6.8-stable review patch. If anyone has any objections, please let me know.
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From: Beau Belgrave beaub@linux.microsoft.com
[ Upstream commit 1e953de9e9b4ca77a9ce0fc17a0778eba3a4ca64 ]
The current code for finding and deleting events assumes that there will never be cases when user_events are registered with the same name, but different formats. Scenarios exist where programs want to use the same name but have different formats. An example is multiple versions of a program running side-by-side using the same event name, but with updated formats in each version.
This change does not yet allow for multi-format events. If user_events are registered with the same name but different arguments the programs see the same return values as before. This change simply makes it possible to easily accommodate for this.
Update find_user_event() to take in argument parameters and register flags to accommodate future multi-format event scenarios. Have find validate argument matching and return error pointers to cover when an existing event has the same name but different format. Update callers to handle error pointer logic.
Move delete_user_event() to use hash walking directly now that find_user_event() has changed. Delete all events found that match the register name, stop if an error occurs and report back to the user.
Update user_fields_match() to cover list_empty() scenarios now that find_user_event() uses it directly. This makes the logic consistent across several callsites.
Link: https://lore.kernel.org/linux-trace-kernel/20240222001807.1463-2-beaub@linux...
Signed-off-by: Beau Belgrave beaub@linux.microsoft.com Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org Stable-dep-of: bd125a084091 ("tracing/user_events: Fix non-spaced field matching") Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/trace/trace_events_user.c | 107 +++++++++++++++++-------------- 1 file changed, 59 insertions(+), 48 deletions(-)
diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c index e76f5e1efdf2d..fce5ed5fec50f 100644 --- a/kernel/trace/trace_events_user.c +++ b/kernel/trace/trace_events_user.c @@ -202,6 +202,8 @@ static struct user_event_mm *user_event_mm_get(struct user_event_mm *mm); static struct user_event_mm *user_event_mm_get_all(struct user_event *user); static void user_event_mm_put(struct user_event_mm *mm); static int destroy_user_event(struct user_event *user); +static bool user_fields_match(struct user_event *user, int argc, + const char **argv);
static u32 user_event_key(char *name) { @@ -1493,17 +1495,24 @@ static int destroy_user_event(struct user_event *user) }
static struct user_event *find_user_event(struct user_event_group *group, - char *name, u32 *outkey) + char *name, int argc, const char **argv, + u32 flags, u32 *outkey) { struct user_event *user; u32 key = user_event_key(name);
*outkey = key;
- hash_for_each_possible(group->register_table, user, node, key) - if (!strcmp(EVENT_NAME(user), name)) + hash_for_each_possible(group->register_table, user, node, key) { + if (strcmp(EVENT_NAME(user), name)) + continue; + + if (user_fields_match(user, argc, argv)) return user_event_get(user);
+ return ERR_PTR(-EADDRINUSE); + } + return NULL; }
@@ -1860,6 +1869,9 @@ static bool user_fields_match(struct user_event *user, int argc, struct list_head *head = &user->fields; int i = 0;
+ if (argc == 0) + return list_empty(head); + list_for_each_entry_reverse(field, head, link) { if (!user_field_match(field, argc, argv, &i)) return false; @@ -1880,10 +1892,8 @@ static bool user_event_match(const char *system, const char *event, match = strcmp(EVENT_NAME(user), event) == 0 && (!system || strcmp(system, USER_EVENTS_SYSTEM) == 0);
- if (match && argc > 0) + if (match) match = user_fields_match(user, argc, argv); - else if (match && argc == 0) - match = list_empty(&user->fields);
return match; } @@ -1922,11 +1932,11 @@ static int user_event_parse(struct user_event_group *group, char *name, char *args, char *flags, struct user_event **newuser, int reg_flags) { - int ret; - u32 key; struct user_event *user; + char **argv = NULL; int argc = 0; - char **argv; + int ret; + u32 key;
/* Currently don't support any text based flags */ if (flags != NULL) @@ -1935,41 +1945,34 @@ static int user_event_parse(struct user_event_group *group, char *name, if (!user_event_capable(reg_flags)) return -EPERM;
+ if (args) { + argv = argv_split(GFP_KERNEL, args, &argc); + + if (!argv) + return -ENOMEM; + } + /* Prevent dyn_event from racing */ mutex_lock(&event_mutex); - user = find_user_event(group, name, &key); + user = find_user_event(group, name, argc, (const char **)argv, + reg_flags, &key); mutex_unlock(&event_mutex);
- if (user) { - if (args) { - argv = argv_split(GFP_KERNEL, args, &argc); - if (!argv) { - ret = -ENOMEM; - goto error; - } + if (argv) + argv_free(argv);
- ret = user_fields_match(user, argc, (const char **)argv); - argv_free(argv); - - } else - ret = list_empty(&user->fields); - - if (ret) { - *newuser = user; - /* - * Name is allocated by caller, free it since it already exists. - * Caller only worries about failure cases for freeing. - */ - kfree(name); - } else { - ret = -EADDRINUSE; - goto error; - } + if (IS_ERR(user)) + return PTR_ERR(user); + + if (user) { + *newuser = user; + /* + * Name is allocated by caller, free it since it already exists. + * Caller only worries about failure cases for freeing. + */ + kfree(name);
return 0; -error: - user_event_put(user, false); - return ret; }
user = kzalloc(sizeof(*user), GFP_KERNEL_ACCOUNT); @@ -2052,25 +2055,33 @@ static int user_event_parse(struct user_event_group *group, char *name, }
/* - * Deletes a previously created event if it is no longer being used. + * Deletes previously created events if they are no longer being used. */ static int delete_user_event(struct user_event_group *group, char *name) { - u32 key; - struct user_event *user = find_user_event(group, name, &key); + struct user_event *user; + struct hlist_node *tmp; + u32 key = user_event_key(name); + int ret = -ENOENT;
- if (!user) - return -ENOENT; + /* Attempt to delete all event(s) with the name passed in */ + hash_for_each_possible_safe(group->register_table, user, tmp, node, key) { + if (strcmp(EVENT_NAME(user), name)) + continue;
- user_event_put(user, true); + if (!user_event_last_ref(user)) + return -EBUSY;
- if (!user_event_last_ref(user)) - return -EBUSY; + if (!user_event_capable(user->reg_flags)) + return -EPERM;
- if (!user_event_capable(user->reg_flags)) - return -EPERM; + ret = destroy_user_event(user);
- return destroy_user_event(user); + if (ret) + goto out; + } +out: + return ret; }
/*