[PATCH 2/3] module: Fix up module_notifier return values.

From: Peter Zijlstra
Date: Mon Jun 24 2019 - 05:24:57 EST


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

Cc: Robert Richter <rric@xxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: Martin KaFai Lau <kafai@xxxxxx>
Cc: Song Liu <songliubraving@xxxxxx>
Cc: Yonghong Song <yhs@xxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxx>
Cc: "Joel Fernandes (Google)" <joel@xxxxxxxxxxxxxxxxx>
Cc: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: oprofile-list@xxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: netdev@xxxxxxxxxxxxxxx
Cc: bpf@xxxxxxxxxxxxxxx
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
drivers/oprofile/buffer_sync.c | 4 ++--
kernel/module.c | 9 +++++----
kernel/trace/bpf_trace.c | 8 ++++++--
kernel/trace/trace.c | 2 +-
kernel/trace/trace_events.c | 2 +-
kernel/trace/trace_printk.c | 4 ++--
kernel/tracepoint.c | 2 +-
7 files changed, 18 insertions(+), 13 deletions(-)

--- a/drivers/oprofile/buffer_sync.c
+++ b/drivers/oprofile/buffer_sync.c
@@ -116,7 +116,7 @@ module_load_notify(struct notifier_block
{
#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
add_event_entry(MODULE_LOADED_CODE);
mutex_unlock(&buffer_mutex);
#endif
- return 0;
+ return NOTIFY_OK;
}


--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1302,10 +1302,11 @@ static int bpf_event_notify(struct notif
{
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);

@@ -1315,6 +1316,8 @@ static int bpf_event_notify(struct notif
if (btm) {
btm->module = module;
list_add(&btm->list, &bpf_trace_modules);
+ } else {
+ ret = -ENOMEM;
}
break;
case MODULE_STATE_GOING:
@@ -1330,7 +1333,8 @@ static int bpf_event_notify(struct notif

mutex_unlock(&bpf_module_mutex);

- return 0;
+out:
+ return notifier_from_errno(ret);
}

static struct notifier_block bpf_module_nb = {
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -8685,7 +8685,7 @@ static int trace_module_notify(struct no
break;
}

- return 0;
+ return NOTIFY_OK;
}

static struct notifier_block trace_module_nb = {
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -2450,7 +2450,7 @@ static int trace_module_notify(struct no
mutex_unlock(&trace_types_lock);
mutex_unlock(&event_mutex);

- return 0;
+ return NOTIFY_OK;
}

static struct notifier_block trace_module_nb = {
--- a/kernel/trace/trace_printk.c
+++ b/kernel/trace/trace_printk.c
@@ -95,7 +95,7 @@ static int module_trace_bprintk_format_n
if (val == MODULE_STATE_COMING)
hold_module_trace_bprintk_format(start, end);
}
- return 0;
+ return NOTIFY_OK;
}

/*
@@ -173,7 +173,7 @@ __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)
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -538,7 +538,7 @@ static int tracepoint_module_notify(stru
case MODULE_STATE_UNFORMED:
break;
}
- return ret;
+ return notifier_from_errno(ret);
}

static struct notifier_block tracepoint_module_nb = {