module: Fix up module_notifier return values

While auditing all module notifiers I noticed a whole bunch of fail
wrt the return value. Notifiers have a 'special' return semantics.

As is; NOTIFY_DONE vs NOTIFY_OK is a bit vague; but
notifier_from_errno(0) results in NOTIFY_OK and NOTIFY_DONE has a
comment that says "Don't care".

From this I've used NOTIFY_DONE when the function completely ignores
the callback and notifier_to_error() isn't used.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Reviewed-by: Robert Richter <rric@kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20200818135804.385360407@infradead.org

diff --git a/drivers/oprofile/buffer_sync.c b/drivers/oprofile/buffer_sync.c
index 4d76952..cc91786 100644 (file)
--- a/drivers/oprofile/buffer_sync.c
+++ b/drivers/oprofile/buffer_sync.c
@@ -116,7 +116,7 @@ module_load_notify(struct notifier_block *self, unsigned long val, void *data)
 {
 #ifdef CONFIG_MODULES
        if (val != MODULE_STATE_COMING)
-               return 0;
+               return NOTIFY_DONE;
 
        /* FIXME: should we process all CPU buffers ? */
        mutex_lock(&buffer_mutex);
@@ -124,7 +124,7 @@ module_load_notify(struct notifier_block *self, unsigned long val, void *data)
        add_event_entry(MODULE_LOADED_CODE);
        mutex_unlock(&buffer_mutex);
 #endif
-       return 0;
+       return NOTIFY_OK;
 }
 
 

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index a8d4f25..2ecf789 100644 (file)
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2027,10 +2027,11 @@ static int bpf_event_notify(struct notifier_block *nb, unsigned long op,
 {
        struct bpf_trace_module *btm, *tmp;
        struct module *mod = module;
+       int ret = 0;
 
        if (mod->num_bpf_raw_events == 0 ||
            (op != MODULE_STATE_COMING && op != MODULE_STATE_GOING))
-               return 0;
+               goto out;
 
        mutex_lock(&bpf_module_mutex);
 
@@ -2040,6 +2041,8 @@ static int bpf_event_notify(struct notifier_block *nb, unsigned long op,
                if (btm) {
                        btm->module = module;
                        list_add(&btm->list, &bpf_trace_modules);
+               } else {
+                       ret = -ENOMEM;
                }
                break;
        case MODULE_STATE_GOING:
@@ -2055,7 +2058,8 @@ static int bpf_event_notify(struct notifier_block *nb, unsigned long op,
 
        mutex_unlock(&bpf_module_mutex);
 
-       return 0;
+out:
+       return notifier_from_errno(ret);
 }
 
 static struct notifier_block bpf_module_nb = {

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index f40d850..df49992 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -9072,7 +9072,7 @@ static int trace_module_notify(struct notifier_block *self,
                break;
        }
 
-       return 0;
+       return NOTIFY_OK;
 }
 
 static struct notifier_block trace_module_nb = {

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index a85effb..beebf2c 100644 (file)
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -2646,7 +2646,7 @@ static int trace_module_notify(struct notifier_block *self,
        mutex_unlock(&trace_types_lock);
        mutex_unlock(&event_mutex);
 
-       return 0;
+       return NOTIFY_OK;
 }
 
 static struct notifier_block trace_module_nb = {

diff --git a/kernel/trace/trace_printk.c b/kernel/trace/trace_printk.c
index d4e31e9..bb7783b 100644 (file)
--- a/kernel/trace/trace_printk.c
+++ b/kernel/trace/trace_printk.c
@@ -96,7 +96,7 @@ static int module_trace_bprintk_format_notify(struct notifier_block *self,
                if (val == MODULE_STATE_COMING)
                        hold_module_trace_bprintk_format(start, end);
        }
-       return 0;
+       return NOTIFY_OK;
 }
 
 /*
@@ -174,7 +174,7 @@ __init static int
 module_trace_bprintk_format_notify(struct notifier_block *self,
                unsigned long val, void *data)
 {
-       return 0;
+       return NOTIFY_OK;
 }
 static inline const char **
 find_next_mod_format(int start_index, void *v, const char **fmt, loff_t *pos)

diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 73956ea..8e05ed2 100644 (file)
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -521,7 +521,7 @@ static int tracepoint_module_notify(struct notifier_block *self,
        case MODULE_STATE_UNFORMED:
                break;
        }
-       return ret;
+       return notifier_from_errno(ret);
 }
 
 static struct notifier_block tracepoint_module_nb = {