@@ -2254,7 +2254,7 @@ static void ftrace_startup_sysctl(void)
command = FTRACE_UPDATE_CALLS;
if (ftrace_graph_active)
command |= FTRACE_START_FUNC_RET;
- ftrace_run_update_code(command);
+ ftrace_startup_enable(command);
}
}
@@ -4900,12 +4900,12 @@ ftrace_enable_sysctl(struct ctl_table *table, int write,
if (ftrace_enabled) {
- ftrace_startup_sysctl();
-
/* we are starting ftrace again */
if (ftrace_ops_list != &ftrace_list_end)
update_ftrace_function();
+ ftrace_startup_sysctl();
+
} else {
/* stopping ftrace calls (just send to ftrace_stub) */
ftrace_trace_function = ftrace_stub;
This is a note to let you know that I have just added a patch titled ftrace: Fix ftrace enable ordering of sysctl ftrace_enabled to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue This patch is scheduled to be released in version 3.13.11-ckt19. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.13.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From f9e64f22e10bffbec34fd2763bc38c047d88b20a Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org> Date: Fri, 6 Mar 2015 19:55:13 -0500 Subject: ftrace: Fix ftrace enable ordering of sysctl ftrace_enabled commit 524a38682573b2e15ab6317ccfe50280441514be upstream. Some archs (specifically PowerPC), are sensitive with the ordering of the enabling of the calls to function tracing and setting of the function to use to be traced. That is, update_ftrace_function() sets what function the ftrace_caller trampoline should call. Some archs require this to be set before calling ftrace_run_update_code(). Another bug was discovered, that ftrace_startup_sysctl() called ftrace_run_update_code() directly. If the function the ftrace_caller trampoline changes, then it will not be updated. Instead a call to ftrace_startup_enable() should be called because it tests to see if the callback changed since the code was disabled, and will tell the arch to update appropriately. Most archs do not need this notification, but PowerPC does. The problem could be seen by the following commands: # echo 0 > /proc/sys/kernel/ftrace_enabled # echo function > /sys/kernel/debug/tracing/current_tracer # echo 1 > /proc/sys/kernel/ftrace_enabled # cat /sys/kernel/debug/tracing/trace The trace will show that function tracing was not active. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- kernel/trace/ftrace.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) -- 1.9.1