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author | Linus Torvalds <torvalds@linux-foundation.org> | 2016-05-23 04:40:39 +0200 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-05-23 04:40:39 +0200 |
commit | 7639dad93a5564579987abded4ec05e3db13659d (patch) | |
tree | d786a45e79672ee3ea04e93d60ec1da02cb17940 | |
parent | Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg... (diff) | |
parent | ftrace/x86: Set ftrace_stub to weak to prevent gcc from using short jumps to it (diff) | |
download | linux-7639dad93a5564579987abded4ec05e3db13659d.tar.xz linux-7639dad93a5564579987abded4ec05e3db13659d.zip |
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
-rw-r--r-- | arch/x86/kernel/mcount_64.S | 3 | ||||
-rw-r--r-- | kernel/trace/ftrace.c | 5 | ||||
-rw-r--r-- | tools/testing/selftests/ftrace/test.d/instances/instance-event.tc | 143 |
3 files changed, 147 insertions, 4 deletions
diff --git a/arch/x86/kernel/mcount_64.S b/arch/x86/kernel/mcount_64.S index ed48a9f465f8..61924222a9e1 100644 --- a/arch/x86/kernel/mcount_64.S +++ b/arch/x86/kernel/mcount_64.S @@ -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) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index a6c8252d7776..900dbb1efff2 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -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]); diff --git a/tools/testing/selftests/ftrace/test.d/instances/instance-event.tc b/tools/testing/selftests/ftrace/test.d/instances/instance-event.tc new file mode 100644 index 000000000000..5f2abd03f16b --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/instances/instance-event.tc @@ -0,0 +1,143 @@ +#!/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 |