From 29930c6bde25e0a6ed2c9b6400545e1937e38379 Mon Sep 17 00:00:00 2001 From: Luis Henriques Date: Tue, 9 Sep 2014 22:49:41 +0100 Subject: tracing: Fix tracing_stat return values in error handling paths [ Upstream commit afccc00f75bbbee4e4ae833a96c2d29a7259c693 ] tracing_stat_init() was always returning '0', even on the error paths. It now returns -ENODEV if tracing_init_dentry() fails or -ENOMEM if it fails to created the 'trace_stat' debugfs directory. Link: http://lkml.kernel.org/r/1410299381-20108-1-git-send-email-luis.henriques@canonical.com Fixes: ed6f1c996bfe4 ("tracing: Check return value of tracing_init_dentry()") Signed-off-by: Luis Henriques [ Pulled from the archeological digging of my INBOX ] Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Sasha Levin --- kernel/trace/trace_stat.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'kernel/trace/trace_stat.c') diff --git a/kernel/trace/trace_stat.c b/kernel/trace/trace_stat.c index 413ff108fbd0..bc97b10e56cc 100644 --- a/kernel/trace/trace_stat.c +++ b/kernel/trace/trace_stat.c @@ -277,18 +277,22 @@ static int tracing_stat_init(void) d_tracing = tracing_init_dentry(); if (IS_ERR(d_tracing)) - return 0; + return -ENODEV; stat_dir = tracefs_create_dir("trace_stat", d_tracing); - if (!stat_dir) + if (!stat_dir) { pr_warn("Could not create tracefs 'trace_stat' entry\n"); + return -ENOMEM; + } return 0; } static int init_stat_file(struct stat_session *session) { - if (!stat_dir && tracing_stat_init()) - return -ENODEV; + int ret; + + if (!stat_dir && (ret = tracing_stat_init())) + return ret; session->file = tracefs_create_file(session->ts->name, 0644, stat_dir, -- cgit v1.2.3 From 373e93e92d7ccd2a5c584c3c624ff2252c3fae25 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Fri, 24 Jan 2020 17:47:49 -0500 Subject: tracing: Fix very unlikely race of registering two stat tracers [ Upstream commit dfb6cd1e654315168e36d947471bd2a0ccd834ae ] Looking through old emails in my INBOX, I came across a patch from Luis Henriques that attempted to fix a race of two stat tracers registering the same stat trace (extremely unlikely, as this is done in the kernel, and probably doesn't even exist). The submitted patch wasn't quite right as it needed to deal with clean up a bit better (if two stat tracers were the same, it would have the same files). But to make the code cleaner, all we needed to do is to keep the all_stat_sessions_mutex held for most of the registering function. Link: http://lkml.kernel.org/r/1410299375-20068-1-git-send-email-luis.henriques@canonical.com Fixes: 002bb86d8d42f ("tracing/ftrace: separate events tracing and stats tracing engine") Reported-by: Luis Henriques Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Sasha Levin --- kernel/trace/trace_stat.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) (limited to 'kernel/trace/trace_stat.c') diff --git a/kernel/trace/trace_stat.c b/kernel/trace/trace_stat.c index bc97b10e56cc..d19f2191960e 100644 --- a/kernel/trace/trace_stat.c +++ b/kernel/trace/trace_stat.c @@ -305,7 +305,7 @@ static int init_stat_file(struct stat_session *session) int register_stat_tracer(struct tracer_stat *trace) { struct stat_session *session, *node; - int ret; + int ret = -EINVAL; if (!trace) return -EINVAL; @@ -316,17 +316,15 @@ int register_stat_tracer(struct tracer_stat *trace) /* Already registered? */ mutex_lock(&all_stat_sessions_mutex); list_for_each_entry(node, &all_stat_sessions, session_list) { - if (node->ts == trace) { - mutex_unlock(&all_stat_sessions_mutex); - return -EINVAL; - } + if (node->ts == trace) + goto out; } - mutex_unlock(&all_stat_sessions_mutex); + ret = -ENOMEM; /* Init the session */ session = kzalloc(sizeof(*session), GFP_KERNEL); if (!session) - return -ENOMEM; + goto out; session->ts = trace; INIT_LIST_HEAD(&session->session_list); @@ -335,15 +333,16 @@ int register_stat_tracer(struct tracer_stat *trace) ret = init_stat_file(session); if (ret) { destroy_session(session); - return ret; + goto out; } + ret = 0; /* Register */ - mutex_lock(&all_stat_sessions_mutex); list_add_tail(&session->session_list, &all_stat_sessions); + out: mutex_unlock(&all_stat_sessions_mutex); - return 0; + return ret; } void unregister_stat_tracer(struct tracer_stat *trace) -- cgit v1.2.3