[SSI] openssi/kernel/fs/proc base.c,1.32,1.33

Update of /cvsroot/ssic-linux/openssi/kernel/fs/proc
In directory sfp-cvsdas-3.v30.ch3.sourceforge.com:/tmp/cvs-serv784/fs/proc

Modified Files:
      Tag: OPENSSI-FC
	base.c 
Log Message:
- proc_pid_make_inode, proc_pid_lookup, proc_task_lookup: Use revised proc_ssi_task(). Avoid VPROC MOVEMENT LOCK since we could be in time-critical VFS lookup code path. Avoid waiting for process migration.
- proc_pid_make_inode: reduce redundant code.
- proc_pident_lookup, proc_lookupfd: No need to acquire VPROC MOVEMENT LOCK for revised proc_pid_make_inode().
- proc_task_readdir: no need for seperate code path for local listing. remove redundant.
- vproc_migrate_local: no need to acquire VPROC MOVEMENT LOCK since setup_execnode_move() will check move header list for existing entries.

(#ifdef TASK_HOLD_VPROC)
- proc_permission, ssi_mounts_open, ssi_oom_adjust: no need to acquire VPROC MOVEMENT LOCK since the caller holds inode reference which means the task_struct reference held by PROC_I()->task is safe against concurrent process migration.
- oom_adjust_read, oom_adjust_write: remove ugly type casting. caller ensures PROC_I()->task is valid.


Index: base.c
===================================================================
RCS file: /cvsroot/ssic-linux/openssi/kernel/fs/proc/base.c,v
retrieving revision 1.32
retrieving revision 1.33
diff -u -d -r1.32 -r1.33
--- base.c	15 Dec 2010 06:53:20 -0000	1.32
+++ base.c	17 Jan 2011 07:00:28 -0000	1.33
@@ -506,22 +506,11 @@
 
 static int proc_permission(struct inode *inode, int mask, struct nameidata *nd)
 {
-#ifdef TASK_HOLD_VPROC
-	struct vproc *vp;
-	int error;
-#endif
 	if (generic_permission(inode, mask, NULL) != 0)
 		return -EACCES;
 #ifdef CONFIG_SSI
 #ifdef TASK_HOLD_VPROC
-	vp = proc_vproc(inode);
-	error = VPROC_HOLD_MOVEMENT_LOCAL(vp, "proc_permission");
-	if (error == -EREMOTE)
-		return 0;
-
-	error = proc_check_root(inode);
-	VPROC_RELEASE_MOVEMENT(vp, "proc_permission");
-	return error;
+	return (!proc_task(inode)) ? 0 : proc_check_root(inode);
 #else
 	/* 
 	 * FIXME!! SSI_XXX Why do we skip the below proc_check_root ? 
@@ -646,31 +635,13 @@
 {
 	int error;
 	struct nameidata nd;
-#ifndef VPROC_HOLD_ZERO_GET_TASK
-	struct task_struct *task = proc_ssi_task(proc_vproc(inode));
 
-	if (task) {
-#else
 #ifdef TASK_HOLD_VPROC
-	struct vproc *vp = proc_vproc(inode);
-
-	error = VPROC_HOLD_MOVEMENT_LOCAL(vp, "ssi_mounts_open");
-	if (error != -EREMOTE) {
-#else
-	if (PVP(proc_vproc(inode))->pvp_flag & PV_IS_LOCAL) {
-#endif
-#endif
-		int ret;
-		ret = mounts_open(inode, file);
-#ifndef VPROC_HOLD_ZERO_GET_TASK
-		put_task_struct(task);
+	if (proc_task(inode))
+		return mounts_open(inode, file);
 #else
-#ifdef TASK_HOLD_VPROC
-		VPROC_RELEASE_MOVEMENT(vp, "ssi_mounts_open");
-#endif
+#error deprecated. pls define TASK_HOLD_VPROC
 #endif
-		return ret;
-	}
 
