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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 /kernel/cgroup.c
parent8ca739e3694b83cdf22be0f6eff063e721deb1e4 (diff)
downloadlinux-f9ab5b5b0f5be506640321d710b0acd3dca6154a.tar.bz2
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>
Diffstat (limited to 'kernel/cgroup.c')
-rw-r--r--kernel/cgroup.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 3fb789f6df94..3737a682cdf5 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;