Any loaded configurations must be correctly unloaded on coresight module exit, or issues can arise with nested locking in the configfs directory code if built with CONFIG_LOCKDEP.
Prior to this patch, the preloaded configuration configfs directory entries were being unloaded by the recursive code in configfs_unregister_subsystem().
However, when built with CONFIG_LOCKDEP, this caused a nested lock warning, which was not mitigated by the LOCKDEP dependent code in fs/configfs/dir.c designed to prevent this, due to the different directory levels for the root of the directory being removed.
As the preloaded (and all other) configurations are registered after configfs_register_subsystem(), we now explicitly unload them before the call to configfs_unregister_subsystem().
The new routine cscfg_unload_cfgs_on_exit() iterates through the load owner list to unload any remaining configurations that were not unloaded by the user before the module exits. This covers both the CSCFG_OWNER_PRELOAD and CSCFG_OWNER_MODULE owner types, and will be extended to cover future load owner types for CoreSight configurations.
Applies to coresight/next
Fixes: eb2ec49606c2 ("coresight: syscfg: Update load API for config loadable modules") Reported-by: Suzuki Poulose suzuki.poulose@arm.com Signed-off-by: Mike Leach mike.leach@linaro.org --- .../hwtracing/coresight/coresight-syscfg.c | 57 +++++++++++++++++-- 1 file changed, 52 insertions(+), 5 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c index 11850fd8c3b5..75df0f865355 100644 --- a/drivers/hwtracing/coresight/coresight-syscfg.c +++ b/drivers/hwtracing/coresight/coresight-syscfg.c @@ -1056,14 +1056,61 @@ static int cscfg_create_device(void) return err; }
-static void cscfg_clear_device(void) +/* + * Loading and unloading is generally on user discretion. + * If exiting due to coresight module unload, we need to unload any configurations that remain, + * before we unregister the configfs intrastructure. + * + * Do this by walking the load_owner list and taking appropriate action, depending on the load + * owner type. + * + * called with the cscfg_mutex held + */ + +#define LOADABLE_MOD_ERR "cscfg: ERROR - a loadable module failed to unload configs on exit\n" + +static void cscfg_unload_cfgs_on_exit(void) { - struct cscfg_config_desc *cfg_desc; + struct cscfg_load_owner_info *owner_info = NULL;
- mutex_lock(&cscfg_mutex); - list_for_each_entry(cfg_desc, &cscfg_mgr->config_desc_list, item) { - etm_perf_del_symlink_cscfg(cfg_desc); + while (!list_empty(&cscfg_mgr->load_order_list)) { + + /* remove in reverse order of loading */ + owner_info = list_last_entry(&cscfg_mgr->load_order_list, + struct cscfg_load_owner_info, item); + + /* action according to type */ + switch (owner_info->type) { + case CSCFG_OWNER_PRELOAD: + /* + * preloaded descriptors are statically allocated in + * this module - just need to unload dynamic items from + * csdev lists, and remove from configfs directories. + */ + pr_info("cscfg: unloading preloaded configurations\n"); + cscfg_unload_owned_cfgs_feats(owner_info); + break; + + case CSCFG_OWNER_MODULE: + /* + * this is an error - the loadable module must have been unloaded prior + * to the coresight module unload. Therefore that module has not + * correctly unloaded configs in its own exit code. + * Nothing to do other than emit an error string. + */ + pr_err(LOADABLE_MOD_ERR); + break; + } + + /* remove from load order list */ + list_del(&owner_info->item); } +} + +static void cscfg_clear_device(void) +{ + mutex_lock(&cscfg_mutex); + cscfg_unload_cfgs_on_exit(); cscfg_configfs_release(cscfg_mgr); device_unregister(cscfg_device()); mutex_unlock(&cscfg_mutex);