Those go through commands.c and are already mutex'ed that way.
Also remove a unmatched container_disk_unlock in lxcapi_create.
Since is_stopped uses getstate which is no longer locked, rename
it to drop the _locked suffix.
And convert save_config to taking the disk lock. This way the
save_ and load_config are mutexing each other, as they should.
Changelog: May 29:
Per Dwight's comment, take the lock before opening the config
FILE *.
Only take disklock at load and save_config when we're using the
container's config file, not when read/writing from/to another
file.
Signed-off-by: Serge Hallyn <serge.hal...@ubuntu.com>
---
src/lxc/lxccontainer.c | 92 +++++++++++++++++++++++++++++++++-----------------
1 file changed, 61 insertions(+), 31 deletions(-)
diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
index b34b8e8..ef95033 100644
--- a/src/lxc/lxccontainer.c
+++ b/src/lxc/lxccontainer.c
@@ -287,21 +287,15 @@ out:
static const char *lxcapi_state(struct lxc_container *c)
{
- const char *ret;
lxc_state_t s;
if (!c)
return NULL;
- if (container_disk_lock(c))
- return NULL;
s = lxc_getstate(c->name, c->config_path);
- ret = lxc_state2str(s);
- container_disk_unlock(c);
-
- return ret;
+ return lxc_state2str(s);
}
-static bool is_stopped_locked(struct lxc_container *c)
+static bool is_stopped(struct lxc_container *c)
{
lxc_state_t s;
s = lxc_getstate(c->name, c->config_path);
@@ -326,10 +320,7 @@ static bool lxcapi_freeze(struct lxc_container *c)
if (!c)
return false;
- if (container_disk_lock(c))
- return false;
ret = lxc_freeze(c->name, c->config_path);
- container_disk_unlock(c);
if (ret)
return false;
return true;
@@ -341,10 +332,7 @@ static bool lxcapi_unfreeze(struct lxc_container *c)
if (!c)
return false;
- if (container_disk_lock(c))
- return false;
ret = lxc_unfreeze(c->name, c->config_path);
- container_disk_unlock(c);
if (ret)
return false;
return true;
@@ -369,7 +357,8 @@ static bool load_config_locked(struct lxc_container *c,
const char *fname)
static bool lxcapi_load_config(struct lxc_container *c, const char *alt_file)
{
- bool ret = false;
+ bool ret = false, need_disklock = false;
+ int lret;
const char *fname;
if (!c)
return false;
@@ -379,10 +368,27 @@ static bool lxcapi_load_config(struct lxc_container *c,
const char *alt_file)
fname = alt_file;
if (!fname)
return false;
- if (container_disk_lock(c))
+ /*
+ * If we're reading something other than the container's config,
+ * we only need to lock the in-memory container. If loading the
+ * container's config file, take the disk lock.
+ */
+ if (strcmp(fname, c->configfile) == 0)
+ need_disklock = true;
+
+ if (need_disklock)
+ lret = container_disk_lock(c);
+ else
+ lret = container_mem_lock(c);
+ if (lret)
return false;
+
ret = load_config_locked(c, fname);
- container_disk_unlock(c);
+
+ if (need_disklock)
+ container_disk_unlock(c);
+ else
+ container_mem_unlock(c);
return ret;
}
@@ -888,7 +894,6 @@ static bool lxcapi_create(struct lxc_container *c, const
char *t,
out_unlock:
if (partial_fd >= 0)
remove_partial(c, partial_fd);
- container_disk_unlock(c);
out:
if (tpath)
free(tpath);
@@ -1143,30 +1148,55 @@ static int lxcapi_get_keys(struct lxc_container *c,
const char *key, char *retv,
#define LXC_DEFAULT_CONFIG "/etc/lxc/default.conf"
static bool lxcapi_save_config(struct lxc_container *c, const char *alt_file)
{
+ FILE *fout;
+ bool ret = false, need_disklock = false;
+ int lret;
+
if (!alt_file)
alt_file = c->configfile;
if (!alt_file)
return false; // should we write to stdout if no file is
specified?
- if (!c->lxc_conf)
+
+ // If we haven't yet loaded a config, load the stock config
+ if (!c->lxc_conf) {
if (!c->load_config(c, LXC_DEFAULT_CONFIG)) {
ERROR("Error loading default configuration file %s
while saving %s\n", LXC_DEFAULT_CONFIG, c->name);
return false;
}
+ }
if (!create_container_dir(c))
return false;
- FILE *fout = fopen(alt_file, "w");
- if (!fout)
- return false;
- if (container_mem_lock(c)) {
- fclose(fout);
+ /*
+ * If we're writing to the container's config file, take the
+ * disk lock. Otherwise just take the memlock to protect the
+ * struct lxc_container while we're traversing it.
+ */
+ if (strcmp(c->configfile, alt_file) == 0)
+ need_disklock = true;
+
+ if (need_disklock)
+ lret = container_disk_lock(c);
+ else
+ lret = container_mem_lock(c);
+
+ if (lret)
return false;
- }
+
+ fout = fopen(alt_file, "w");
+ if (!fout)
+ goto out;
write_config(fout, c->lxc_conf);
fclose(fout);
- container_mem_unlock(c);
- return true;
+ ret = true;
+
+out:
+ if (need_disklock)
+ container_disk_unlock(c);
+ else
+ container_mem_unlock(c);
+ return ret;
}
// do we want the api to support --force, or leave that to the caller?
@@ -1185,7 +1215,7 @@ static bool lxcapi_destroy(struct lxc_container *c)
return false;
}
- if (!is_stopped_locked(c)) {
+ if (!is_stopped(c)) {
// we should queue some sort of error - in c->error_string?
ERROR("container %s is not stopped", c->name);
goto out;
@@ -1342,7 +1372,7 @@ static bool lxcapi_set_cgroup_item(struct lxc_container
*c, const char *subsys,
if (container_mem_lock(c))
return false;
- if (is_stopped_locked(c))
+ if (is_stopped(c))
goto err;
ret = lxc_cgroup_set(c->name, subsys, value, c->config_path);
@@ -1363,7 +1393,7 @@ static int lxcapi_get_cgroup_item(struct lxc_container
*c, const char *subsys, c
if (container_mem_lock(c))
return -1;
- if (is_stopped_locked(c))
+ if (is_stopped(c))
goto out;
ret = lxc_cgroup_get(c->name, subsys, retv, inlen, c->config_path);
@@ -1827,7 +1857,7 @@ struct lxc_container *lxcapi_clone(struct lxc_container
*c, const char *newname,
if (container_mem_lock(c))
return NULL;
- if (!is_stopped_locked(c)) {
+ if (!is_stopped(c)) {
ERROR("error: Original container (%s) is running", c->name);
goto out;
}
--
1.8.1.2
------------------------------------------------------------------------------
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