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authorLi Zefan <lizf@cn.fujitsu.com>2009-06-17 16:26:33 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-18 13:03:46 -0700
commitf9ab5b5b0f5be506640321d710b0acd3dca6154a (patch)
treeabd8e17febed8507b4c0f96a88d2711fccb31b2b
parent8ca739e3694b83cdf22be0f6eff063e721deb1e4 (diff)
cgroups: forbid noprefix if mounting more than just cpuset subsystem
The 'noprefix' option was introduced for backwards-compatibility of cpuset, but actually it can be used when mounting other subsystems. This results in possibility of name collision, and now the collision can really happen, because we have 'stat' file in both memory and cpuacct subsystem: # mount -t cgroup -o noprefix,memory,cpuacct xxx /mnt Cgroup will happily mount the 2 subsystems, but only 'stat' file of memory subsys can be seen. We don't want users to use nopreifx, and also want to avoid name collision, so we change to allow noprefix only if mounting just the cpuset subsystem. [akpm@linux-foundation.org: fix shift for cpuset_subsys_id >= 32] Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Paul Menage <menage@google.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Acked-by: Dhaval Giani <dhaval@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--kernel/cgroup.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 3fb789f6df9..3737a682cdf 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -843,6 +843,11 @@ static int parse_cgroupfs_options(char *data,
struct cgroup_sb_opts *opts)
{
char *token, *o = data ?: "all";
+ unsigned long mask = (unsigned long)-1;
+
+#ifdef CONFIG_CPUSETS
+ mask = ~(1UL << cpuset_subsys_id);
+#endif
opts->subsys_bits = 0;
opts->flags = 0;
@@ -887,6 +892,15 @@ static int parse_cgroupfs_options(char *data,
}
}
+ /*
+ * Option noprefix was introduced just for backward compatibility
+ * with the old cpuset, so we allow noprefix only if mounting just
+ * the cpuset subsystem.
+ */
+ if (test_bit(ROOT_NOPREFIX, &opts->flags) &&
+ (opts->subsys_bits & mask))
+ return -EINVAL;
+
/* We can't have an empty hierarchy */
if (!opts->subsys_bits)
return -EINVAL;