[SSI] openssi/kernel/cluster/ssi/cfs cfs_ipcshm.c,1.20,1.21

Update of /cvsroot/ssic-linux/openssi/kernel/cluster/ssi/cfs
In directory fdv4jf1.ch3.sourceforge.com:/tmp/cvs-serv32639/cluster/ssi/cfs

Modified Files:
      Tag: OPENSSI-FC
	cfs_ipcshm.c 
Log Message:
IPC:
- Fix shm_ids_svr table race; mutex not held, wrong mutex held, or releasing unheld mutex. (#ifdef IPC_SHM_RACE_FIX)
- Downgrade NSC_IPC_WRLOCK() where appropriate; reduce contention. (#ifdef NSC_IPC_RWLOCK_DOWNGRADE)

 cluster/ssi/cfs/cfs_ipcshm.c   |   66 +++++++++++++++++++++++++++++------
 cluster/ssi/ipc/ipcshm_svr.c   |   76 ++++++++++++++++++++++++++++++++++-------
 cluster/ssi/ipc/namesvr_func.c |   68 ++++++++++++++++++++++++++++++++++++
 include/linux/config.h         |    1 
 ipc/shm.c                      |    3 +
 5 files changed, 188 insertions(+), 26 deletions(-)


Index: cfs_ipcshm.c
===================================================================
RCS file: /cvsroot/ssic-linux/openssi/kernel/cluster/ssi/cfs/cfs_ipcshm.c,v
retrieving revision 1.20
retrieving revision 1.21
diff -u -d -r1.20 -r1.21
--- cfs_ipcshm.c	19 Feb 2009 08:01:01 -0000	1.20
+++ cfs_ipcshm.c	24 Feb 2009 01:51:47 -0000	1.21
@@ -43,6 +43,11 @@
 
 extern struct super_block *cfs_shm_sb;
 extern struct vfsmount *shm_mnt;
+#ifdef IPC_SHM_RACE_FIX
+extern struct ipc_ids shm_ids_svr;
+extern void ipc_drop_locks(int, struct kern_ipc_perm *, struct ipc_ids *, int);
+extern struct kern_ipc_perm * ipc_get_locks(int, struct ipc_ids *, int);
+#endif
 static struct super_block *shm_get_cfs_sb(clusternode_t, struct vfsmount *);
 
 struct super_block *cfs_shm_sb;
@@ -80,6 +85,7 @@
 	svr_shm->shm_id = newid;
 	svr_shm->shm_segsz = size;
 	svr_shm->shm_cprid = current->pid;
+
 	svr_shm->shm_perm.key = key;
 	svr_shm->shm_perm.local_view = ssi_get_localview();
 	svr_shm->shm_perm.mode = (shmflg & S_IRWXUGO);
@@ -88,6 +94,8 @@
 	svr_shm->shm_perm.gid = current->egid;
 	svr_shm->shm_perm.cgid = current->egid;
 	svr_shm->shm_perm.seq = shp->shm_perm.seq;
+	/* shm_unlock(svr_shm); */
+
 	nl = NSC_NODELIST_ALLOC();
 	NSC_NODELIST_SET1(nl, this_node);
 	svr_shm->shm_nodelist = nl;
@@ -124,15 +132,33 @@
 			de = dget(shmsvr->shm_file->f_dentry);
 			return de;
 		}
+#ifdef IPC_SHM_RACE_FIX
+		ipc_get_locks(0, &shm_ids_svr, 1);
+#endif
 		shmsvr = (struct shmid_kernel_svr *)shm_svr_get(newid);
-		if (!shmsvr)
+		if (!shmsvr) {
+#ifdef IPC_SHM_RACE_FIX
+			ipc_drop_locks(0, NULL, &shm_ids_svr, 1);
+#endif
 			return NULL;
+		}
 		ip = cfs_hpget(cfs_shm_sb, shmsvr->shm_svr);
-		if (ip == NULL)
+		if (ip == NULL) {
+#ifdef IPC_SHM_RACE_FIX
+			ipc_drop_locks(0, NULL, &shm_ids_svr, 1);
+#endif
 			return NULL;
+		}
 		memcpy(&this, &(shmsvr->shm_svr->sct_dp->d_name), sizeof(struct qstr));
+#ifdef IPC_SHM_RACE_FIX
+		ipc_drop_locks(0, NULL, &shm_ids_svr, 1);
+#endif
 		de = d_alloc(cfs_shm_sb->s_root, &this);
 #ifdef CFS_IPCSHM_DENTRY
+		if (!de) {
+			iput(ip);
+			return NULL;
+		}
 		d_add(de, ip);
 #else
 		de->d_sb = ip->i_sb;
@@ -195,11 +221,16 @@
 				return NULL;
 
 			de = d_alloc(cfs_node_sb->s_root, &this);
-			ip->i_size = size;
-#ifndef CFS_IPCSHM_DENTRY
+#ifdef CFS_IPCSHM_DENTRY
+			if (!de) {
+				iput(ip);
+				return NULL;
+			}
+#else
 			de->d_sb = ip->i_sb;
 			de->d_parent = cfs_node_sb->s_root;
 #endif
+			ip->i_size = size;
 			d_instantiate(de, ip);
 #ifdef JUNK
 			shp->shm_file->f_dentry = de;
@@ -274,6 +305,7 @@
 	HASH_RELE(shmsvr->shm_svr);
 }
 
+/* Caller must hold shm_ids.sem or shm_ids_svr.sem */
 struct inode *
 shm_svr_get_inode(int id)
 {
@@ -300,9 +332,19 @@
 	sscanf(dentry->d_name.name, "SYSV%x", &real_key);
 	cli_ipcname_getid(NAME_SERVICE_SHM, real_key, 0, &id, &svr, 
 						ssi_get_localview(), &size);
+#ifdef IPC_SHM_RACE_FIX
+	ipc_get_locks(0, &shm_ids_svr, 1);
+#endif
 	inode = shm_svr_get_inode(id);
-	if (!inode || !igrab(inode))
+	if (!inode || !igrab(inode)) {
+#ifdef IPC_SHM_RACE_FIX
+		ipc_drop_locks(0, NULL, &shm_ids_svr, 1);
+#endif
 		return ERR_PTR(-EACCES);
+	}
+#ifdef IPC_SHM_RACE_FIX
+	ipc_drop_locks(0, NULL, &shm_ids_svr, 1);
+#endif
 
 	return d_splice_alias(inode, dentry);
 }
@@ -313,16 +355,16 @@
 	int i;
 
 	if (!strncmp(de->d_name.name, "SYSV", 4)) {
-		if (is_pfs && de->d_inode && is_shmem_inode(de->d_inode))
-			return 1;
-
+		if (is_pfs) {
+			if (de->d_inode)
+				return is_shmem_inode(de->d_inode);
+			/* negative lookup */
+			return (de->d_sb == (cfs_shm_node_mnts[this_node])->mnt_root->d_sb);
+		}
 		for (i=1; i <= (NSC_MAX_NODE_VALUE + 1); i++) {
 			if (!cfs_shm_node_mnts[i])
 				continue;
-			if (is_pfs) { /* negative lookup */
-				if (de->d_sb == (cfs_shm_node_mnts[i])->mnt_root->d_sb)
-					return 1;
-			} else if (de->d_sb == (cfs_shm_node_mnts[i])->mnt_sb)
+			if (de->d_sb == (cfs_shm_node_mnts[i])->mnt_sb)
 				return 1;
 		}
 	}


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