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Commit 1e413cc6 authored by Philippe Gerum's avatar Philippe Gerum
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drivers/evl: hectic: allow userland to init wait mode 



The hectic utility needs to tell us whether some rtus/rtup/rtuo
threads are about to start waiting for an out-of-band event, so that
they don't miss a signal from the sleeper/switcher.

This information is now passed at UTASK registration time, which
ensures that HECTIC_OOB_WAIT is present in the task base flags early
enough before a SWITCH_TO request may target them.

Otherwise, the first evl_raise_flag() might be skipped in absence of
HECTIC_OOB_WAIT in the base flags of the target task, when the
sleeper/switcher manages to issue SWITCH_TO before such task enter the
PEND routine, which was seen at several occasions on very slow
platforms with 4+ CPUs (e.g. kvm-less qemu).

A typical test case involved running the following commands in
parallel on a 4-way configuration:

$ latmus
$ hectic rtuo2 rtuo3

In that case, tasks on CPU3 would miss the initial signal from the
sleeper/switcher.
Signed-off-by: Philippe Gerum's avatarPhilippe Gerum <rpm@xenomai.org>
parent 95f9b920
Hide whitespace changes
Inline Side-by-side
drivers/evl/hectic.c
View file @ 1e413cc6
......@@ -19,9 +19,7 @@
#include <asm/evl/fptest.h>
#include <uapi/evl/devices/hectic.h>
#define RTSWITCH_RT 0x10000
#define RTSWITCH_NRT 0
#define RTSWITCH_KERNEL 0x20000
#define HECTIC_KTHREAD 0x20000
struct rtswitch_context;
......@@ -69,22 +67,22 @@ static void handle_fpu_error(struct rtswitch_context *ctx,
ctx->failed = true;
ctx->error.fp_val = fp_out;
if ((cur->base.flags & RTSWITCH_RT) == RTSWITCH_RT)
if ((cur->base.flags & HECTIC_OOB_WAIT) == HECTIC_OOB_WAIT)
for (i = 0; i < ctx->tasks_count; i++) {
struct rtswitch_task *task = &ctx->tasks[i];
/* Find the first non kernel-space task. */
if ((task->base.flags & RTSWITCH_KERNEL))
if ((task->base.flags & HECTIC_KTHREAD))
continue;
/* Unblock it. */
switch(task->base.flags & RTSWITCH_RT) {
case RTSWITCH_NRT:
switch(task->base.flags & HECTIC_OOB_WAIT) {
case HECTIC_INBAND_WAIT:
ctx->utask = task;
irq_work_queue(&ctx->wake_utask);
break;
case RTSWITCH_RT:
case HECTIC_OOB_WAIT:
evl_raise_flag(&task->rt_synch);
break;
}
......@@ -103,7 +101,7 @@ static int rtswitch_pend_rt(struct rtswitch_context *ctx,
return -EINVAL;
task = &ctx->tasks[idx];
task->base.flags |= RTSWITCH_RT;
task->base.flags |= HECTIC_OOB_WAIT;
rc = evl_wait_flag(&task->rt_synch);
if (rc < 0)
......@@ -123,13 +121,13 @@ static void timed_wake_up(struct evl_timer *timer) /* hard irqs off */
ctx = container_of(timer, struct rtswitch_context, wake_up_delay);
task = &ctx->tasks[ctx->next_task];
switch (task->base.flags & RTSWITCH_RT) {
case RTSWITCH_NRT:
switch (task->base.flags & HECTIC_OOB_WAIT) {
case HECTIC_INBAND_WAIT:
ctx->utask = task;
irq_work_queue(&ctx->wake_utask);
break;
case RTSWITCH_RT:
case HECTIC_OOB_WAIT:
evl_raise_flag(&task->rt_synch);
}
}
......@@ -152,7 +150,7 @@ static int rtswitch_to_rt(struct rtswitch_context *ctx,
from = &ctx->tasks[from_idx];
to = &ctx->tasks[to_idx];
from->base.flags |= RTSWITCH_RT;
from->base.flags |= HECTIC_OOB_WAIT;
from->last_switch = ++ctx->switches_count;
ctx->error.last_switch.from = from_idx;
ctx->error.last_switch.to = to_idx;
......@@ -167,15 +165,15 @@ static int rtswitch_to_rt(struct rtswitch_context *ctx,
EVL_INFINITE);
evl_disable_preempt();
} else
switch (to->base.flags & RTSWITCH_RT) {
case RTSWITCH_NRT:
switch (to->base.flags & HECTIC_OOB_WAIT) {
case HECTIC_INBAND_WAIT:
ctx->utask = to;
barrier();
irq_work_queue(&ctx->wake_utask);
evl_disable_preempt();
break;
case RTSWITCH_RT:
case HECTIC_OOB_WAIT:
evl_disable_preempt();
evl_raise_flag(&to->rt_synch);
break;