 	/* SSI_XXX: Process is remote...however since we currently dont
 	 * support private namespaces, there is no need to go to the
@@ -943,11 +914,7 @@
 static ssize_t oom_adjust_read(struct file *file, char *buf,
 				size_t count, loff_t *ppos)
 {
-#ifndef CONFIG_SSI
 	struct task_struct *task = proc_task(file->f_dentry->d_inode);
-#else
-	struct task_struct *task = (struct task_struct *)file;
-#endif
 	char buffer[8];
 	size_t len;
 	int oom_adjust = task->oomkilladj;
@@ -967,11 +934,7 @@
 static ssize_t oom_adjust_write(struct file *file, const char *buf,
 				size_t count, loff_t *ppos)
 {
-#ifndef CONFIG_SSI
 	struct task_struct *task = proc_task(file->f_dentry->d_inode);
-#else
-	struct task_struct *task = (struct task_struct *)file;
-#endif
 	char buffer[8], *end;
 	int oom_adjust;
 
@@ -997,22 +960,18 @@
 static ssize_t ssi_oom_adjust(struct file *file, char *buf,
 				size_t count, loff_t *ppos, int type)
 {
-	struct vproc *vp = proc_vproc(file->f_dentry->d_inode);
 #ifdef TASK_HOLD_VPROC
-	int ret;
-
-	ret = VPROC_HOLD_MOVEMENT_LOCAL(vp, "ssi_oom_adjust");
-	if (ret == -EREMOTE)
+	if (!proc_task(file->f_dentry->d_inode))
 		return -EREMOTE;
 
 	if (!type)
-		ret = oom_adjust_read((struct file *) PVP(vp)->pvp_pproc, buf, count, ppos);
+		return oom_adjust_read(file, buf, count, ppos);
 	else
-		ret = oom_adjust_write((struct file *) PVP(vp)->pvp_pproc, buf, count, ppos);
-
-	VPROC_RELEASE_MOVEMENT(vp, "ssi_oom_adjust");
-	return ret;
+		return oom_adjust_write(file, buf, count, ppos);
 #else
+#error deprecated. use TASK_HOLD_VPROC
+	struct vproc *vp = proc_vproc(file->f_dentry->d_inode);
+
 	if (PVP(vp)->pvp_flag & PV_IS_LOCAL) {
 		struct task_struct *task = PVP(vp)->pvp_pproc;
 
@@ -1464,7 +1423,6 @@
 
 
 #ifdef CONFIG_SSI
-/* Called with VPROC_HOLD_MOVEMENT on vproc. */
 static struct inode *
 proc_pid_make_inode(struct super_block * sb, struct vproc *vp, int ino, int *tgid)
 #else
@@ -1488,70 +1446,50 @@
 	ei = PROC_I(inode);
 
 #ifdef CONFIG_SSI
-	if (PVP(vp)->pvp_flag & PV_IS_LOCAL) {
-#ifdef VPROC_HOLD_ZERO_GET_TASK
-		task = PVP(vp)->pvp_pproc;
-
-		if (!pid_alive(task))
-			goto out_unlock;
-#else
-		task = proc_ssi_task(vp);
-		if (task)
-			goto out_unlock;
-
-		if (!pid_alive(task)) {
-			put_task_struct(task);
-			goto out_unlock;
-		}
-#endif
-
-		euid = task->euid;
-		egid = task->egid;
-		dumpable = task_dumpable(task);
-
-		if (tgid)
-			*tgid = task->tgid;
-#ifndef VPROC_HOLD_ZERO_GET_TASK
-		put_task_struct(task);
-#endif
-	} else {
-		if (current->pid == vp->vp_pid) {
+	task = proc_ssi_task(vp);
+	if (task || vproc_migrating(vp)) {
+		if (!task) {
 			/* process is migrating here, no need to go remote
 			 * since /proc inodes get created...create local
 			 * entry and use current's values, since they
 			 * have just been copied in.
 			 */
 			task = current;
-			euid = task->euid;
-			egid = task->egid;
+			get_task_struct(task);
 			dumpable = 1;
-			if (tgid)
-				*tgid = task->tgid;
 		} else {
-			/*
-			 * Task on remote node. Get the attributes from remote 
-			 * node
-			 */
-			if (PVPOP_PROCFS_GETATTR(vp, 0, 0, &dumpable, &euid, &egid, tgid))
+			if (!pid_alive(task)) {
+				put_task_struct(task);
 				goto out_unlock;
-#ifdef TASK_HOLD_VPROC
-			task = NULL;
-#endif
+			}
+			dumpable = task_dumpable(task);
 		}
+		euid = task->euid;
+		egid = task->egid;
+		if (tgid)
+			*tgid = task->tgid;
+#ifndef TASK_HOLD_VPROC
+		put_task_struct(task);
+#endif
+	} else {
+		/*
+		 * Task on remote node. Get the attributes from remote
+		 * node
+		 */
+		if (PVPOP_PROCFS_GETATTR(vp, 0, 0, &dumpable, &euid, &egid, tgid))
+			goto out_unlock;
 	}
 
