Revert "xen/events/fifo: Handle linked events when closing a port"

This change “Revert “xen/events/fifo: Handle linked events when closing a port”” in Linux kernel is authored by David Vrabel <david.vrabel [at] citrix.com> on Mon Aug 10 18:11:06 2015 +0100.

Revert "xen/events/fifo: Handle linked events when closing a port"

This reverts commit fcdf31a7c162de0c93a2bee51df4688ab0a348f8.

This was causing a WARNING whenever a PIRQ was closed since
shutdown_pirq() is called with irqs disabled.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: <stable@vger.kernel.org>

This Linux change may have been applied to various maintained Linux releases and you can find Linux releases including commit ad6cd7b.

There are 62 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 drivers/xen/events/events_base.c     | 10 ++++----
 drivers/xen/events/events_fifo.c     | 45 ++++--------------------------------
 drivers/xen/events/events_internal.h |  7 ------
 3 files changed, 9 insertions(+), 53 deletions(-)

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 1495ecc..96093ae 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -452,12 +452,10 @@ static void xen_free_irq(unsigned irq)
 	irq_free_desc(irq);
 }
 
-static void xen_evtchn_close(unsigned int port, unsigned int cpu)
+static void xen_evtchn_close(unsigned int port)
 {
 	struct evtchn_close close;
 
-	xen_evtchn_op_close(port, cpu);
-
 	close.port = port;
 	if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
 		BUG();
@@ -546,7 +544,7 @@ static unsigned int __startup_pirq(unsigned int irq)
 
 err:
 	pr_err("irq%d: Failed to set port to irq mapping (%d)n", irq, rc);
-	xen_evtchn_close(evtchn, NR_CPUS);
+	xen_evtchn_close(evtchn);
 	return 0;
 }
 
@@ -567,7 +565,7 @@ static void shutdown_pirq(struct irq_data *data)
 		return;
 
 	mask_evtchn(evtchn);
-	xen_evtchn_close(evtchn, cpu_from_evtchn(evtchn));
+	xen_evtchn_close(evtchn);
 	xen_irq_info_cleanup(info);
 }
 
@@ -611,7 +609,7 @@ static void __unbind_from_irq(unsigned int irq)
 	if (VALID_EVTCHN(evtchn)) {
 		unsigned int cpu = cpu_from_irq(irq);
 
-		xen_evtchn_close(evtchn, cpu);
+		xen_evtchn_close(evtchn);
 
 		switch (type_from_irq(irq)) {
 		case IRQT_VIRQ:
diff --git a/drivers/xen/events/events_fifo.c b/drivers/xen/events/events_fifo.c
index 6df8aac..ed673e1 100644
--- a/drivers/xen/events/events_fifo.c
+++ b/drivers/xen/events/events_fifo.c
@@ -255,12 +255,6 @@ static void evtchn_fifo_unmask(unsigned port)
 	}
 }
 
-static bool evtchn_fifo_is_linked(unsigned port)
-{
-	event_word_t *word = event_word_from_port(port);
-	return sync_test_bit(EVTCHN_FIFO_BIT(LINKED, word), BM(word));
-}
-
 static uint32_t clear_linked(volatile event_word_t *word)
 {
 	event_word_t new, old, w;
@@ -287,8 +281,7 @@ static void handle_irq_for_port(unsigned port)
 
 static void consume_one_event(unsigned cpu,
 			      struct evtchn_fifo_control_block *control_block,
-			      unsigned priority, unsigned long *ready,
-			      bool drop)
+			      unsigned priority, unsigned long *ready)
 {
 	struct evtchn_fifo_queue *q = &per_cpu(cpu_queue, cpu);
 	uint32_t head;
@@ -320,15 +313,13 @@ static void consume_one_event(unsigned cpu,
 	if (head == 0)
 		clear_bit(priority, ready);
 
-	if (evtchn_fifo_is_pending(port) && !evtchn_fifo_is_masked(port)) {
-		if (likely(!drop))
-			handle_irq_for_port(port);
-	}
+	if (evtchn_fifo_is_pending(port) && !evtchn_fifo_is_masked(port))
+		handle_irq_for_port(port);
 
 	q->head[priority] = head;
 }
 
-static void __evtchn_fifo_handle_events(unsigned cpu, bool drop)
+static void evtchn_fifo_handle_events(unsigned cpu)
 {
 	struct evtchn_fifo_control_block *control_block;
 	unsigned long ready;
@@ -340,16 +331,11 @@ static void __evtchn_fifo_handle_events(unsigned cpu, bool drop)
 
 	while (ready) {
 		q = find_first_bit(&ready, EVTCHN_FIFO_MAX_QUEUES);
-		consume_one_event(cpu, control_block, q, &ready, drop);
+		consume_one_event(cpu, control_block, q, &ready);
 		ready |= xchg(&control_block->ready, 0);
 	}
 }
 
-static void evtchn_fifo_handle_events(unsigned cpu)
-{
-	__evtchn_fifo_handle_events(cpu, false);
-}
-
 static void evtchn_fifo_resume(void)
 {
 	unsigned cpu;
@@ -385,26 +371,6 @@ static void evtchn_fifo_resume(void)
 	event_array_pages = 0;
 }
 
-static void evtchn_fifo_close(unsigned port, unsigned int cpu)
-{
-	if (cpu == NR_CPUS)
-		return;
-
-	get_online_cpus();
-	if (cpu_online(cpu)) {
-		if (WARN_ON(irqs_disabled()))
-			goto out;
-
-		while (evtchn_fifo_is_linked(port))
-			cpu_relax();
-	} else {
-		__evtchn_fifo_handle_events(cpu, true);
-	}
-
-out:
-	put_online_cpus();
-}
-
 static const struct evtchn_ops evtchn_ops_fifo = {
 	.max_channels      = evtchn_fifo_max_channels,
 	.nr_channels       = evtchn_fifo_nr_channels,
@@ -418,7 +384,6 @@ static void evtchn_fifo_close(unsigned port, unsigned int cpu)
 	.unmask            = evtchn_fifo_unmask,
 	.handle_events     = evtchn_fifo_handle_events,
 	.resume            = evtchn_fifo_resume,
-	.close             = evtchn_fifo_close,
 };
 
 static int evtchn_fifo_alloc_control_block(unsigned cpu)
diff --git a/drivers/xen/events/events_internal.h b/drivers/xen/events/events_internal.h
index d18e123..50c2050a 100644
--- a/drivers/xen/events/events_internal.h
+++ b/drivers/xen/events/events_internal.h
@@ -68,7 +68,6 @@ struct evtchn_ops {
 	bool (*test_and_set_mask)(unsigned port);
 	void (*mask)(unsigned port);
 	void (*unmask)(unsigned port);
-	void (*close)(unsigned port, unsigned cpu);
 
 	void (*handle_events)(unsigned cpu);
 	void (*resume)(void);
@@ -146,12 +145,6 @@ static inline void xen_evtchn_resume(void)
 		evtchn_ops->resume();
 }
 
-static inline void xen_evtchn_op_close(unsigned port, unsigned cpu)
-{
-	if (evtchn_ops->close)
-		return evtchn_ops->close(port, cpu);
-}
-
 void xen_evtchn_2l_init(void);
 int xen_evtchn_fifo_init(void);
 

The commit for this change in Linux stable tree is ad6cd7b (patch).

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