[ANNOUNCE] v5.10.14-rt28

[ANNOUNCE] v5.10.14-rt28

[Sebastian Andrzej Siewior]

Dear RT folks!

I'm pleased to announce the v5.10.14-rt28 patch set. 

Changes since v5.10.14-rt27:

  - Lazy preemption fix for 64bit PowerPC. It was broken since
    v5.9-rc2-rt1. Reported by John Ogness.

  - Two patches for chelsio/cxgb network driver to avoid
    tasklet_disable() usage in atomic context on !RT.

Known issues
     - kdb/kgdb can easily deadlock.
     - kmsg dumpers expecting not to be called in parallel can clobber
       their temp buffer.
     - netconsole triggers WARN.

The delta patch against v5.10.14-rt27 is appended below and can be found here:
 
     https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.10/incr/patch-5.10.14-rt27-rt28.patch.xz

You can get this release via the git tree at:

    git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git v5.10.14-rt28

The RT patch against v5.10.14 can be found here:

    https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patch-5.10.14-rt28.patch.xz

The split quilt queue is available at:

    https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.14-rt28.tar.xz

Sebastian

diff --git a/arch/powerpc/kernel/syscall_64.c b/arch/powerpc/kernel/syscall_64.c
index 70c8e9bda1f6c..ae3212dcf5627 100644
--- a/arch/powerpc/kernel/syscall_64.c
+++ b/arch/powerpc/kernel/syscall_64.c
@@ -367,7 +367,8 @@ notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs, unsign
 				if (preempt_count() == 0)
 					preempt_schedule_irq();
 			} else if (unlikely(*ti_flagsp & _TIF_NEED_RESCHED_LAZY)) {
-				if (current_thread_info()->preempt_lazy_count == 0)
+				if ((preempt_count() == 0) &&
+				    (current_thread_info()->preempt_lazy_count == 0))
 					preempt_schedule_irq();
 			}
 		}
diff --git a/drivers/net/ethernet/chelsio/cxgb/common.h b/drivers/net/ethernet/chelsio/cxgb/common.h
index 6475060649e90..0321be77366c4 100644
--- a/drivers/net/ethernet/chelsio/cxgb/common.h
+++ b/drivers/net/ethernet/chelsio/cxgb/common.h
@@ -238,7 +238,6 @@ struct adapter {
 	int msg_enable;
 	u32 mmio_len;
 
-	struct work_struct ext_intr_handler_task;
 	struct adapter_params params;
 
 	/* Terminator modules. */
@@ -257,6 +256,7 @@ struct adapter {
 
 	/* guards async operations */
 	spinlock_t async_lock ____cacheline_aligned;
+	u32 pending_thread_intr;
 	u32 slow_intr_mask;
 	int t1powersave;
 };
@@ -334,8 +334,7 @@ void t1_interrupts_enable(adapter_t *adapter);
 void t1_interrupts_disable(adapter_t *adapter);
 void t1_interrupts_clear(adapter_t *adapter);
 int t1_elmer0_ext_intr_handler(adapter_t *adapter);
-void t1_elmer0_ext_intr(adapter_t *adapter);
-int t1_slow_intr_handler(adapter_t *adapter);
+irqreturn_t t1_slow_intr_handler(adapter_t *adapter);
 
 int t1_link_start(struct cphy *phy, struct cmac *mac, struct link_config *lc);
 const struct board_info *t1_get_board_info(unsigned int board_id);
@@ -347,7 +346,6 @@ int t1_get_board_rev(adapter_t *adapter, const struct board_info *bi,
 int t1_init_hw_modules(adapter_t *adapter);
 int t1_init_sw_modules(adapter_t *adapter, const struct board_info *bi);
 void t1_free_sw_modules(adapter_t *adapter);
-void t1_fatal_err(adapter_t *adapter);
 void t1_link_changed(adapter_t *adapter, int port_id);
 void t1_link_negotiated(adapter_t *adapter, int port_id, int link_stat,
 			    int speed, int duplex, int pause);
diff --git a/drivers/net/ethernet/chelsio/cxgb/cxgb2.c b/drivers/net/ethernet/chelsio/cxgb/cxgb2.c
index 0e4a0f413960a..512da98019c66 100644
--- a/drivers/net/ethernet/chelsio/cxgb/cxgb2.c
+++ b/drivers/net/ethernet/chelsio/cxgb/cxgb2.c
@@ -211,9 +211,10 @@ static int cxgb_up(struct adapter *adapter)
 	t1_interrupts_clear(adapter);
 
