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Commit 6ae38488 authored by Robin Holt's avatar Robin Holt Committed by Tony Luck
Browse files

[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: default avatarRobin Holt <holt@sgi.com>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent e2e6fe7b

arch/ia64/kernel/process.c

+5 −0
Original line number Original line Diff line number Diff line
@@ -763,6 +763,9 @@ get_wchan (struct task_struct *p) 
	unsigned long ip;

	unsigned long ip;

	int count = 0;

	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

	 * Note: p may not be a blocked task (it could be current or

	 * another process running on some other CPU.  Rather than

	 * 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);

	unw_init_from_blocked_task(&info, p);

	do {

	do {

		if (p->state == TASK_RUNNING)

			return 0;

		if (unw_unwind(&info) < 0)

		if (unw_unwind(&info) < 0)

			return 0;

			return 0;

		unw_get_ip(&info, &ip);

		unw_get_ip(&info, &ip);