On Wed, 29 May 2013 12:26:25 -0500
Serge Hallyn <serge.hal...@ubuntu.com> wrote:
> 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>
Acked-by: Dwight Engen <dwight.en...@oracle.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;
> }
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