From: Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
To: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Cc: Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>,
George Dunlap <george.dunlap@citrix.com>,
Dario Faggioli <dfaggioli@suse.com>
Subject: [RFC PATCH 01/10] sched: core: save IRQ state during locking
Date: Tue, 23 Feb 2021 02:34:55 +0000 [thread overview]
Message-ID: <20210223023428.757694-2-volodymyr_babchuk@epam.com> (raw)
In-Reply-To: <20210223023428.757694-1-volodymyr_babchuk@epam.com>
With XEN preemption enabled, scheduler functions can be called with
IRQs disabled (for example, at end of IRQ handler), so we should
save and restore IRQ state in schedulers code.
Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@epam.com>
---
xen/common/sched/core.c | 33 ++++++++++++++++++---------------
1 file changed, 18 insertions(+), 15 deletions(-)
diff --git a/xen/common/sched/core.c b/xen/common/sched/core.c
index 9745a77eee..7e075613d5 100644
--- a/xen/common/sched/core.c
+++ b/xen/common/sched/core.c
@@ -2470,7 +2470,8 @@ static struct vcpu *sched_force_context_switch(struct vcpu *vprev,
* sched_res_rculock has been dropped.
*/
static struct sched_unit *sched_wait_rendezvous_in(struct sched_unit *prev,
- spinlock_t **lock, int cpu,
+ spinlock_t **lock,
+ unsigned long *flags, int cpu,
s_time_t now)
{
struct sched_unit *next;
@@ -2500,7 +2501,7 @@ static struct sched_unit *sched_wait_rendezvous_in(struct sched_unit *prev,
prev->rendezvous_in_cnt++;
atomic_set(&prev->rendezvous_out_cnt, 0);
- pcpu_schedule_unlock_irq(*lock, cpu);
+ pcpu_schedule_unlock_irqrestore(*lock, *flags, cpu);
sched_context_switch(vprev, v, false, now);
@@ -2530,7 +2531,7 @@ static struct sched_unit *sched_wait_rendezvous_in(struct sched_unit *prev,
prev->rendezvous_in_cnt++;
atomic_set(&prev->rendezvous_out_cnt, 0);
- pcpu_schedule_unlock_irq(*lock, cpu);
+ pcpu_schedule_unlock_irqrestore(*lock, *flags, cpu);
raise_softirq(SCHED_SLAVE_SOFTIRQ);
sched_context_switch(vprev, vprev, false, now);
@@ -2538,11 +2539,11 @@ static struct sched_unit *sched_wait_rendezvous_in(struct sched_unit *prev,
return NULL; /* ARM only. */
}
- pcpu_schedule_unlock_irq(*lock, cpu);
+ pcpu_schedule_unlock_irqrestore(*lock, *flags, cpu);
cpu_relax();
- *lock = pcpu_schedule_lock_irq(cpu);
+ *lock = pcpu_schedule_lock_irqsave(cpu, flags);
/*
* Check for scheduling resource switched. This happens when we are
@@ -2557,7 +2558,7 @@ static struct sched_unit *sched_wait_rendezvous_in(struct sched_unit *prev,
ASSERT(is_idle_unit(prev));
atomic_set(&prev->next_task->rendezvous_out_cnt, 0);
prev->rendezvous_in_cnt = 0;
- pcpu_schedule_unlock_irq(*lock, cpu);
+ pcpu_schedule_unlock_irqrestore(*lock, *flags, cpu);
rcu_read_unlock(&sched_res_rculock);
return NULL;
}
@@ -2574,12 +2575,13 @@ static void sched_slave(void)
spinlock_t *lock;
bool do_softirq = false;
unsigned int cpu = smp_processor_id();
+ unsigned long flags;
ASSERT_NOT_IN_ATOMIC();
rcu_read_lock(&sched_res_rculock);
- lock = pcpu_schedule_lock_irq(cpu);
+ lock = pcpu_schedule_lock_irqsave(cpu, &flags);
now = NOW();
@@ -2590,7 +2592,7 @@ static void sched_slave(void)
if ( v )
{
- pcpu_schedule_unlock_irq(lock, cpu);
+ pcpu_schedule_unlock_irqrestore(lock, flags, cpu);
sched_context_switch(vprev, v, false, now);
@@ -2602,7 +2604,7 @@ static void sched_slave(void)
if ( !prev->rendezvous_in_cnt )
{
- pcpu_schedule_unlock_irq(lock, cpu);
+ pcpu_schedule_unlock_irqrestore(lock, flags, cpu);
rcu_read_unlock(&sched_res_rculock);
@@ -2615,11 +2617,11 @@ static void sched_slave(void)
stop_timer(&get_sched_res(cpu)->s_timer);
- next = sched_wait_rendezvous_in(prev, &lock, cpu, now);
+ next = sched_wait_rendezvous_in(prev, &lock, &flags, cpu, now);
if ( !next )
return;
- pcpu_schedule_unlock_irq(lock, cpu);
+ pcpu_schedule_unlock_irqrestore(lock, flags, cpu);
sched_context_switch(vprev, sched_unit2vcpu_cpu(next, cpu),
is_idle_unit(next) && !is_idle_unit(prev), now);
@@ -2637,6 +2639,7 @@ static void schedule(void)
s_time_t now;
struct sched_resource *sr;
spinlock_t *lock;
+ unsigned long flags;
int cpu = smp_processor_id();
unsigned int gran;
@@ -2646,7 +2649,7 @@ static void schedule(void)
rcu_read_lock(&sched_res_rculock);
- lock = pcpu_schedule_lock_irq(cpu);
+ lock = pcpu_schedule_lock_irqsave(cpu, &flags);
sr = get_sched_res(cpu);
gran = sr->granularity;
@@ -2657,7 +2660,7 @@ static void schedule(void)
* We have a race: sched_slave() should be called, so raise a softirq
* in order to re-enter schedule() later and call sched_slave() now.
