tracing: Place trace_pid_list logic into abstract functions

Instead of having the logic that does trace_pid_list open coded, wrap it in
abstract functions. This will allow a rewrite of the logic that implements
the trace_pid_list without affecting the users.

Note, this causes a change in behavior. Every time a pid is written into
the set_*_pid file, it creates a new list and uses RCU to update it. If
pid_max is lowered, but there was a pid currently in the list that was
higher than pid_max, those pids will now be removed on updating the list.
The old behavior kept that from happening.

The rewrite of the pid_list logic will no longer depend on pid_max,
and will return the old behavior.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

1 files changed, 10 insertions, 4 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index b7c0f8e160fb..2ec500186992 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -22,6 +22,8 @@
 #include <linux/ctype.h>
 #include <linux/once_lite.h>
 
+#include "pid_list.h"
+
 #ifdef CONFIG_FTRACE_SYSCALLS
 #include <asm/unistd.h>		/* For NR_SYSCALLS	     */
 #include <asm/syscall.h>	/* some archs define it here */
@@ -188,10 +190,14 @@ struct trace_options {
 	struct trace_option_dentry	*topts;
 };
 
-struct trace_pid_list {
-	int				pid_max;
-	unsigned long			*pids;
-};
+struct trace_pid_list *trace_pid_list_alloc(void);
+void trace_pid_list_free(struct trace_pid_list *pid_list);
+bool trace_pid_list_is_set(struct trace_pid_list *pid_list, unsigned int pid);
+int trace_pid_list_set(struct trace_pid_list *pid_list, unsigned int pid);
+int trace_pid_list_clear(struct trace_pid_list *pid_list, unsigned int pid);
+int trace_pid_list_first(struct trace_pid_list *pid_list, unsigned int *pid);
+int trace_pid_list_next(struct trace_pid_list *pid_list, unsigned int pid,
+			unsigned int *next);
 
 enum {
 	TRACE_PIDS		= BIT(0),