 	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 	inode->i_ino = fake_ino(vp->vp_pid, ino);
 
+	SSI_ASSERT(ei->task == NULL);
 #ifdef TASK_HOLD_VPROC
-	/* RT: Prevent proc_dentry dput() modifying bogus task_struct
-	 * due to migration.
+	/* Prevent proc_dentry dput() modifying bogus task_struct
+	 * due to migration.	-Roger
 	 */
-	/* grab the reference to task. */
-	if (task) {
-		get_task_struct(task);
+	if (task)
 		ei->task = task;
-	}
 #endif
 	/*
 	 * grab the reference to vproc.
@@ -1566,6 +1504,7 @@
 		inode->i_gid = egid;
 	}
 #if 0
+	/* TODO: clustered security infrastructure */
 	if (task)
 		security_task_to_inode(task, inode);
 #endif
@@ -1603,22 +1542,6 @@
 
 /* dentry stuff */
 
-#ifdef CONFIG_SSI
-/* Determine whether pid is migrating in */
-static inline int vproc_migrating(struct vproc *vp)
-{
-#ifdef TASK_HOLD_VPROC
-	/* SSI_ASSERT(current->p_vproc == vp); */
-	return (current->ppid == 2 &&
-		current->epid != vp->vp_pid &&
-		current->pid == vp->vp_pid);
-#else
-	return (current->ppid == 2 && current->p_vproc->vp_pid != vp->vp_pid &&
-			current->pid == vp->vp_pid);
-#endif
-}
-#endif /* CONFIG_SSI */
-
 /*
  *	Exceptional case: normally we are not allowed to unhash a busy
  * directory. In this case, however, we can do it - no aliasing problems
@@ -1823,10 +1746,7 @@
 		goto out;
 #ifdef CONFIG_SSI
 	/* SSI: we let proc_pid_make_inode() perform the pid_alive() check */
-	VPROC_HOLD_MOVEMENT(proc_vproc(dir), "proc_lookupfd");
-
 	inode = proc_pid_make_inode(dir->i_sb, proc_vproc(dir), PROC_TID_FD_DIR+fd, NULL);
-	VPROC_RELEASE_MOVEMENT(proc_vproc(dir), "proc_lookupfd");
 #else
 	if (!pid_alive(task))
 		goto out;
@@ -2030,11 +1950,7 @@
 
 	error = -EINVAL;
 #ifdef CONFIG_SSI
-	VPROC_HOLD_MOVEMENT(proc_vproc(dir), "proc_pident_lookup");
-
 	inode = proc_pid_make_inode(dir->i_sb, proc_vproc(dir), p->type, NULL);
-
-	VPROC_RELEASE_MOVEMENT(proc_vproc(dir), "proc_pident_lookup");
 #else
 	inode = proc_pid_make_inode(dir->i_sb, task, p->type);
 #endif
@@ -2380,7 +2296,6 @@
 	int died;
 #ifdef CONFIG_SSI
 	struct vproc *vp;
-	int hold_movement = 0;
 #endif
 
 	if (dentry->d_name.len == 4 && !memcmp(dentry->d_name.name,"self",4)) {
@@ -2407,25 +2322,8 @@
 	if (!vp)
 		goto out;
 
-	/*
-	 * If pid is migrating in then skip unhash, avoid deadlocking
-	 * the pvpop since it needs to grab the movement lock
-	 */
-	if (!vproc_migrating(vp)) {
-		VPROC_HOLD_MOVEMENT(vp, "proc_pid_lookup");
-		hold_movement = 1;
-	}
-
-#ifdef VPROC_HOLD_ZERO_GET_TASK
-	if (PVP(vp)->pvp_flag & PV_IS_LOCAL) {
-		task = PVP(vp)->pvp_pproc;
-		get_task_struct(task);
-	} else { /* remote process */
-		task = NULL;
-#else
 	task = proc_ssi_task(vp);
-	if( task == NULL ) { /* remote process */
-#endif /* !VPROC_HOLD_ZERO_GET_TASK */
+	if (task == NULL) { /* remote process */
 #ifdef TASK_HOLD_VPROC
 		if ((current->p_vproc && PVP(current->p_vproc)->pvp_localview == 1) ||
 		    (!PIDNODE(tgid) && tgid != 1)) {
@@ -2441,20 +2339,15 @@
 			  * It should have a task_struct.Otherwise it is
 			  * a non existent tgid
 			  */
-			if (hold_movement)
-				VPROC_RELEASE_MOVEMENT(vp, "proc_pid_lookup");
 			VPROC_RELE(vp, "proc_pid_lookup");
 			goto out;
 		 }
 	}
 
