irq_work: Convert flags to atomic_t

We need to convert flags to atomic_t in order to later fix an ordering issue on atomic_cmpxchg() failure. This will allow us to use atomic_fetch_or(). Also clarify the nature of those flags. [ mingo: Converted two more usage site the original patch missed. ]

Frederic Weisbecker committed 7 years ago

Commit 153bedb1 parent 31f4f5b5 files · +19 −15Browse files

Unified · Split

5 files

include/linux/irq_work.h +7 −3
kernel/bpf/stackmap.c +1 −1
kernel/irq_work.c +9 −9
kernel/printk/printk.c +1 −1
kernel/trace/bpf_trace.c +1 −1

include/linux/irq_work.h+7−3

 #define IRQ_WORK_CLAIMED	(IRQ_WORK_PENDING | IRQ_WORK_BUSY)
 struct irq_work {
-	unsigned long flags;
+	atomic_t flags;
 	struct llist_node llnode;
 	void (*func)(struct irq_work *);
 };
 static inline
 void init_irq_work(struct irq_work *work, void (*func)(struct irq_work *))
 {
-	work->flags = 0;
+	atomic_set(&work->flags, 0);
 	work->func = func;
 }
-#define DEFINE_IRQ_WORK(name, _f) struct irq_work name = { .func = (_f), }
+#define DEFINE_IRQ_WORK(name, _f) struct irq_work name = {	\
+		.flags = ATOMIC_INIT(0),			\
+		.func  = (_f)					\
+}
 bool irq_work_queue(struct irq_work *work);
 bool irq_work_queue_on(struct irq_work *work, int cpu);

kernel/bpf/stackmap.c+1−1

@@ -289,7 +289,7 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs, · 288 unmodified lines
289		289
290	if (in_nmi()) {	290	if (in_nmi()) {
291	work = this_cpu_ptr(&up_read_work);	291	work = this_cpu_ptr(&up_read_work);
292	if (work->irq_work.flags & IRQ_WORK_BUSY)	292	if (atomic_read(&work->irq_work.flags) & IRQ_WORK_BUSY)
293	/* cannot queue more up_read, fallback */	293	/* cannot queue more up_read, fallback */
294	irq_work_busy = true;	294	irq_work_busy = true;
295	}	295	}

