Commit 048714d9 authored by David Carlier's avatar David Carlier Committed by Tejun Heo
Browse files

tools/sched_ext: scx_userland: fix restart and stats thread lifecycle bugs 



Fix three issues in scx_userland's restart path:

- exit_req is not reset on restart, causing sched_main_loop() to exit
  immediately without doing any scheduling work.

- stats_printer thread handle is local to spawn_stats_thread(), making
  it impossible to join from main(). Promote it to file scope.

- The stats thread continues reading skel->bss after the skeleton is
  destroyed on restart, causing a use-after-free. Join the stats thread
  before destroying the skeleton to ensure it has exited.

Signed-off-by: default avatarDavid Carlier <devnexen@gmail.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 988369d2

tools/sched_ext/scx_userland.c

+3 −2
Original line number Diff line number Diff line
@@ -54,6 +54,7 @@ static bool verbose; 
static volatile int exit_req;

static int enqueued_fd, dispatched_fd;



static pthread_t stats_printer;

static struct scx_userland *skel;

static struct bpf_link *ops_link;
@@ -319,8 +320,6 @@ static void *run_stats_printer(void *arg) 


static int spawn_stats_thread(void)

{

	pthread_t stats_printer;



	return pthread_create(&stats_printer, NULL, run_stats_printer, NULL);

}
@@ -375,6 +374,7 @@ static void pre_bootstrap(int argc, char **argv) 


static void bootstrap(char *comm)

{

	exit_req = 0;

	skel = SCX_OPS_OPEN(userland_ops, scx_userland);



	skel->rodata->num_possible_cpus = libbpf_num_possible_cpus();
@@ -428,6 +428,7 @@ int main(int argc, char **argv) 


	exit_req = 1;

	bpf_link__destroy(ops_link);

	pthread_join(stats_printer, NULL);

	ecode = UEI_REPORT(skel, uei);

	scx_userland__destroy(skel);