patches/net-iwlwifi-request-only-a-threaded-handler-for-inte.patch

From 71a040bb37b815d4d4a2be8ab2a14b9c41e3fc19 Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Fri, 4 Oct 2013 11:42:34 +0200
Subject: [PATCH] net: iwlwifi: request only a threaded handler for
 interrupts

On RT the trans_pcie->irq_lock lock is converted into a sleeping lock
and can't be used in primary irq handler. The lock is used in mutliple
places which means turning it into a raw lock could increase the
latency of the system.
For now both handlers are moved into the thread.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/net/wireless/iwlwifi/pcie/trans.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/net/wireless/iwlwifi/pcie/trans.c b/drivers/net/wireless/iwlwifi/pcie/trans.c
index aeb70e1..42567fc 100644
--- a/drivers/net/wireless/iwlwifi/pcie/trans.c
+++ b/drivers/net/wireless/iwlwifi/pcie/trans.c
@@ -1456,6 +1456,20 @@ static const struct iwl_trans_ops trans_ops_pcie = {
 	.set_bits_mask = iwl_trans_pcie_set_bits_mask,
 };
 
+#ifdef CONFIG_PREEMPT_RT_BASE
+static irqreturn_t iwl_rt_irq_handler(int irq, void *dev_id)
+{
+	irqreturn_t ret;
+
+	local_bh_disable();
+	ret = iwl_pcie_isr_ict(irq, dev_id);
+	local_bh_enable();
+	if (ret == IRQ_WAKE_THREAD)
+		ret = iwl_pcie_irq_handler(irq, dev_id);
+	return ret;
+}
+#endif
+
 struct iwl_trans *iwl_trans_pcie_alloc(struct pci_dev *pdev,
 				       const struct pci_device_id *ent,
 				       const struct iwl_cfg *cfg)
@@ -1566,9 +1580,14 @@ struct iwl_trans *iwl_trans_pcie_alloc(struct pci_dev *pdev,
 	if (iwl_pcie_alloc_ict(trans))
 		goto out_free_cmd_pool;
 
+#ifdef CONFIG_PREEMPT_RT_BASE
+	if (request_threaded_irq(pdev->irq, NULL, iwl_rt_irq_handler,
+				 IRQF_SHARED | IRQF_ONESHOT, DRV_NAME, trans)) {
+#else
 	if (request_threaded_irq(pdev->irq, iwl_pcie_isr_ict,
 				 iwl_pcie_irq_handler,
 				 IRQF_SHARED, DRV_NAME, trans)) {
+#endif
 		IWL_ERR(trans, "Error allocating IRQ %d\n", pdev->irq);
 		goto out_free_ict;
 	}
-- 
1.8.4.rc3