tracing: Add tracing_reset_all_online_cpus_unlocked() function

commit e18eb8783ec4949adebc7d7b0fdb65f65bfeefd9 upstream.

Currently the tracing_reset_all_online_cpus() requires the
trace_types_lock held. But only one caller of this function actually has
that lock held before calling it, and the other just takes the lock so
that it can call it. More users of this function is needed where the lock
is not held.

Add a tracing_reset_all_online_cpus_unlocked() function for the one use
case that calls it without being held, and also add a lockdep_assert to
make sure it is held when called.

Then have tracing_reset_all_online_cpus() take the lock internally, such
that callers do not need to worry about taking it.

Link: https://lkml.kernel.org/r/20221123192741.658273220@goodmis.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d068124815bc3c649e0ef27b0bc48004f6d80ee7..219cd2c819369375083b21058e8a261b6800d8db 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1931,10 +1931,12 @@ void tracing_reset_online_cpus(struct trace_buffer *buf)
 }
 
 /* Must have trace_types_lock held */
-void tracing_reset_all_online_cpus(void)
+void tracing_reset_all_online_cpus_unlocked(void)
 {
        struct trace_array *tr;
 
+       lockdep_assert_held(&trace_types_lock);
+
        list_for_each_entry(tr, &ftrace_trace_arrays, list) {
                if (!tr->clear_trace)
                        continue;
@@ -1946,6 +1948,13 @@ void tracing_reset_all_online_cpus(void)
        }
 }
 
+void tracing_reset_all_online_cpus(void)
+{
+       mutex_lock(&trace_types_lock);
+       tracing_reset_all_online_cpus_unlocked();
+       mutex_unlock(&trace_types_lock);
+}
+
 /*
  * The tgid_map array maps from pid to tgid; i.e. the value stored at index i
  * is the tgid last observed corresponding to pid=i.

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index f2ff39353e037feedc0d515a0e65a88678718290..edc17a640ab34c472c8a8836b7e3be622d8b5209 100644 (file)
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -677,6 +677,7 @@ int tracing_is_enabled(void);
 void tracing_reset_online_cpus(struct trace_buffer *buf);
 void tracing_reset_current(int cpu);
 void tracing_reset_all_online_cpus(void);
+void tracing_reset_all_online_cpus_unlocked(void);
 int tracing_open_generic(struct inode *inode, struct file *filp);
 int tracing_open_generic_tr(struct inode *inode, struct file *filp);
 bool tracing_is_disabled(void);

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 8f2cbc9ebb6e32c4c14673a44fee1deaf24e6f6e..a0675ecc8142ec526f5cf15bb1983e5aa14ea276 100644 (file)
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -2440,7 +2440,7 @@ static void trace_module_remove_events(struct module *mod)
         * over from this module may be passed to the new module events and
         * unexpected results may occur.
         */
-       tracing_reset_all_online_cpus();
+       tracing_reset_all_online_cpus_unlocked();
 }
 
 static int trace_module_notify(struct notifier_block *self,