kernel/irq_work.c+9−9

@@ -29,16 +29,16 @@ static DEFINE_PER_CPU(struct llist_head, lazy_list); · 28 unmodified lines
29	*/	29	*/
30	static bool irq_work_claim(struct irq_work *work)	30	static bool irq_work_claim(struct irq_work *work)
31	{	31	{
32	unsigned long flags, oflags, nflags;	32	int flags, oflags, nflags;
33		33
34	/*	34	/*
35	* Start with our best wish as a premise but only trust any	35	* Start with our best wish as a premise but only trust any
36	* flag value after cmpxchg() result.	36	* flag value after cmpxchg() result.
37	*/	37	*/
38	flags = work->flags & ~IRQ_WORK_PENDING;	38	flags = atomic_read(&work->flags) & ~IRQ_WORK_PENDING;
39	for (;;) {	39	for (;;) {
40	nflags = flags \| IRQ_WORK_CLAIMED;	40	nflags = flags \| IRQ_WORK_CLAIMED;
41	oflags = cmpxchg(&work->flags, flags, nflags);	41	oflags = atomic_cmpxchg(&work->flags, flags, nflags);
42	if (oflags == flags)	42	if (oflags == flags)
43	break;	43	break;
44	if (oflags & IRQ_WORK_PENDING)	44	if (oflags & IRQ_WORK_PENDING)
@@ -61,7 +61,7 @@ void __weak arch_irq_work_raise(void) · 16 unmodified lines
61	static void __irq_work_queue_local(struct irq_work *work)	61	static void __irq_work_queue_local(struct irq_work *work)
62	{	62	{
63	/* If the work is "lazy", handle it from next tick if any */	63	/* If the work is "lazy", handle it from next tick if any */
64	if (work->flags & IRQ_WORK_LAZY) {	64	if (atomic_read(&work->flags) & IRQ_WORK_LAZY) {
65	if (llist_add(&work->llnode, this_cpu_ptr(&lazy_list)) &&	65	if (llist_add(&work->llnode, this_cpu_ptr(&lazy_list)) &&
66	tick_nohz_tick_stopped())	66	tick_nohz_tick_stopped())
67	arch_irq_work_raise();	67	arch_irq_work_raise();
@@ -143,7 +143,7 @@ static void irq_work_run_list(struct llist_head *list) · 75 unmodified lines
143	{	143	{
144	struct irq_work work, tmp;	144	struct irq_work work, tmp;
145	struct llist_node *llnode;	145	struct llist_node *llnode;
146	unsigned long flags;	146	int flags;
147		147
148	BUG_ON(!irqs_disabled());	148	BUG_ON(!irqs_disabled());
149		149
@@ -159,15 +159,15 @@ static void irq_work_run_list(struct llist_head *list) · 9 unmodified lines
159	* to claim that work don't rely on us to handle their data	159	* to claim that work don't rely on us to handle their data
160	* while we are in the middle of the func.	160	* while we are in the middle of the func.
161	*/	161	*/
162	flags = work->flags & ~IRQ_WORK_PENDING;	162	flags = atomic_read(&work->flags) & ~IRQ_WORK_PENDING;
163	xchg(&work->flags, flags);	163	atomic_xchg(&work->flags, flags);
164		164
165	work->func(work);	165	work->func(work);
166	/*	166	/*
167	* Clear the BUSY bit and return to the free state if	167	* Clear the BUSY bit and return to the free state if
168	* no-one else claimed it meanwhile.	168	* no-one else claimed it meanwhile.
169	*/	169	*/
170	(void)cmpxchg(&work->flags, flags, flags & ~IRQ_WORK_BUSY);	170	(void)atomic_cmpxchg(&work->flags, flags, flags & ~IRQ_WORK_BUSY);
171	}	171	}
172	}	172	}
173		173
@@ -199,7 +199,7 @@ void irq_work_sync(struct irq_work *work) · 25 unmodified lines
199	{	199	{
200	lockdep_assert_irqs_enabled();	200	lockdep_assert_irqs_enabled();
201		201
202	while (work->flags & IRQ_WORK_BUSY)	202	while (atomic_read(&work->flags) & IRQ_WORK_BUSY)
203	cpu_relax();	203	cpu_relax();
204	}	204	}
205	EXPORT_SYMBOL_GPL(irq_work_sync);	205	EXPORT_SYMBOL_GPL(irq_work_sync);

kernel/printk/printk.c+1−1

@@ -2961,7 +2961,7 @@ static void wake_up_klogd_work_func(struct irq_work *irq_work) · 2960 unmodified lines
2961		2961
2962	static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = {	2962	static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = {
2963	.func = wake_up_klogd_work_func,	2963	.func = wake_up_klogd_work_func,
2964	.flags = IRQ_WORK_LAZY,	2964	.flags = ATOMIC_INIT(IRQ_WORK_LAZY),
2965	};	2965	};
2966		2966
2967	void wake_up_klogd(void)	2967	void wake_up_klogd(void)

kernel/trace/bpf_trace.c+1−1

@@ -660,7 +660,7 @@ BPF_CALL_1(bpf_send_signal, u32, sig) · 659 unmodified lines
660	return -EINVAL;	660	return -EINVAL;
661		661
662	work = this_cpu_ptr(&send_signal_work);	662	work = this_cpu_ptr(&send_signal_work);
663	if (work->irq_work.flags & IRQ_WORK_BUSY)	663	if (atomic_read(&work->irq_work.flags) & IRQ_WORK_BUSY)
664	return -EBUSY;	664	return -EBUSY;
665		665
666	/* Add the current task, which is the target of sending signal,	666	/* Add the current task, which is the target of sending signal,

irq_work: Convert flags to atomic_t

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