From: Peter Oberparleiter oberpar@linux.ibm.com
[ Upstream commit 9372a82892c2caa6bccab9a4081166fa769699f8 ]
Currently allocation and registration of s390dbf debug areas are tied together. As a result, a debug area cannot be unregistered and re-registered while any process has an associated debugfs file open.
Fix this by splitting alloc/release from register/unregister.
Signed-off-by: Peter Oberparleiter oberpar@linux.ibm.com Signed-off-by: Heiko Carstens hca@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/s390/kernel/debug.c | 102 +++++++++++++++++++++------------------ 1 file changed, 56 insertions(+), 46 deletions(-)
diff --git a/arch/s390/kernel/debug.c b/arch/s390/kernel/debug.c index 7184d55d87aa..b1aadc3ad065 100644 --- a/arch/s390/kernel/debug.c +++ b/arch/s390/kernel/debug.c @@ -327,24 +327,6 @@ static debug_info_t *debug_info_create(const char *name, int pages_per_area, goto out;
rc->mode = mode & ~S_IFMT; - - /* create root directory */ - rc->debugfs_root_entry = debugfs_create_dir(rc->name, - debug_debugfs_root_entry); - - /* append new element to linked list */ - if (!debug_area_first) { - /* first element in list */ - debug_area_first = rc; - rc->prev = NULL; - } else { - /* append element to end of list */ - debug_area_last->next = rc; - rc->prev = debug_area_last; - } - debug_area_last = rc; - rc->next = NULL; - refcount_set(&rc->ref_count, 1); out: return rc; @@ -404,27 +386,10 @@ static void debug_info_get(debug_info_t *db_info) */ static void debug_info_put(debug_info_t *db_info) { - int i; - if (!db_info) return; - if (refcount_dec_and_test(&db_info->ref_count)) { - for (i = 0; i < DEBUG_MAX_VIEWS; i++) { - if (!db_info->views[i]) - continue; - debugfs_remove(db_info->debugfs_entries[i]); - } - debugfs_remove(db_info->debugfs_root_entry); - if (db_info == debug_area_first) - debug_area_first = db_info->next; - if (db_info == debug_area_last) - debug_area_last = db_info->prev; - if (db_info->prev) - db_info->prev->next = db_info->next; - if (db_info->next) - db_info->next->prev = db_info->prev; + if (refcount_dec_and_test(&db_info->ref_count)) debug_info_free(db_info); - } }
/* @@ -648,6 +613,31 @@ static int debug_close(struct inode *inode, struct file *file) return 0; /* success */ }
+/* Create debugfs entries and add to internal list. */ +static void _debug_register(debug_info_t *id) +{ + /* create root directory */ + id->debugfs_root_entry = debugfs_create_dir(id->name, + debug_debugfs_root_entry); + + /* append new element to linked list */ + if (!debug_area_first) { + /* first element in list */ + debug_area_first = id; + id->prev = NULL; + } else { + /* append element to end of list */ + debug_area_last->next = id; + id->prev = debug_area_last; + } + debug_area_last = id; + id->next = NULL; + + debug_register_view(id, &debug_level_view); + debug_register_view(id, &debug_flush_view); + debug_register_view(id, &debug_pages_view); +} + /** * debug_register_mode() - creates and initializes debug area. * @@ -677,19 +667,16 @@ debug_info_t *debug_register_mode(const char *name, int pages_per_area, if ((uid != 0) || (gid != 0)) pr_warn("Root becomes the owner of all s390dbf files in sysfs\n"); BUG_ON(!initialized); - mutex_lock(&debug_mutex);
/* create new debug_info */ rc = debug_info_create(name, pages_per_area, nr_areas, buf_size, mode); - if (!rc) - goto out; - debug_register_view(rc, &debug_level_view); - debug_register_view(rc, &debug_flush_view); - debug_register_view(rc, &debug_pages_view); -out: - if (!rc) + if (rc) { + mutex_lock(&debug_mutex); + _debug_register(rc); + mutex_unlock(&debug_mutex); + } else { pr_err("Registering debug feature %s failed\n", name); - mutex_unlock(&debug_mutex); + } return rc; } EXPORT_SYMBOL(debug_register_mode); @@ -718,6 +705,27 @@ debug_info_t *debug_register(const char *name, int pages_per_area, } EXPORT_SYMBOL(debug_register);
+/* Remove debugfs entries and remove from internal list. */ +static void _debug_unregister(debug_info_t *id) +{ + int i; + + for (i = 0; i < DEBUG_MAX_VIEWS; i++) { + if (!id->views[i]) + continue; + debugfs_remove(id->debugfs_entries[i]); + } + debugfs_remove(id->debugfs_root_entry); + if (id == debug_area_first) + debug_area_first = id->next; + if (id == debug_area_last) + debug_area_last = id->prev; + if (id->prev) + id->prev->next = id->next; + if (id->next) + id->next->prev = id->prev; +} + /** * debug_unregister() - give back debug area. * @@ -731,8 +739,10 @@ void debug_unregister(debug_info_t *id) if (!id) return; mutex_lock(&debug_mutex); - debug_info_put(id); + _debug_unregister(id); mutex_unlock(&debug_mutex); + + debug_info_put(id); } EXPORT_SYMBOL(debug_unregister);