 	inode = proc_pid_make_inode(dir->i_sb, vp, PROC_TGID_INO, NULL);
-
-	if (!inode ) {
+	if (!inode) {
 		if (task)
 			put_task_struct(task);
-		if (hold_movement)
-			VPROC_RELEASE_MOVEMENT(vp, "proc_pid_lookup");
 		VPROC_RELE(vp, "proc_pid_lookup");
 		goto out;
 
@@ -2475,7 +2368,7 @@
 		put_task_struct(task);
 		goto out;
 	}
-#endif
+#endif /* !CONFIG_SSI */
 	inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
 	inode->i_op = &proc_tgid_base_inode_operations;
 	inode->i_fop = &proc_tgid_base_operations;
@@ -2505,8 +2398,6 @@
 	put_task_struct(task);
 #ifdef CONFIG_SSI
 	}
-	if (hold_movement)
-		VPROC_RELEASE_MOVEMENT(vp, "proc_pid_lookup");
 	VPROC_RELE(vp, "proc_pid_lookup");
 #endif /* CONFIG_SSI */
 	if (died) {
@@ -2521,10 +2412,8 @@
 /* SMP-safe */
 static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry, struct nameidata *nd)
 {
-#ifndef VPROC_HOLD_ZERO_GET_TASK
-	struct task_struct *task;
-#endif
 #ifndef CONFIG_SSI
+	struct task_struct *task;
 	struct task_struct *leader = proc_task(dir);
 #endif
 	struct inode *inode;
@@ -2543,20 +2432,7 @@
 	if (!vp)
 		goto out;
 
-	VPROC_HOLD_MOVEMENT(vp, "proc_task_lookup");
-#ifdef VPROC_HOLD_ZERO_GET_TASK
-	if (PVP(vp)->pvp_flag & PV_IS_LOCAL) {
-		/* leader's pid should be this vproc tgid */
-		if (leader->vp_pid != PVP(vp)->pvp_pproc->tgid) {
-			VPROC_RELEASE_MOVEMENT(vp, "proc_task_lookup");
-			VPROC_RELE(vp, "proc_task_lookup");
-			goto out;
-		}
-	} else { /* remote process */
-#else
-	task = proc_ssi_task(vp);
-	if( task == NULL ) { /* remote process */
-#endif /* !VPROC_HOLD_ZERO_GET_TASK */
+	if (!(PVP(vp)->pvp_flag & PV_IS_LOCAL)) {
 		 if (PVP(current->p_vproc)->pvp_localview == 1 ||
 				 ( !PIDNODE(tid) && (tid != 1) )) {
 			 /* 
@@ -2567,23 +2443,16 @@
 			  * It should have a task_struct.Otherwise it is
 			  * a non existent tid
 			  */
-			VPROC_RELEASE_MOVEMENT(vp, "proc_task_lookup");
 			VPROC_RELE(vp, "proc_task_lookup");
 			goto out;
 		 }
 	}
 
 	inode = proc_pid_make_inode(dir->i_sb, vp, PROC_TID_INO, &tgid);
-
-	VPROC_RELEASE_MOVEMENT(vp, "proc_task_lookup");
 	VPROC_RELE(vp, "proc_task_lookup");
 
 	/* leader's pid should be this vproc tgid */
-#ifdef VPROC_HOLD_ZERO_GET_TASK
 	if (!inode || leader->vp_pid != tgid) {
-#else
-	if (!inode || (!task && leader->vp_pid != tgid)) {
-#endif
 #ifdef PROC_TASK_LOOKUP_FIX
 		/* [ ssic-linux-Bugs-1938520 ]
 		 * Any attempt to do stat ("/proc/pid1/task/pid2") where pid2
@@ -2592,20 +2461,10 @@
 		 */
 		if (inode)
 			iput(inode);
-#ifndef VPROC_HOLD_ZERO_GET_TASK
-		if (task)
-			put_task_struct(task);
-#endif
-		goto out;
-#else
-#ifdef VPROC_HOLD_ZERO_GET_TASK
-		goto out;
-#else
-		goto out_drop_task;
-#endif
 #endif /* !PROC_TASK_LOOKUP_FIX */
+		goto out;
 	}
-#else /* !CONFIG_SSI */
+#else /* CONFIG_SSI */
 
 
 	read_lock(&tasklist_lock);
@@ -2634,12 +2493,7 @@
 
 	d_add(dentry, inode);
 
