Messages in this thread Patch in this message | | | From | Beau Belgrave <> | Subject | [PATCH] tracing/user_events: Remove user_ns walk for groups | Date | Thu, 1 Jun 2023 15:49:28 -0700 |
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During discussions it was suggested that user_ns is not a good place to try to attach a tracing namespace. The current code has stubs to enable that work that are very likely to change and incur a performance cost.
Remove the user_ns walk when creating a group and determining the system name to use, since it's unlikely user_ns will be used in the future.
Link: https://lore.kernel.org/all/20230601-urenkel-holzofen-cd9403b9cadd@brauner/
Suggested-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com> --- kernel/trace/trace_events_user.c | 42 ++++---------------------------- 1 file changed, 5 insertions(+), 37 deletions(-)
diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c index b1ecd7677642..55e362484b66 100644 --- a/kernel/trace/trace_events_user.c +++ b/kernel/trace/trace_events_user.c @@ -180,21 +180,11 @@ static void user_event_group_destroy(struct user_event_group *group) kfree(group); } -static char *user_event_group_system_name(struct user_namespace *user_ns) +static char *user_event_group_system_name(void) { char *system_name; int len = sizeof(USER_EVENTS_SYSTEM) + 1; - if (user_ns != &init_user_ns) { - /* - * Unexpected at this point: - * We only currently support init_user_ns. - * When we enable more, this will trigger a failure so log. - */ - pr_warn("user_events: Namespace other than init_user_ns!\n"); - return NULL; - } - system_name = kmalloc(len, GFP_KERNEL); if (!system_name) @@ -205,34 +195,12 @@ static char *user_event_group_system_name(struct user_namespace *user_ns) return system_name; } -static inline struct user_event_group -*user_event_group_from_user_ns(struct user_namespace *user_ns) -{ - if (user_ns == &init_user_ns) - return init_group; - - return NULL; -} - static struct user_event_group *current_user_event_group(void) { - struct user_namespace *user_ns = current_user_ns(); - struct user_event_group *group = NULL; - - while (user_ns) { - group = user_event_group_from_user_ns(user_ns); - - if (group) - break; - - user_ns = user_ns->parent; - } - - return group; + return init_group; } -static struct user_event_group -*user_event_group_create(struct user_namespace *user_ns) +static struct user_event_group *user_event_group_create(void) { struct user_event_group *group; @@ -241,7 +209,7 @@ static struct user_event_group if (!group) return NULL; - group->system_name = user_event_group_system_name(user_ns); + group->system_name = user_event_group_system_name(); if (!group->system_name) goto error; @@ -2543,7 +2511,7 @@ static int __init trace_events_user_init(void) if (!fault_cache) return -ENOMEM; - init_group = user_event_group_create(&init_user_ns); + init_group = user_event_group_create(); if (!init_group) { kmem_cache_destroy(fault_cache); base-commit: 3862f86c1529fa0016de6344eb974877b4cd3838 -- 2.25.1
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