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context_tracking: Convert state to atomic_t

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Context tracking's state and dynticks counter are going to be merged
in a single field so that both updates can happen atomically and at the
same time. Prepare for that with converting the state into an atomic_t.

[ paulmck: Apply kernel test robot feedback. ]

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
This commit is contained in:
Frederic Weisbecker
2022-06-08 16:40:35 +02:00
committed by Paul E. McKenney
parent c33ef43a35
commit 171476775d
5 changed files with 159 additions and 92 deletions
Download Patch File Download Diff File Expand all files Collapse all files

59
include/linux/context_tracking_state.h
View File

@@ -6,16 +6,24 @@
#include <linux/static_key.h>
#include <linux/context_tracking_irq.h>
enum ctx_state {
CONTEXT_DISABLED = -1, /* returned by ct_state() if unknown */
CONTEXT_KERNEL = 0,
CONTEXT_USER,
CONTEXT_GUEST,
};
/* Offset to allow distinguishing irq vs. task-based idle entry/exit. */
#define DYNTICK_IRQ_NONIDLE ((LONG_MAX / 2) + 1)
enum ctx_state {
CONTEXT_DISABLED = -1, /* returned by ct_state() if unknown */
CONTEXT_KERNEL = 0,
CONTEXT_IDLE = 1,
CONTEXT_USER = 2,
CONTEXT_GUEST = 3,
CONTEXT_MAX = 4,
};
/* Even value for idle, else odd. */
#define RCU_DYNTICKS_IDX CONTEXT_MAX
#define CT_STATE_MASK (CONTEXT_MAX - 1)
#define CT_DYNTICKS_MASK (~CT_STATE_MASK)
struct context_tracking {
#ifdef CONFIG_CONTEXT_TRACKING_USER
/*
@@ -26,10 +34,11 @@ struct context_tracking {
*/
bool active;
int recursion;
enum ctx_state state;
#endif
#ifdef CONFIG_CONTEXT_TRACKING
atomic_t state;
#endif
#ifdef CONFIG_CONTEXT_TRACKING_IDLE
atomic_t dynticks; /* Even value for idle, else odd. */
long dynticks_nesting; /* Track process nesting level. */
long dynticks_nmi_nesting; /* Track irq/NMI nesting level. */
#endif
@@ -37,26 +46,31 @@ struct context_tracking {
#ifdef CONFIG_CONTEXT_TRACKING
DECLARE_PER_CPU(struct context_tracking, context_tracking);
static __always_inline int __ct_state(void)
{
return atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_STATE_MASK;
}
#endif
#ifdef CONFIG_CONTEXT_TRACKING_IDLE
static __always_inline int ct_dynticks(void)
{
return atomic_read(this_cpu_ptr(&context_tracking.dynticks));
return atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_DYNTICKS_MASK;
}
static __always_inline int ct_dynticks_cpu(int cpu)
{
struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
return atomic_read(&ct->dynticks);
return atomic_read(&ct->state) & CT_DYNTICKS_MASK;
}
static __always_inline int ct_dynticks_cpu_acquire(int cpu)
{
struct context_tracking *ct = per_cpu_ptr(&context_tracking, cpu);
return atomic_read_acquire(&ct->dynticks);
return atomic_read_acquire(&ct->state) & CT_DYNTICKS_MASK;
}
static __always_inline long ct_dynticks_nesting(void)
@@ -102,6 +116,27 @@ static inline bool context_tracking_enabled_this_cpu(void)
return context_tracking_enabled() && __this_cpu_read(context_tracking.active);
}
/**
* ct_state() - return the current context tracking state if known
*
* Returns the current cpu's context tracking state if context tracking
* is enabled. If context tracking is disabled, returns
* CONTEXT_DISABLED. This should be used primarily for debugging.
*/
static __always_inline int ct_state(void)
{
int ret;
if (!context_tracking_enabled())
return CONTEXT_DISABLED;
preempt_disable();
ret = __ct_state();
preempt_enable();
return ret;
}
#else
static __always_inline bool context_tracking_enabled(void) { return false; }
static __always_inline bool context_tracking_enabled_cpu(int cpu) { return false; }