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sched: Make migrate_disable/enable() independent of RT

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Now that the scheduler can deal with migrate disable properly, there is no
real compelling reason to make it only available for RT.

There are quite some code pathes which needlessly disable preemption in
order to prevent migration and some constructs like kmap_atomic() enforce
it implicitly.

Making it available independent of RT allows to provide a preemptible
variant of kmap_atomic() and makes the code more consistent in general.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Grudgingly-Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20201118204007.269943012@linutronix.de
This commit is contained in:
Thomas Gleixner
2020-11-24 11:25:44 +01:00
parent fa50e2b452
commit 74d862b682
6 changed files with 56 additions and 56 deletions
Download Patch File Download Diff File Expand all files Collapse all files
kernel/sched/core.c
+35 -10
View File
@@ -1728,8 +1728,6 @@ void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags)
#ifdef CONFIG_SMP
#ifdef CONFIG_PREEMPT_RT
static void
__do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask, u32 flags);
@@ -1800,8 +1798,6 @@ static inline bool rq_has_pinned_tasks(struct rq *rq)
return rq->nr_pinned;
}
#endif
/*
* Per-CPU kthreads are allowed to run on !active && online CPUs, see
* __set_cpus_allowed_ptr() and select_fallback_rq().
@@ -2882,7 +2878,7 @@ void sched_set_stop_task(int cpu, struct task_struct *stop)
}
}
#else
#else /* CONFIG_SMP */
static inline int __set_cpus_allowed_ptr(struct task_struct *p,
const struct cpumask *new_mask,
@@ -2891,10 +2887,6 @@ static inline int __set_cpus_allowed_ptr(struct task_struct *p,
return set_cpus_allowed_ptr(p, new_mask);
}
#endif /* CONFIG_SMP */
#if !defined(CONFIG_SMP) || !defined(CONFIG_PREEMPT_RT)
static inline void migrate_disable_switch(struct rq *rq, struct task_struct *p) { }
static inline bool rq_has_pinned_tasks(struct rq *rq)
@@ -2902,7 +2894,7 @@ static inline bool rq_has_pinned_tasks(struct rq *rq)
return false;
}
#endif
#endif /* !CONFIG_SMP */
static void
ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
@@ -7924,6 +7916,39 @@ void __cant_sleep(const char *file, int line, int preempt_offset)
add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
}
EXPORT_SYMBOL_GPL(__cant_sleep);
#ifdef CONFIG_SMP
void __cant_migrate(const char *file, int line)
{
static unsigned long prev_jiffy;
if (irqs_disabled())
return;
if (is_migration_disabled(current))
return;
if (!IS_ENABLED(CONFIG_PREEMPT_COUNT))
return;
if (preempt_count() > 0)
return;
if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
return;
prev_jiffy = jiffies;
pr_err("BUG: assuming non migratable context at %s:%d\n", file, line);
pr_err("in_atomic(): %d, irqs_disabled(): %d, migration_disabled() %u pid: %d, name: %s\n",
in_atomic(), irqs_disabled(), is_migration_disabled(current),
current->pid, current->comm);
debug_show_held_locks(current);
dump_stack();
add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
}
EXPORT_SYMBOL_GPL(__cant_migrate);
#endif
#endif
#ifdef CONFIG_MAGIC_SYSRQ
kernel/sched/sched.h
+2 -2
View File
@@ -1056,7 +1056,7 @@ struct rq {
struct cpuidle_state *idle_state;
#endif
#if defined(CONFIG_PREEMPT_RT) && defined(CONFIG_SMP)
#ifdef CONFIG_SMP
unsigned int nr_pinned;
#endif
unsigned int push_busy;
@@ -1092,7 +1092,7 @@ static inline int cpu_of(struct rq *rq)
static inline bool is_migration_disabled(struct task_struct *p)
{
#if defined(CONFIG_SMP) && defined(CONFIG_PREEMPT_RT)
#ifdef CONFIG_SMP
return p->migration_disabled;
#else
return false;