| [PATCH 3/3] make 'none' field a flag [message #44486 is a reply to message #44484] | 
			Sun, 11 December 2011 14:45    | 
		 
		
			
				
				
				
					
						  
						Glauber Costa
						 Messages: 916 Registered: October 2011 
						
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					Senior Member  | 
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		There is no reason to have a flags field, and then a separate 
bool field just to indicate if 'none' subsystem were explicitly 
requested. 
 
Make it a flag 
 
Signed-off-by: Glauber Costa <glommer@parallels.com> 
--- 
 kernel/cgroup.c |   20 ++++++++++++-------- 
 1 files changed, 12 insertions(+), 8 deletions(-) 
 
diff --git a/kernel/cgroup.c b/kernel/cgroup.c 
index fa405ee..e700abe 100644 
--- a/kernel/cgroup.c 
+++ b/kernel/cgroup.c 
@@ -232,6 +232,7 @@ inline int cgroup_is_removed(const struct cgroup *cgrp) 
 enum { 
 	ROOT_NOPREFIX, /* mounted subsystems have no named prefix */ 
 	ROOT_CLONE_CHILDREN, /* mounted subsystems starts with clone_children */ 
+	ROOT_NOSUBSYS, /* explicitly asked for 'none' subsystems */ 
 }; 
  
 static int cgroup_is_releasable(const struct cgroup *cgrp) 
@@ -1064,13 +1065,16 @@ struct cgroup_sb_opts { 
 	unsigned long flags; 
 	char *release_agent; 
 	char *name; 
-	/* User explicitly requested empty subsystem */ 
-	bool none; 
  
 	struct cgroupfs_root *new_root; 
  
 }; 
  
+static inline int opts_no_subsys(const struct cgroup_sb_opts *opts) 
+{ 
+	return test_bit(ROOT_NOSUBSYS, &opts->flags); 
+} 
+ 
 /* 
  * Convert a hierarchy specifier into a bitmask of subsystems and flags. Call 
  * with cgroup_mutex held to protect the subsys[] array. This function takes 
@@ -1098,7 +1102,7 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) 
 			return -EINVAL; 
 		if (!strcmp(token, "none")) { 
 			/* Explicitly have no subsystems */ 
-			opts->none = true; 
+			set_bit(ROOT_NOSUBSYS, &opts->flags); 
 			continue; 
 		} 
 		if (!strcmp(token, "all")) { 
@@ -1178,7 +1182,7 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) 
 	 * otherwise 'all, 'none' and a subsystem name options were not 
 	 * specified, let's default to 'all' 
 	 */ 
-	if (all_ss || (!all_ss && !one_ss && !opts->none)) { 
+	if (all_ss || (!all_ss && !one_ss && !opts_no_subsys(opts))) { 
 		for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) { 
 			struct cgroup_subsys *ss = subsys[i]; 
 			if (ss == NULL) 
@@ -1202,7 +1206,7 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) 
  
  
 	/* Can't specify "none" and some subsystems */ 
-	if (opts->subsys_bits && opts->none) 
+	if (opts->subsys_bits && opts_no_subsys(opts)) 
 		return -EINVAL; 
  
 	/* 
@@ -1370,7 +1374,7 @@ static int cgroup_test_super(struct super_block *sb, void *data) 
 	 * If we asked for subsystems (or explicitly for no 
 	 * subsystems) then they must match 
 	 */ 
-	if ((opts->subsys_bits || opts->none) 
+	if ((opts->subsys_bits || opts_no_subsys(opts)) 
 	    && (opts->subsys_bits != root->subsys_bits)) 
 		return 0; 
  
@@ -1381,7 +1385,7 @@ static struct cgroupfs_root *cgroup_root_from_opts(struct cgroup_sb_opts *opts) 
 { 
 	struct cgroupfs_root *root; 
  
-	if (!opts->subsys_bits && !opts->none) 
+	if (!opts->subsys_bits && !opts_no_subsys(opts)) 
 		return NULL; 
  
 	root = kzalloc(sizeof(*root), GFP_KERNEL); 
@@ -1426,7 +1430,7 @@ static int cgroup_set_super(struct super_block *sb, void *data) 
 	if (!opts->new_root) 
 		return -EINVAL; 
  
-	BUG_ON(!opts->subsys_bits && !opts->none); 
+	BUG_ON(!opts->subsys_bits && !opts_no_subsys(opts)); 
  
 	ret = set_anon_super(sb, NULL); 
 	if (ret) 
--  
1.7.6.4
		
		
		
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