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From: Serge E. Hallyn on 29 Jul 2010 16:00
The actual code does not detect 'all' with one subsystem name, which
is IMHO mutually exclusive and when an option is specified even if it
is not a subsystem name, we have to specify the 'all' option with the
other option.
eg:
not detected : mount -t cgroup -o all,freezer cgroup /cgroup
not flexible : mount -t cgroup -o noprefix,all cgroup /cgroup

This patch fix this and makes the code a bit more clear by replacing
'else if' indentation by 'continue' blocks in the loop.

Signed-off-by: Daniel Lezcano <daniel.lezcano(a)free.fr>
Signed-off-by: Serge E. Hallyn <serge.hallyn(a)canonical.com>
Cc: Eric W. Biederman <ebiederm(a)xmission.com>
Cc: Paul Menage <menage(a)google.com>
---
kernel/cgroup.c | 91 +++++++++++++++++++++++++++++++++++++------------------
1 files changed, 61 insertions(+), 30 deletions(-)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index dfbff78..09fb6f9 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1074,7 +1074,8 @@ struct cgroup_sb_opts {
*/
static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
{
- char *token, *o = data ?: "all";
+ char *token, *o = data;
+ bool all_ss = false, one_ss = false;
unsigned long mask = (unsigned long)-1;
int i;
bool module_pin_failed = false;
@@ -1088,26 +1089,30 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
memset(opts, 0, sizeof(*opts));

while ((token = strsep(&o, ",")) != NULL) {
+
if (!*token)
return -EINVAL;
- if (!strcmp(token, "all")) {
- /* Add all non-disabled subsystems */
- opts->subsys_bits = 0;
- for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
- struct cgroup_subsys *ss = subsys[i];
- if (ss == NULL)
- continue;
- if (!ss->disabled)
- opts->subsys_bits |= 1ul << i;
- }
- } else if (!strcmp(token, "none")) {
+ if (!strcmp(token, "none")) {
/* Explicitly have no subsystems */
opts->none = true;
- } else if (!strcmp(token, "noprefix")) {
+ continue;
+ }
+ if (!strcmp(token, "all")) {
+ /* Mutually exclusive option 'all' + subsystem name */
+ if (one_ss)
+ return -EINVAL;
+ all_ss = true;
+ continue;
+ }
+ if (!strcmp(token, "noprefix")) {
set_bit(ROOT_NOPREFIX, &opts->flags);
- } else if (!strcmp(token, "clone_children")) {
+ continue;
+ }
+ if (!strcmp(token, "clone_children")) {
set_bit(ROOT_CLONE_CHILDREN, &opts->flags);
- } else if (!strncmp(token, "release_agent=", 14)) {
+ continue;
+ }
+ if (!strncmp(token, "release_agent=", 14)) {
/* Specifying two release agents is forbidden */
if (opts->release_agent)
return -EINVAL;
@@ -1115,7 +1120,9 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
kstrndup(token + 14, PATH_MAX, GFP_KERNEL);
if (!opts->release_agent)
return -ENOMEM;
- } else if (!strncmp(token, "name=", 5)) {
+ continue;
+ }
+ if (!strncmp(token, "name=", 5)) {
const char *name = token + 5;
/* Can't specify an empty name */
if (!strlen(name))
@@ -1137,20 +1144,44 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
GFP_KERNEL);
if (!opts->name)
return -ENOMEM;
- } else {
- struct cgroup_subsys *ss;
- for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
- ss = subsys[i];
- if (ss == NULL)
- continue;
- if (!strcmp(token, ss->name)) {
- if (!ss->disabled)
- set_bit(i, &opts->subsys_bits);
- break;
- }
- }
- if (i == CGROUP_SUBSYS_COUNT)
- return -ENOENT;
+
+ continue;
+ }
+
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
+ struct cgroup_subsys *ss = subsys[i];
+ if (ss == NULL)
+ continue;
+ if (strcmp(token, ss->name))
+ continue;
+ if (ss->disabled)
+ continue;
+
+ /* Mutually exclusive option 'all' + subsystem name */
+ if (all_ss)
+ return -EINVAL;
+ set_bit(i, &opts->subsys_bits);
+ one_ss = true;
+
+ break;
+ }
+ if (i == CGROUP_SUBSYS_COUNT)
+ return -ENOENT;
+ }
+
+ /*
+ * If the 'all' option was specified select all the subsystems,
+ * 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)) {
+ for (i = 0; i < CGROUP_SUBSYS_COUNT; i++) {
+ struct cgroup_subsys *ss = subsys[i];
+ if (ss == NULL)
+ continue;
+ if (ss->disabled)
+ continue;
+ set_bit(i, &opts->subsys_bits);
}
}

--
1.7.0.4

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Prev: [PATCH 01/17] memblock: Add memblock_free/reserve_reserved_regions()
Next: [PATCH 1/3] cgroup : add clone_children control file