-#ifdef CONFIG_SSI
-#ifndef VPROC_HOLD_ZERO_GET_TASK
-	if( task )
-		put_task_struct(task);
-#endif
-#else
+#ifndef CONFIG_SSI
 	put_task_struct(task);
 #endif /* !CONFIG_SSI */
 	return NULL;
@@ -2823,10 +2677,8 @@
 
 #ifdef CONFIG_SSI
 	struct vproc *vp = proc_vproc(inode);
-#ifndef VPROC_HOLD_ZERO_GET_TASK
-	task_t *task = NULL;
-#endif
-	u_int *tids = NULL;
+	u_int *tids = tid_array;
+	int len = PROC_MAXPIDS;
 
 	/* SSI: we skip possible remote pid_alive() check here */
 #if 0
@@ -2855,34 +2707,7 @@
 	}
 
 #ifdef CONFIG_SSI
-	VPROC_HOLD_MOVEMENT(vp, "proc_task_readdir");
-#ifndef VPROC_HOLD_ZERO_GET_TASK
-	task = proc_ssi_task(vp);
-	if ( !PVP(current->p_vproc)->pvp_localview || !task) {
-#else
-	if (!(PVP(vp)->pvp_flag & PV_IS_LOCAL)) {
-#endif
-		int len = PROC_MAXPIDS;
-		/*
-		 * remote listing
-		 */
-		/* VPROC_HOLD(vp, "proc_task_readdir"); */
-		tids = tid_array;
-		nr_tids = PVPOP_PROCFS_TID_LIST(vp, pos, &tids, &len);
-		/* VPROC_RELE(vp, "proc_task_readdir"); */
-	} else {
-#ifdef TASK_HOLD_VPROC
-		if (!PV_IS_ALIVE(PVP(vp))) {
-			VPROC_RELEASE_MOVEMENT(vp, "proc_task_readdir");
-			goto out;
-		}
-#endif
-		nr_tids = get_tid_list(pos, tid_array, inode);
-#ifndef VPROC_HOLD_ZERO_GET_TASK
-		put_task_struct(task);
-#endif
-	}
-	VPROC_RELEASE_MOVEMENT(vp, "proc_task_readdir");
+	nr_tids = PVPOP_PROCFS_TID_LIST(vp, pos, &tids, &len);
 #else
 	nr_tids = get_tid_list(pos, tid_array, inode);
 #endif /* !CONFIG_SSI */
@@ -3114,27 +2939,23 @@
 }
 
 #ifdef TASK_HOLD_VPROC
-/* TODO: use PVPOP_MIGRATE */
 int
 vproc_migrate_local(struct vproc *v, clusternode_t node)
 {
-	struct pvproc *pvp = PVP(v);
-	int ret;
-
-	if (!PV_IS_ALIVE(pvp) || (pvp->pvp_flag & PV_EXITING))
-		return -EINVAL;
-
-	ret = VPROC_HOLD_MOVEMENT_LOCAL(v, "vproc_migrate_local");
-	if (ret == -EREMOTE)
-		return ret;
-	SSI_ASSERT(ret == ESUCCESS);
+	task_t *task;
+	int ret = -EINVAL;
 
-	if (PV_IS_ALIVE(pvp) && !(pvp->pvp_pproc->flags & PF_EXITING)) {
-		(void) setup_execnode_move(pvp->pvp_pproc, node, MOV_SIGMIG);
-	} else
-		ret = -EINVAL;
+	task = proc_ssi_task(v);
+	if (!task)
+		return -EREMOTE;
+	if ((task->flags & PF_EXITING) || !pid_alive(task))
+		goto out;
 
-	VPROC_RELEASE_MOVEMENT(v, "vproc_migrate_local");
+	ret = setup_execnode_move(task, node, MOV_SIGMIG);
+	if (ret > 0)
+		ret = 0;
+out:
+	put_task_struct(task);
 	return ret;
 }
 


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