OpenE2K
/
linux
6
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Commit 79c6f448c8 ("tracing: Fix hwlat kthread migration") fixed a 

bug that was caused by a race condition in initializing the hwlat
 thread. When fixing this code, I realized that it should have been done
 differently. Instead of doing the rewrite and sending that to stable,
 I just sent the above commit to fix the bug that should be back ported.
 
 This commit is on top of the quick fix commit to rewrite the code the
 way it should have been written in the first place.
 -----BEGIN PGP SIGNATURE-----
 
 iQExBAABCAAbBQJYtDsNFBxyb3N0ZWR0QGdvb2RtaXMub3JnAAoJEMm5BfJq2Y3L
 +CQH/0BhSwjiCnlHAkHNFKn47O0yDtxBLj8ar4bUQRacDXeQyAGDP13hn3q3LvG9
 CRzDXaYrusA3fjGcgmtyU33am6LK84dPn5u2HSyEalDZNBel8l6oYLUZVWLgef02
 x43949nOeBy+KO02Y118zGyxFEPtYBnCVpguMa4vdVgnr04gECo2VH5FjnLMslKM
 W1j/WrbVaO8WObh7X01JZzozWwp3McW4x6H8PUWaHjnhN/Iv6+YGtNN/Sa4cq4V/
 CyCfxrZvN/Y/uMSGzVlhuXxeRc2PRsjjmAqN+8P4KZIGW5BstdiWbrVj+KaBLR9z
 6QERD3atiEIYI/QGEep7ZH795PI=
 =Bdwk
 -----END PGP SIGNATURE-----

Merge tag 'trace-v4.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull another tracing update from Steven Rostedt:
 "Commit 79c6f448c8 ("tracing: Fix hwlat kthread migration") fixed a
  bug that was caused by a race condition in initializing the hwlat
  thread. When fixing this code, I realized that it should have been
  done differently. Instead of doing the rewrite and sending that to
  stable, I just sent the above commit to fix the bug that should be
  back ported.

  This commit is on top of the quick fix commit to rewrite the code the
  way it should have been written in the first place"

* tag 'trace-v4.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Clean up the hwlat binding code
This commit is contained in:
Linus Torvalds 2017-02-27 13:36:19 -08:00
parent 79b17ea740 f447c196fe
commit 45554b2357
1 changed files with 17 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
kernel/trace/trace_hwlat.c
View File

@ -266,24 +266,13 @@ out:
static struct cpumask save_cpumask;
static bool disable_migrate;
static void move_to_next_cpu(bool initmask)
static void move_to_next_cpu(void)
{
static struct cpumask *current_mask;
struct cpumask *current_mask = &save_cpumask;
int next_cpu;
if (disable_migrate)
return;
/* Just pick the first CPU on first iteration */
if (initmask) {
current_mask = &save_cpumask;
get_online_cpus();
cpumask_and(current_mask, cpu_online_mask, tracing_buffer_mask);
put_online_cpus();
next_cpu = cpumask_first(current_mask);
goto set_affinity;
}
/*
* If for some reason the user modifies the CPU affinity
* of this thread, than stop migrating for the duration
@ -300,7 +289,6 @@ static void move_to_next_cpu(bool initmask)
if (next_cpu >= nr_cpu_ids)
next_cpu = cpumask_first(current_mask);
set_affinity:
if (next_cpu >= nr_cpu_ids) /* Shouldn't happen! */
goto disable;
@ -327,12 +315,10 @@ static void move_to_next_cpu(bool initmask)
static int kthread_fn(void *data)
{
u64 interval;
bool initmask = true;
while (!kthread_should_stop()) {
move_to_next_cpu(initmask);
initmask = false;
move_to_next_cpu();
local_irq_disable();
get_sample();
@ -363,13 +349,27 @@ static int kthread_fn(void *data)
*/
static int start_kthread(struct trace_array *tr)
{
struct cpumask *current_mask = &save_cpumask;
struct task_struct *kthread;
int next_cpu;
/* Just pick the first CPU on first iteration */
current_mask = &save_cpumask;
get_online_cpus();
cpumask_and(current_mask, cpu_online_mask, tracing_buffer_mask);
put_online_cpus();
next_cpu = cpumask_first(current_mask);
kthread = kthread_create(kthread_fn, NULL, "hwlatd");
if (IS_ERR(kthread)) {
pr_err(BANNER "could not start sampling thread\n");
return -ENOMEM;
}
cpumask_clear(current_mask);
cpumask_set_cpu(next_cpu, current_mask);
sched_setaffinity(kthread->pid, current_mask);
hwlat_kthread = kthread;
wake_up_process(kthread);