......@@ -206,7 +204,7 @@ static int rtswitch_pend_nrt(struct rtswitch_context *ctx,
task = &ctx->tasks[idx];
task->base.flags &= ~RTSWITCH_RT;
task->base.flags &= ~HECTIC_OOB_WAIT;
if (down_interruptible(&task->nrt_synch))
return -EINTR;
......@@ -241,7 +239,7 @@ static int rtswitch_to_nrt(struct rtswitch_context *ctx,
&& ctx->error.last_switch.from == to_idx
&& ctx->error.last_switch.to == from_idx;
from->base.flags &= ~RTSWITCH_RT;
from->base.flags &= ~HECTIC_OOB_WAIT;
from->last_switch = ++ctx->switches_count;
ctx->error.last_switch.from = from_idx;
ctx->error.last_switch.to = to_idx;
......@@ -255,13 +253,13 @@ static int rtswitch_to_nrt(struct rtswitch_context *ctx,
ctx->pause_us * 1000),
EVL_INFINITE);
} else
switch (to->base.flags & RTSWITCH_RT) {
case RTSWITCH_NRT:
switch (to->base.flags & HECTIC_OOB_WAIT) {
case HECTIC_INBAND_WAIT:
switch_to_nrt:
up(&to->nrt_synch);
break;
case RTSWITCH_RT:
case HECTIC_OOB_WAIT:
if (!fp_check || !evl_begin_fpu())
goto signal_nofp;
......@@ -283,11 +281,11 @@ static int rtswitch_to_nrt(struct rtswitch_context *ctx,
return 1;
}
from->base.flags &= ~RTSWITCH_RT;
from->base.flags &= ~HECTIC_OOB_WAIT;
from->last_switch = ++ctx->switches_count;
ctx->error.last_switch.from = from_idx;
ctx->error.last_switch.to = to_idx;
if ((to->base.flags & RTSWITCH_RT) == RTSWITCH_NRT)
if ((to->base.flags & HECTIC_OOB_WAIT) == HECTIC_INBAND_WAIT)
goto switch_to_nrt;
expected = from_idx + 500 +
(ctx->switches_count % 4000000) * 1000;
......@@ -308,12 +306,12 @@ static int rtswitch_to_nrt(struct rtswitch_context *ctx,
return 1;
}
from->base.flags &= ~RTSWITCH_RT;
from->base.flags &= ~HECTIC_OOB_WAIT;
from->last_switch = ++ctx->switches_count;
ctx->error.last_switch.from = from_idx;
ctx->error.last_switch.to = to_idx;
barrier();
if ((to->base.flags & RTSWITCH_RT) == RTSWITCH_NRT)
if ((to->base.flags & HECTIC_OOB_WAIT) == HECTIC_INBAND_WAIT)
goto switch_to_nrt;
signal_nofp:
......@@ -360,7 +358,8 @@ static int rtswitch_set_tasks_count(struct rtswitch_context *ctx, unsigned int c
}
static int rtswitch_register_task(struct rtswitch_context *ctx,
struct hectic_task_index *arg)
struct hectic_task_index *arg,
int flags)
{
struct rtswitch_task *t;
......@@ -374,7 +373,8 @@ static int rtswitch_register_task(struct rtswitch_context *ctx,
arg->index = ctx->next_index;
t = &ctx->tasks[arg->index];
ctx->next_index++;
t->base = *arg;
t->base.index = arg->index;
t->base.flags = (arg->flags & HECTIC_OOB_WAIT)|flags;
t->last_switch = 0;
sema_init(&t->nrt_synch, 0);
evl_init_flag(&t->rt_synch);
......@@ -426,8 +426,7 @@ static int rtswitch_create_kthread(struct rtswitch_context *ctx,
struct rtswitch_task *task;
int err;
ptask->flags |= RTSWITCH_KERNEL;
err = rtswitch_register_task(ctx, ptask);
err = rtswitch_register_task(ctx, ptask, HECTIC_KTHREAD);
if (err)
return err;
......@@ -487,7 +486,7 @@ static long hectic_ioctl(struct file *filp, unsigned int cmd,
if (err)
return -EFAULT;
err = rtswitch_register_task(ctx, &task);
err = rtswitch_register_task(ctx, &task, 0);
if (!err && copy_to_user(u_task, &task, sizeof(task)))
err = -EFAULT;
......@@ -610,7 +609,7 @@ static int hectic_release(struct inode *inode, struct file *filp)
for (i = 0; i < ctx->next_index; i++) {
struct rtswitch_task *task = &ctx->tasks[i];
if (task->base.flags & RTSWITCH_KERNEL)
if (task->base.flags & HECTIC_KTHREAD)
evl_cancel_kthread(&task->kthread);
evl_destroy_flag(&task->rt_synch);
......
include/uapi/evl/devices/hectic.h
View file @ 1e413cc6
......@@ -9,6 +9,10 @@
#ifndef _EVL_UAPI_DEVICES_HECTIC_H
#define _EVL_UAPI_DEVICES_HECTIC_H
/* hectic_task_index.flags */
#define HECTIC_OOB_WAIT 0x10000
#define HECTIC_INBAND_WAIT 0
struct hectic_task_index {
unsigned int index;
unsigned int flags;
......
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