[RFC][PATCH 1/9] irq_work: Cleanup

Peter Zijlstra
2020-07-22T15:33:20Z

Get rid of the __call_single_node union and clean up the API a little
to avoid external code relying on the structure layout as much.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
drivers/gpu/drm/i915/i915_request.c | 4 ++--
include/linux/irq_work.h | 33 +++++++++++++++++++++------------
include/linux/irqflags.h | 4 ++--
kernel/bpf/stackmap.c | 2 +-
kernel/irq_work.c | 18 +++++++++---------
kernel/printk/printk.c | 6 ++----
kernel/rcu/tree.c | 3 +--
kernel/time/tick-sched.c | 6 ++----
kernel/trace/bpf_trace.c | 2 +-
9 files changed, 41 insertions(+), 37 deletions(-)

--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -196,7 +196,7 @@ __notify_execute_cb(struct i915_request

llist_for_each_entry_safe(cb, cn,
llist_del_all(&rq->execute_cb),
- work.llnode)
+ work.node.llist)
fn(&cb->work);
}

@@ -478,7 +478,7 @@ __await_execution(struct i915_request *r
* callback first, then checking the ACTIVE bit, we serialise with
* the completed/retired request.
*/
- if (llist_add(&cb->work.llnode, &signal->execute_cb)) {
+ if (llist_add(&cb->work.node.llist, &signal->execute_cb)) {
if (i915_request_is_active(signal) ||
__request_in_flight(signal))
__notify_execute_cb_imm(signal);
--- a/include/linux/irq_work.h
+++ b/include/linux/irq_work.h
@@ -14,28 +14,37 @@
*/

struct irq_work {
- union {
- struct __call_single_node node;
- struct {
- struct llist_node llnode;
- atomic_t flags;
- };
- };
+ struct __call_single_node node;
void (*func)(struct irq_work *);
};

+#define __IRQ_WORK_INIT(_func, _flags) (struct irq_work){ \
+ .node = { .u_flags = (_flags), }, \
+ .func = (_func), \
+}
+
+#define IRQ_WORK_INIT(_func) __IRQ_WORK_INIT(_func, 0)
+#define IRQ_WORK_INIT_LAZY(_func) __IRQ_WORK_INIT(_func, IRQ_WORK_LAZY)
+#define IRQ_WORK_INIT_HARD(_func) __IRQ_WORK_INIT(_func, IRQ_WORK_HARD_IRQ)
+
+#define DEFINE_IRQ_WORK(name, _f) \
+ struct irq_work name = IRQ_WORK_INIT(_f)
+
static inline
void init_irq_work(struct irq_work *work, void (*func)(struct irq_work *))
{
- atomic_set(&work->flags, 0);
- work->func = func;
+ *work = IRQ_WORK_INIT(func);
}

-#define DEFINE_IRQ_WORK(name, _f) struct irq_work name = { \
- .flags = ATOMIC_INIT(0), \
- .func = (_f) \
+static inline bool irq_work_is_pending(struct irq_work *work)
+{
+ return atomic_read(&work->node.a_flags) & IRQ_WORK_PENDING;
}

+static inline bool irq_work_is_busy(struct irq_work *work)
+{
+ return atomic_read(&work->node.a_flags) & IRQ_WORK_BUSY;
+}

bool irq_work_queue(struct irq_work *work);
bool irq_work_queue_on(struct irq_work *work, int cpu);
--- a/include/linux/irqflags.h
+++ b/include/linux/irqflags.h
@@ -95,12 +95,12 @@ do { \

# define lockdep_irq_work_enter(__work) \
do { \
- if (!(atomic_read(&__work->flags) & IRQ_WORK_HARD_IRQ))\
+ if (!(atomic_read(&__work->node.a_flags) & IRQ_WORK_HARD_IRQ))\
current->irq_config = 1; \
} while (0)
# define lockdep_irq_work_exit(__work) \
do { \
- if (!(atomic_read(&__work->flags) & IRQ_WORK_HARD_IRQ))\
+ if (!(atomic_read(&__work->node.a_flags) & IRQ_WORK_HARD_IRQ))\
current->irq_config = 0; \
} while (0)

--- a/kernel/bpf/stackmap.c
+++ b/kernel/bpf/stackmap.c
@@ -293,7 +293,7 @@ static void stack_map_get_build_id_offse
if (irqs_disabled()) {
if (!IS_ENABLED(CONFIG_PREEMPT_RT)) {
work = this_cpu_ptr(&up_read_work);
- if (atomic_read(&work->irq_work.flags) & IRQ_WORK_BUSY) {
+ if (irq_work_is_busy(&work->irq_work)) {
/* cannot queue more up_read, fallback */
irq_work_busy = true;
}
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -31,7 +31,7 @@ static bool irq_work_claim(struct irq_wo
{
int oflags;

