procfs: retrieve both RS tables from RS at once

Previously, procfs would retrieve the rproc and rprocpub tables from
RS in two separate calls.  This allowed for a race condition where the
tables could change in between the calls, resulting in a panic in
procfs under certain circumstances.  RS now implements a new method
for getsysinfo that allows the retrieval of both tables at once.

Change-Id: I5ec22d25898361270c90e805a43fc6d76ad9e29d

minix/fs/procfs/service.c

@@ -19,8 +19,11 @@ struct policies {
 	enum policy supported;
 };
 
-static struct rprocpub rprocpub[NR_SYS_PROCS];
+static struct {
-static struct rproc rproc[NR_SYS_PROCS];
+	struct rproc proc[NR_SYS_PROCS];
+	struct rprocpub pub[NR_SYS_PROCS];
+} rproc;
+
 static struct policies policies[NR_SYS_PROCS];
 
 static struct inode *service_node;
@@ -132,9 +135,9 @@ service_get_policies(struct policies * pol, index_t slot)
 	};
 
 	/* Find the related policy, based on the file name of the service. */
-	ref_label = strrchr(rprocpub[slot].proc_name, '/');
+	ref_label = strrchr(rproc.pub[slot].proc_name, '/');
 	if (NULL == ref_label)
-		ref_label = rprocpub[slot].proc_name;
+		ref_label = rproc.pub[slot].proc_name;
 
 	memset(pol[slot].formatted, 0, MAX_POL_FORMAT_SZ);
 	for(pos = 0; pos < (sizeof(def_pol) / sizeof(def_pol[0])); pos++) {
@@ -161,11 +164,15 @@ service_update(void)
 	struct inode *node;
 	struct inode_stat stat;
 	index_t slot;
+	static int warned = FALSE;
+	int r;
 
-	/* There is not much we can do if either of these calls fails. */
+	/* There is not much we can do if this call fails. */
-	(void)getsysinfo(RS_PROC_NR, SI_PROCPUB_TAB, rprocpub,
+	r = getsysinfo(RS_PROC_NR, SI_PROCALL_TAB, &rproc, sizeof(rproc));
-	    sizeof(rprocpub));
+	if (r != OK && !warned) {
-	(void)getsysinfo(RS_PROC_NR, SI_PROC_TAB, rproc, sizeof(rproc));
+		printf("PROCFS: unable to obtain RS tables (%d)\n", r);
+		warned = TRUE;
+	}
 
 	/*
 	 * As with PIDs, we make two passes.  Delete first, then add.  This
@@ -180,8 +187,8 @@ service_update(void)
 		 * If the slot is no longer in use, or the label name does not
 		 * match, the node must be deleted.
 		 */
-		if (!(rproc[slot].r_flags & RS_IN_USE) ||
+		if (!(rproc.proc[slot].r_flags & RS_IN_USE) ||
-		    strcmp(get_inode_name(node), rprocpub[slot].label))
+		    strcmp(get_inode_name(node), rproc.pub[slot].label))
 			delete_inode(node);
 	}
 
@@ -191,11 +198,11 @@ service_update(void)
 	stat.gid = SUPER_USER;
 
 	for (slot = 0; slot < NR_SYS_PROCS; slot++) {
-		if (!(rproc[slot].r_flags & RS_IN_USE) ||
+		if (!(rproc.proc[slot].r_flags & RS_IN_USE) ||
 		    get_inode_by_index(service_node, slot) != NULL)
 			continue;
 
-		node = add_inode(service_node, rprocpub[slot].label, slot,
+		node = add_inode(service_node, rproc.pub[slot].label, slot,
 		    &stat, (index_t)0, (cbdata_t)slot);
 
 		if (node == NULL)
@@ -277,8 +284,8 @@ service_read(struct inode * node)
 		return;
 
 	slot = get_inode_index(node);
-	rpub = &rprocpub[slot];
+	rpub = &rproc.pub[slot];
-	rp = &rproc[slot];
+	rp = &rproc.proc[slot];
 
 	/* TODO: add a large number of other fields! */
 	buf_printf("filename: %s\n", rpub->proc_name);

minix/include/minix/sysinfo.h

@@ -13,6 +13,7 @@ int getsysinfo(endpoint_t who, int what, void *where, size_t size);
 #define SI_DATA_STORE	   5	/* get copy of data store mappings */
 #define SI_CALL_STATS	   9	/* system call statistics */
 #define SI_PROCPUB_TAB	   11	/* copy of public entries of process table */
+#define SI_PROCALL_TAB	   12	/* copy of both private and public entries */
 
 #endif
 

minix/servers/rs/request.c

@@ -867,18 +867,33 @@ message *m_ptr;
 {
   vir_bytes src_addr, dst_addr;
   int dst_proc;
-  size_t len;
+  size_t size, len;
   int s;
 
   /* Check if the call can be allowed. */
   if((s = check_call_permission(m_ptr->m_source, 0, NULL)) != OK)
       return s;
 
+  dst_proc = m_ptr->m_source;
+  dst_addr = m_ptr->m_lsys_getsysinfo.where;
+  size = m_ptr->m_lsys_getsysinfo.size;
+
   switch(m_ptr->m_lsys_getsysinfo.what) {
   case SI_PROC_TAB:
   	src_addr = (vir_bytes) rproc;
   	len = sizeof(struct rproc) * NR_SYS_PROCS;
   	break; 
+  case SI_PROCALL_TAB:
+	/* Copy out both tables, one after the other. */
+	src_addr = (vir_bytes) rproc;
+	len = sizeof(struct rproc) * NR_SYS_PROCS;
+	if (len > size)
+		return EINVAL;
+	if ((s = sys_datacopy(SELF, src_addr, dst_proc, dst_addr, len)) != OK)
+		return s;
+	dst_addr += len;
+	size -= len;
+	/* FALLTHROUGH */
   case SI_PROCPUB_TAB:
   	src_addr = (vir_bytes) rprocpub;
   	len = sizeof(struct rprocpub) * NR_SYS_PROCS;
@@ -887,11 +902,9 @@ message *m_ptr;
   	return(EINVAL);
   }
 
-  if (len != m_ptr->m_lsys_getsysinfo.size)
+  if (len != size)
 	return(EINVAL);
 
-  dst_proc = m_ptr->m_source;
-  dst_addr = m_ptr->m_lsys_getsysinfo.where;
   return sys_datacopy(SELF, src_addr, dst_proc, dst_addr, len);
 }