[SSI] openssi/kernel/fs exec.c,1.12,1.13

Update of /cvsroot/ssic-linux/openssi/kernel/fs
In directory sfp-cvsdas-3.v30.ch3.sourceforge.com:/tmp/cvs-serv23888/fs

Modified Files:
      Tag: OPENSSI-FC
	exec.c 
Log Message:
VPROC:
- Fix select_bad_process() NULL p_vproc pointer dereference.
- Fix de_thread() related issues:
  - Fix de_thread() calling VPOP_RECLAIM_CHILD() while holding spin_lock(task->p
roc_lock). Code path might sleep.
  - Fix NULL p_vproc pointer dereference when thread group leader is exiting, ha
s PF_FORKNOEXEC flag, and has lost race with de_thread(). Affects exit_notify(),
 forget_original_parent(), and will_become_orphaned_pgrp(). When p_vproc is NULL
 the exiting process reaps itself.
  - Fix dpvproc_nocldwait_async_handler() NULL pointer dereference due to failed
 lookup for vproc of new parent when lost race with de_thread(). (#ifdef RELEASE
_TASK_LEADER_GONE__VPROC_FIX)
  - New PVPOP_SWITCH_PID() to switch VProc PID of process doing de_thread().
  - New PV_DETHREAD_REAP flag is set during de_thread() to indicate to child rea
per to reap thread group leader without delay.
  - Fix oops in do_notify_resume() path due to NULL pointer dereference. p_vproc
 is NULL after bad fork.

VPROC (#ifdef VPROC_RELEASE__REFCNT_RACE_FIX):
- Fix extra VPROC_RELE() on PVPOP_RMV_PGRP_LIST() -ESRCH error.
- Fix PVPOP_REAP() extra dpvproc_remove_pgrp_leader_member_care() on PVPOP_RMV_P
GRP_LIST() -EBUSY error; was typo in if-test.
- PVPOP_REAP() no longer does async PVPOP_RMV_PGRP_LIST(); now sync. Don't see h
ow reaping parent can hold PGRP LOCK in PVPOP_REAP() path.
- Fix exit_vproc() did not decrement vproc reference for process group leader on
 member node. This is in do_fork() error path.

VPROC (#ifdef VPROC_CONTINUE):
- Fix dpvproc_nocldwait_async_handler() deadlock on PVPOP_REAP() -EBUSY due to d
elay_group_leader(). PV_REAPER_RETRY flag is set and group leader is re-inserted
 into the queue so that the remaining threads in thread group can be reaped by t
his handler to remove the delay_group_leader() condition.
- Regression:
  - Fix pproc_reap() should succeed, but returns -EBUSY when process is a thread
 group leader in non-empty thread group and is already in EXIT_DEAD state.


Index: exec.c
===================================================================
RCS file: /cvsroot/ssic-linux/openssi/kernel/fs/exec.c,v
retrieving revision 1.12
retrieving revision 1.13
diff -u -d -r1.12 -r1.13
--- exec.c	27 Oct 2009 03:18:30 -0000	1.12
+++ exec.c	17 Dec 2009 05:46:50 -0000	1.13
@@ -56,8 +56,12 @@
 
 #ifdef CONFIG_SSI
 #include <cluster/nsc.h>		/* for PID_DATA */
-#include <linux/vproc.h>
 #include <cluster/ssi/load_level.h>
+#ifdef VPROC_RCU_LIST
+#include <linux/dpvproc.h>
+#else
+#include <linux/vproc.h>
+#endif
 #endif
 
 int core_uses_pid;
@@ -761,15 +765,7 @@
 
 		ptrace_unlink(current);
 		ptrace_unlink(leader);
-#ifdef CONFIG_VPROC
-		write_unlock_irq(&tasklist_lock);
-		if (VPOP_RECLAIM_CHILD(current->p_vproc, leader->ppid,0,0) < 0)
-			printk("de_thread: failed to reclaim child \n");
-
-		if (VPOP_RECLAIM_CHILD(leader->p_vproc, 2, 0, 0) < 0)
-			printk("de_thread: failed to reclaim leader \n");
-		write_lock_irq(&tasklist_lock);
-#else
+#ifndef CONFIG_VPROC
 		remove_parent(current);
 		remove_parent(leader);
 #endif
@@ -807,6 +803,37 @@
 		if (exit_state != EXIT_ZOMBIE)
 			BUG();
 #ifdef CONFIG_VPROC
+		/*
+		 * CPU0			CPU1
+		 * parent do_wait()	new program de_thread()
+		 *
+		 * read_lock(&tasklist_lock)
+		 * delay_group_leader(leader) == TRUE
+		 * read_unlock(&tasklist_lock)
+		 * not eligible for reap
+		 *			write_lock_irq(&tasklist_lock)
+		 *			switch_exec_pids()
+		 *			write_unlock_irq(&tasklist_lock)
+		 */
+
+		/* SSI: We cannot reclaim before switch_exec_pids() above
+		 * due to spin_lock(task->proc_lock).
+		 */
+		if (VPOP_RECLAIM_CHILD(current->p_vproc, leader->ppid,0,0) < 0)
+			printk("de_thread: failed to reclaim child \n");
+
+		/* SSI: Could race with VPOP_CLEANUP_VPROC_RELATIONS() */
+		if ((count = VPOP_RECLAIM_CHILD(leader->p_vproc, 2, 0, 0)) < 0)
+			printk("de_thread: failed to reclaim leader %d\n", count);
+
+#ifdef VPROC_CONTINUE
+		/* Set the flag so child reaper will ignore result of
+		 * delay_group_leader(leader) and reap leader immediately.
+		 */
+		VPROC_LOCK_FLAG(vl, "de_thread");
+		PVP(vl)->pvp_flag |=  PV_DETHREAD_REAP;
+		VPROC_UNLOCK_FLAG(vl, "de_thread");
+#endif
 		do_notify_parent(leader, SIGCHLD, 0, 0);
 #ifdef VPROC_RELEASE__REFCNT_RACE_FIX
 #ifdef TASK_HOLD_VPROC
@@ -814,10 +841,8 @@
 #else
 		VPROC_RELE(parent->p_vproc, "temp de_thread(parent of leader)");
 #endif
-#ifdef VPROC_HOLD_ZERO_GET_TASK
-		VPROC_RELE(vl, "de_thread(leader)");
-#endif
 #endif
+#ifdef SSI_SKIP
 #ifdef DE_THREAD__OOPS_FIX
 		/* [ ssic-linux-Bugs-2000692 ]
 		 * Wait for leader to get reaped.
@@ -826,6 +851,22 @@
 		while (atomic_read(&sig->count) > 1)
 			yield();
 #endif
+#endif /* SSI_SKIP */
+#ifdef VPROC_RCU_LIST
+#ifdef TASK_HOLD_VPROC
+		/* Wait for leader to remove self from process group */
+		while (atomic_read(&vl->vp_ref_cnt) > 5 ||
+				PVP(current->p_vproc)->pvp_pgrpl == vl)
+			yield();
+		/* Could possibly just wait for PV_WAITED ? */
+		SSI_ASSERT(PVP(vl)->pvp_flag & PV_WAITED);
+#ifdef VPROC_HOLD_ZERO_GET_TASK
+		VPROC_RELE(vl, "de_thread(leader)");
+#endif
+#endif
+		/* Now that the leader is reaped switch vproc pid */
+		PVPOP_SWITCH_PID(current->p_vproc, current->pid);
+#endif /* VPROC_RCU_LIST */
 #else
 		release_task(leader);
 #endif /* !VPROC */


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