- oflags = atomic_fetch_or(IRQ_WORK_CLAIMED | CSD_TYPE_IRQ_WORK, &work->flags);
+ oflags = atomic_fetch_or(IRQ_WORK_CLAIMED | CSD_TYPE_IRQ_WORK, &work->node.a_flags);
/*
* If the work is already pending, no need to raise the IPI.
* The pairing atomic_fetch_andnot() in irq_work_run() makes sure
@@ -53,12 +53,12 @@ void __weak arch_irq_work_raise(void)
static void __irq_work_queue_local(struct irq_work *work)
{
/* If the work is "lazy", handle it from next tick if any */
- if (atomic_read(&work->flags) & IRQ_WORK_LAZY) {
- if (llist_add(&work->llnode, this_cpu_ptr(&lazy_list)) &&
+ if (atomic_read(&work->node.a_flags) & IRQ_WORK_LAZY) {
+ if (llist_add(&work->node.llist, this_cpu_ptr(&lazy_list)) &&
tick_nohz_tick_stopped())
arch_irq_work_raise();
} else {
- if (llist_add(&work->llnode, this_cpu_ptr(&raised_list)))
+ if (llist_add(&work->node.llist, this_cpu_ptr(&raised_list)))
arch_irq_work_raise();
}
}
@@ -102,7 +102,7 @@ bool irq_work_queue_on(struct irq_work *
if (cpu != smp_processor_id()) {
/* Arch remote IPI send/receive backend aren't NMI safe */
WARN_ON_ONCE(in_nmi());
- __smp_call_single_queue(cpu, &work->llnode);
+ __smp_call_single_queue(cpu, &work->node.llist);
} else {
__irq_work_queue_local(work);
}
@@ -142,7 +142,7 @@ void irq_work_single(void *arg)
* to claim that work don't rely on us to handle their data
* while we are in the middle of the func.
*/
- flags = atomic_fetch_andnot(IRQ_WORK_PENDING, &work->flags);
+ flags = atomic_fetch_andnot(IRQ_WORK_PENDING, &work->node.a_flags);

lockdep_irq_work_enter(work);
work->func(work);
@@ -152,7 +152,7 @@ void irq_work_single(void *arg)
* no-one else claimed it meanwhile.
*/
flags &= ~IRQ_WORK_PENDING;
- (void)atomic_cmpxchg(&work->flags, flags, flags & ~IRQ_WORK_BUSY);
+ (void)atomic_cmpxchg(&work->node.a_flags, flags, flags & ~IRQ_WORK_BUSY);
}

static void irq_work_run_list(struct llist_head *list)
@@ -166,7 +166,7 @@ static void irq_work_run_list(struct lli
return;

llnode = llist_del_all(list);
- llist_for_each_entry_safe(work, tmp, llnode, llnode)
+ llist_for_each_entry_safe(work, tmp, llnode, node.llist)
irq_work_single(work);
}

@@ -198,7 +198,7 @@ void irq_work_sync(struct irq_work *work
{
lockdep_assert_irqs_enabled();

- while (atomic_read(&work->flags) & IRQ_WORK_BUSY)
+ while (irq_work_is_busy(work))
cpu_relax();
}
EXPORT_SYMBOL_GPL(irq_work_sync);
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3068,10 +3068,8 @@ static void wake_up_klogd_work_func(stru
wake_up_interruptible(&log_wait);
}

-static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = {
- .func = wake_up_klogd_work_func,
- .flags = ATOMIC_INIT(IRQ_WORK_LAZY),
-};
+static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) =
+ IRQ_WORK_INIT_LAZY(wake_up_klogd_work_func);

void wake_up_klogd(void)
{
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1287,8 +1287,6 @@ static int rcu_implicit_dynticks_qs(stru
if (IS_ENABLED(CONFIG_IRQ_WORK) &&
!rdp->rcu_iw_pending && rdp->rcu_iw_gp_seq != rnp->gp_seq &&
(rnp->ffmask & rdp->grpmask)) {
- init_irq_work(&rdp->rcu_iw, rcu_iw_handler);
- atomic_set(&rdp->rcu_iw.flags, IRQ_WORK_HARD_IRQ);
rdp->rcu_iw_pending = true;
rdp->rcu_iw_gp_seq = rnp->gp_seq;
irq_work_queue_on(&rdp->rcu_iw, rdp->cpu);
@@ -3895,6 +3893,7 @@ int rcutree_prepare_cpu(unsigned int cpu
rdp->cpu_no_qs.b.norm = true;
rdp->core_needs_qs = false;
rdp->rcu_iw_pending = false;
+ rdp->rcu_iw = IRQ_WORK_INIT_HARD(rcu_iw_handler);
rdp->rcu_iw_gp_seq = rdp->gp_seq - 1;
trace_rcu_grace_period(rcu_state.name, rdp->gp_seq, TPS("cpuonl"));
raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -243,10 +243,8 @@ static void nohz_full_kick_func(struct i
/* Empty, the tick restart happens on tick_nohz_irq_exit() */
}

-static DEFINE_PER_CPU(struct irq_work, nohz_full_kick_work) = {
- .func = nohz_full_kick_func,
- .flags = ATOMIC_INIT(IRQ_WORK_HARD_IRQ),
-};
+static DEFINE_PER_CPU(struct irq_work, nohz_full_kick_work) =
+ IRQ_WORK_INIT_HARD(nohz_full_kick_func);

/*
* Kick this CPU if it's full dynticks in order to force it to
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1057,7 +1057,7 @@ static int bpf_send_signal_common(u32 si
return -EINVAL;

work = this_cpu_ptr(&send_signal_work);
- if (atomic_read(&work->irq_work.flags) & IRQ_WORK_BUSY)
+ if (irq_work_is_busy(&work->irq_work))
return -EBUSY;

/* Add the current task, which is the target of sending signal,