[ This can be merged with uml-implement-get_wchan.patch ]
The previous get_wchan patch needed some more work. Joe Perches
suggested the use of bool where I was using a counter. It also turned
out not to work so well on x86_64, so I changed the algorithm a bit.
Instead of skipping one frame and looking for the next non-sched
symbol, it now looks for at least one scheduler frame, then returns
the first symbol seen above that.
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
---
arch/um/kernel/process.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)
Index: linux-2.6.22/arch/um/kernel/process.c
===================================================================
--- linux-2.6.22.orig/arch/um/kernel/process.c 2007-10-31 13:16:40.000000000 -0400
+++ linux-2.6.22/arch/um/kernel/process.c 2007-10-31 13:17:00.000000000 -0400
@@ -462,7 +462,8 @@ unsigned long arch_align_stack(unsigned
unsigned long get_wchan(struct task_struct *p)
{
- unsigned long stack_page, sp, ip, count = 0;
+ unsigned long stack_page, sp, ip;
+ bool seen_sched = 0;
if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
return 0;
@@ -482,14 +483,11 @@ unsigned long get_wchan(struct task_stru
while (sp < stack_page + THREAD_SIZE) {
ip = *((unsigned long *) sp);
- if (kernel_text_address(ip) && !in_sched_functions(ip)) {
- /*
- * Skip one valid IP, which will be the low-level UML
- * context switcher.
- */
- if (count++ == 1)
- return ip;
- }
+ if (in_sched_functions(ip))
+ /* Ignore everything until we're above the scheduler */
+ seen_sched = 1;
+ else if (kernel_text_address(ip) && seen_sched)
+ return ip;
sp += sizeof(unsigned long);
}
-
