From mboxrd@z Thu Jan 1 00:00:00 1970 From: Robin Holt Date: Fri, 18 May 2007 18:46:52 +0000 Subject: [PATCH 2/2] Only unwind non-running tasks. Message-Id: <20070518184652.GC9217@lnx-holt.americas.sgi.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org 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 Index: linux-tot-20070517/arch/ia64/kernel/process.c =================================--- linux-tot-20070517.orig/arch/ia64/kernel/process.c 2007-05-18 10:14:45.485516967 -0500 +++ linux-tot-20070517/arch/ia64/kernel/process.c 2007-05-18 10:15:10.340573728 -0500 @@ -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);