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[IA64] Only unwind non-running tasks. 

Unwinding a running task has proven problematic.

In one instance, the running task was attempting to unwind itself and
received an interrupt between when get_wchan allocated local variables on
the stack and when unw_init_from_blocked_task was called which resulted
in unw_init_frame_info to place this tasks task_struct pointer over the
switch stack's ar_bspstore entry.

Signed-off-by: Robin Holt <holt@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This commit is contained in:
Robin Holt 2007-05-18 13:46:52 -05:00 committed by Tony Luck
parent e2e6fe7bb6
commit 6ae384884d
1 changed files with 5 additions and 0 deletions
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5
arch/ia64/kernel/process.c
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@ -763,6 +763,9 @@ get_wchan (struct task_struct *p)
unsigned long ip;
int count = 0;
if (!p || p == current || p->state == TASK_RUNNING)
return 0;
/*
* Note: p may not be a blocked task (it could be current or
* another process running on some other CPU. Rather than
@ -773,6 +776,8 @@ get_wchan (struct task_struct *p)
*/
unw_init_from_blocked_task(&info, p);
do {
if (p->state == TASK_RUNNING)
return 0;
if (unw_unwind(&info) < 0)
return 0;
unw_get_ip(&info, &ip);