 	adapter->params.has_msi = !disable_msi && !pci_enable_msi(adapter->pdev);
-	err = request_irq(adapter->pdev->irq, t1_interrupt,
-			  adapter->params.has_msi ? 0 : IRQF_SHARED,
-			  adapter->name, adapter);
+	err = request_threaded_irq(adapter->pdev->irq, t1_interrupt,
+				   t1_interrupt_thread,
+				   adapter->params.has_msi ? 0 : IRQF_SHARED,
+				   adapter->name, adapter);
 	if (err) {
 		if (adapter->params.has_msi)
 			pci_disable_msi(adapter->pdev);
@@ -916,51 +917,6 @@ static void mac_stats_task(struct work_struct *work)
 	spin_unlock(&adapter->work_lock);
 }
 
-/*
- * Processes elmer0 external interrupts in process context.
- */
-static void ext_intr_task(struct work_struct *work)
-{
-	struct adapter *adapter =
-		container_of(work, struct adapter, ext_intr_handler_task);
-
-	t1_elmer0_ext_intr_handler(adapter);
-
-	/* Now reenable external interrupts */
-	spin_lock_irq(&adapter->async_lock);
-	adapter->slow_intr_mask |= F_PL_INTR_EXT;
-	writel(F_PL_INTR_EXT, adapter->regs + A_PL_CAUSE);
-	writel(adapter->slow_intr_mask | F_PL_INTR_SGE_DATA,
-		   adapter->regs + A_PL_ENABLE);
-	spin_unlock_irq(&adapter->async_lock);
-}
-
-/*
- * Interrupt-context handler for elmer0 external interrupts.
- */
-void t1_elmer0_ext_intr(struct adapter *adapter)
-{
-	/*
-	 * Schedule a task to handle external interrupts as we require
-	 * a process context.  We disable EXT interrupts in the interim
-	 * and let the task reenable them when it's done.
-	 */
-	adapter->slow_intr_mask &= ~F_PL_INTR_EXT;
-	writel(adapter->slow_intr_mask | F_PL_INTR_SGE_DATA,
-		   adapter->regs + A_PL_ENABLE);
-	schedule_work(&adapter->ext_intr_handler_task);
-}
-
-void t1_fatal_err(struct adapter *adapter)
-{
-	if (adapter->flags & FULL_INIT_DONE) {
-		t1_sge_stop(adapter->sge);
-		t1_interrupts_disable(adapter);
-	}
-	pr_alert("%s: encountered fatal error, operation suspended\n",
-		 adapter->name);
-}
-
 static const struct net_device_ops cxgb_netdev_ops = {
 	.ndo_open		= cxgb_open,
 	.ndo_stop		= cxgb_close,
@@ -1062,8 +1018,6 @@ static int init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 			spin_lock_init(&adapter->async_lock);
 			spin_lock_init(&adapter->mac_lock);
 
-			INIT_WORK(&adapter->ext_intr_handler_task,
-				  ext_intr_task);
 			INIT_DELAYED_WORK(&adapter->stats_update_task,
 					  mac_stats_task);
 
diff --git a/drivers/net/ethernet/chelsio/cxgb/sge.c b/drivers/net/ethernet/chelsio/cxgb/sge.c
index 2d9c2b5a690a3..cda01f22c71c8 100644
--- a/drivers/net/ethernet/chelsio/cxgb/sge.c
+++ b/drivers/net/ethernet/chelsio/cxgb/sge.c
@@ -940,10 +940,11 @@ void t1_sge_intr_clear(struct sge *sge)
 /*
  * SGE 'Error' interrupt handler
  */
-int t1_sge_intr_error_handler(struct sge *sge)
+bool t1_sge_intr_error_handler(struct sge *sge)
 {
 	struct adapter *adapter = sge->adapter;
 	u32 cause = readl(adapter->regs + A_SG_INT_CAUSE);
+	bool wake = false;
 
