Commit 7639dad9 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'trace-v4.7-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace 

Pull motr tracing updates from Steven Rostedt:
 "Three more changes.

   - I forgot that I had another selftest to stress test the ftrace
     instance creation.  It was actually suppose to go into the 4.6
     merge window, but I never committed it.  I almost forgot about it
     again, but noticed it was missing from your tree.

   - Soumya PN sent me a clean up patch to not disable interrupts when
     taking the tasklist_lock for read, as it's unnecessary because that
     lock is never taken for write in irq context.

   - Newer gcc's can cause the jump in the function_graph code to the
     global ftrace_stub label to be a short jump instead of a long one.
     As that jump is dynamically converted to jump to the trace code to
     do function graph tracing, and that conversion expects a long jump
     it can corrupt the ftrace_stub itself (it's directly after that
     call).  One way to prevent gcc from using a short jump is to
     declare the ftrace_stub as a weak function, which we do here to
     keep gcc from optimizing too much"

* tag 'trace-v4.7-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ftrace/x86: Set ftrace_stub to weak to prevent gcc from using short jumps to it
  ftrace: Don't disable irqs when taking the tasklist_lock read_lock
  ftracetest: Add instance created, delete, read and enable event test
parents 77ed402b 8329e818

arch/x86/kernel/mcount_64.S

+2 −1
Original line number Diff line number Diff line
@@ -182,7 +182,8 @@ GLOBAL(ftrace_graph_call) 
	jmp ftrace_stub

#endif



GLOBAL(ftrace_stub)

/* This is weak to keep gas from relaxing the jumps */

WEAK(ftrace_stub)

	retq

END(ftrace_caller)

kernel/trace/ftrace.c

+2 −3
Original line number Diff line number Diff line
@@ -5737,7 +5737,6 @@ static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list) 
{

	int i;

	int ret = 0;

	unsigned long flags;

	int start = 0, end = FTRACE_RETSTACK_ALLOC_SIZE;

	struct task_struct *g, *t;
@@ -5753,7 +5752,7 @@ static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list) 
		}

	}



	read_lock_irqsave(&tasklist_lock, flags);

	read_lock(&tasklist_lock);

	do_each_thread(g, t) {

		if (start == end) {

			ret = -EAGAIN;
@@ -5771,7 +5770,7 @@ static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list) 
	} while_each_thread(g, t);



unlock:

	read_unlock_irqrestore(&tasklist_lock, flags);

	read_unlock(&tasklist_lock);

free:

	for (i = start; i < end; i++)

		kfree(ret_stack_list[i]);

tools/testing/selftests/ftrace/test.d/instances/instance-event.tc

0 → 100644
+143 −0
Original line number Diff line number Diff line 
#!/bin/sh

# description: Test creation and deletion of trace instances while setting an event



if [ ! -d instances ] ; then

    echo "no instance directory with this kernel"

    exit_unsupported;

fi



fail() { # mesg

    rmdir foo 2>/dev/null

    echo $1

    set -e

    exit $FAIL

}



cd instances



# we don't want to fail on error

set +e



mkdir x

rmdir x

result=$?



if [ $result -ne 0 ]; then

    echo "instance rmdir not supported"

    exit_unsupported

fi



instance_slam() {

        while :; do

                mkdir foo 2> /dev/null

                rmdir foo 2> /dev/null

        done

}



instance_read() {

        while :; do

                cat foo/trace 1> /dev/null 2>&1

        done

}



instance_set() {

        while :; do

                echo 1 > foo/events/sched/sched_switch

        done 2> /dev/null

}



instance_slam &

p1=$!

echo $p1



instance_set &

p2=$!

echo $p2



instance_read &

p3=$!

echo $p3



sleep 1



kill -1 $p3

kill -1 $p2

kill -1 $p1



echo "Wait for processes to finish"

wait $p1 $p2 $p3

echo "all processes finished, wait for cleanup"

sleep 1



mkdir foo

ls foo > /dev/null

rmdir foo

if [ -d foo ]; then

        fail "foo still exists"

fi

exit 0









instance_slam() {

    while :; do

	mkdir x

	mkdir y

	mkdir z

	rmdir x

	rmdir y

	rmdir z

    done 2>/dev/null

}



instance_slam &

x=`jobs -l`

p1=`echo $x | cut -d' ' -f2`

echo $p1



instance_slam &

x=`jobs -l | tail -1`

p2=`echo $x | cut -d' ' -f2`

echo $p2



instance_slam &

x=`jobs -l | tail -1`

p3=`echo $x | cut -d' ' -f2`

echo $p3



instance_slam &

x=`jobs -l | tail -1`

p4=`echo $x | cut -d' ' -f2`

echo $p4



instance_slam &

x=`jobs -l | tail -1`

p5=`echo $x | cut -d' ' -f2`

echo $p5



ls -lR >/dev/null

sleep 1



kill -1 $p1

kill -1 $p2

kill -1 $p3

kill -1 $p4

kill -1 $p5



echo "Wait for processes to finish"

wait $p1 $p2 $p3 $p4 $p5

echo "all processes finished, wait for cleanup"



mkdir x y z

ls x y z

rmdir x y z

for d in x y z; do

        if [ -d $d ]; then

                fail "instance $d still exists"

        fi

done



set -e



exit 0

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