcb(xnthread_archtcb(thread));
+ tcb = xnthread_archtcb(thread);
+ xnarch_init_tcb(tcb);
flags &= ~XNSUSP;
#ifndef CONFIG_XENO_HW_FPU
@@ -87,13 +89,15 @@ int xnthread_init(struct xnthread *thread,
}
#endif
#else
- ret = xnarch_alloc_stack(xnthread_archtcb(thread), stacksize);
+ ret = xnarch_alloc_stack(tcb, stacksize);
if (ret) {
xnlogerr("%s: no stack for kernel thread '%s' (raise
CONFIG_XENO_OPT_SYS_STACKPOOLSZ)\n",
__FUNCTION__, attr->name);
return ret;
}
#endif
+ if (stacksize)
+ memset(xnarch_stack_base(tcb), 0, stacksize);
if (attr->name)
xnobject_copy_name(thread->name, attr->name);
@@ -172,7 +176,7 @@ int xnthread_init(struct xnthread *thread,
fail:
#if CONFIG_XENO_OPT_SYS_STACKPOOLSZ > 0
- xnarch_free_stack(xnthread_archtcb(thread));
+ xnarch_free_stack(tcb);
#endif
return ret;
}
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