*/
- pcpu_schedule_unlock_irq(lock, cpu);
+ pcpu_schedule_unlock_irqrestore(lock, flags, cpu);
rcu_read_unlock(&sched_res_rculock);
@@ -2676,7 +2679,7 @@ static void schedule(void)
prev->rendezvous_in_cnt = gran;
cpumask_andnot(mask, sr->cpus, cpumask_of(cpu));
cpumask_raise_softirq(mask, SCHED_SLAVE_SOFTIRQ);
- next = sched_wait_rendezvous_in(prev, &lock, cpu, now);
+ next = sched_wait_rendezvous_in(prev, &lock, &flags, cpu, now);
if ( !next )
return;
}
@@ -2687,7 +2690,7 @@ static void schedule(void)
atomic_set(&next->rendezvous_out_cnt, 0);
}
- pcpu_schedule_unlock_irq(lock, cpu);
+ pcpu_schedule_unlock_irqrestore(lock, flags, cpu);
vnext = sched_unit2vcpu_cpu(next, cpu);
sched_context_switch(vprev, vnext,
--
2.29.2
next prev parent reply other threads:[~2021-02-23 2:35 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-23 2:34 [RFC PATCH 00/10] Preemption in hypervisor (ARM only) Volodymyr Babchuk
2021-02-23 2:34 ` Volodymyr Babchuk [this message]
2021-02-23 8:52 ` [RFC PATCH 01/10] sched: core: save IRQ state during locking Jürgen Groß
2021-02-23 11:15 ` Volodymyr Babchuk
2021-02-24 18:29 ` Andrew Cooper
2021-02-23 2:34 ` [RFC PATCH 03/10] sched: credit2: " Volodymyr Babchuk
2021-02-23 2:34 ` [RFC PATCH 02/10] sched: rt: " Volodymyr Babchuk
2021-02-23 2:34 ` [RFC PATCH 04/10] preempt: use atomic_t to for preempt_count Volodymyr Babchuk
2021-02-23 2:34 ` [RFC PATCH 05/10] preempt: add try_preempt() function Volodymyr Babchuk
2021-02-23 2:34 ` [RFC PATCH 07/10] sched: core: remove ASSERT_NOT_IN_ATOMIC and disable preemption[!] Volodymyr Babchuk
2021-02-23 2:34 ` [RFC PATCH 06/10] arm: setup: disable preemption during startup Volodymyr Babchuk
2021-02-23 2:34 ` [RFC PATCH 08/10] arm: context_switch: allow to run with IRQs already disabled Volodymyr Babchuk
2021-02-23 2:34 ` [RFC PATCH 10/10] [HACK] alloc pages: enable preemption early Volodymyr Babchuk
2021-02-23 2:34 ` [RFC PATCH 09/10] arm: traps: try to preempt before leaving IRQ handler Volodymyr Babchuk
2021-02-23 9:02 ` [RFC PATCH 00/10] Preemption in hypervisor (ARM only) Julien Grall
2021-02-23 12:06 ` Volodymyr Babchuk
2021-02-24 10:08 ` Julien Grall
2021-02-24 20:57 ` Volodymyr Babchuk
2021-02-24 22:31 ` Julien Grall
2021-02-24 23:58 ` Volodymyr Babchuk
2021-02-25 0:39 ` Andrew Cooper
2021-02-25 12:51 ` Volodymyr Babchuk
2021-03-05 9:31 ` Volodymyr Babchuk
2021-02-24 18:07 ` Andrew Cooper
2021-02-24 23:37 ` Volodymyr Babchuk
2021-03-01 14:39 ` George Dunlap
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