 	if (adapter->port[0].dev->hw_features & NETIF_F_TSO)
 		cause &= ~F_PACKET_TOO_BIG;
@@ -967,11 +968,14 @@ int t1_sge_intr_error_handler(struct sge *sge)
 		sge->stats.pkt_mismatch++;
 		pr_alert("%s: SGE packet mismatch\n", adapter->name);
 	}
-	if (cause & SGE_INT_FATAL)
-		t1_fatal_err(adapter);
+	if (cause & SGE_INT_FATAL) {
+		t1_interrupts_disable(adapter);
+		adapter->pending_thread_intr |= F_PL_INTR_SGE_ERR;
+		wake = true;
+	}
 
 	writel(cause, adapter->regs + A_SG_INT_CAUSE);
-	return 0;
+	return wake;
 }
 
 const struct sge_intr_counts *t1_sge_get_intr_counts(const struct sge *sge)
@@ -1619,11 +1623,46 @@ int t1_poll(struct napi_struct *napi, int budget)
 	return work_done;
 }
 
+irqreturn_t t1_interrupt_thread(int irq, void *data)
+{
+	struct adapter *adapter = data;
+	u32 pending_thread_intr;
+
+	spin_lock_irq(&adapter->async_lock);
+	pending_thread_intr = adapter->pending_thread_intr;
+	adapter->pending_thread_intr = 0;
+	spin_unlock_irq(&adapter->async_lock);
+
+	if (!pending_thread_intr)
+		return IRQ_NONE;
+
+	if (pending_thread_intr & F_PL_INTR_EXT)
+		t1_elmer0_ext_intr_handler(adapter);
+
+	/* This error is fatal, interrupts remain off */
+	if (pending_thread_intr & F_PL_INTR_SGE_ERR) {
+		pr_alert("%s: encountered fatal error, operation suspended\n",
+			 adapter->name);
+		t1_sge_stop(adapter->sge);
+		return IRQ_HANDLED;
+	}
+
+	spin_lock_irq(&adapter->async_lock);
+	adapter->slow_intr_mask |= F_PL_INTR_EXT;
+
+	writel(F_PL_INTR_EXT, adapter->regs + A_PL_CAUSE);
+	writel(adapter->slow_intr_mask | F_PL_INTR_SGE_DATA,
+	       adapter->regs + A_PL_ENABLE);
+	spin_unlock_irq(&adapter->async_lock);
+
+	return IRQ_HANDLED;
+}
+
 irqreturn_t t1_interrupt(int irq, void *data)
 {
 	struct adapter *adapter = data;
 	struct sge *sge = adapter->sge;
-	int handled;
+	irqreturn_t handled;
 
 	if (likely(responses_pending(adapter))) {
 		writel(F_PL_INTR_SGE_DATA, adapter->regs + A_PL_CAUSE);
@@ -1645,10 +1684,10 @@ irqreturn_t t1_interrupt(int irq, void *data)
 	handled = t1_slow_intr_handler(adapter);
 	spin_unlock(&adapter->async_lock);
 
-	if (!handled)
+	if (handled == IRQ_NONE)
 		sge->stats.unhandled_irqs++;
 
-	return IRQ_RETVAL(handled != 0);
+	return handled;
 }
 
 /*
diff --git a/drivers/net/ethernet/chelsio/cxgb/sge.h b/drivers/net/ethernet/chelsio/cxgb/sge.h
index a1ba591b34312..716705b96f265 100644
--- a/drivers/net/ethernet/chelsio/cxgb/sge.h
+++ b/drivers/net/ethernet/chelsio/cxgb/sge.h
@@ -74,6 +74,7 @@ struct sge *t1_sge_create(struct adapter *, struct sge_params *);
 int t1_sge_configure(struct sge *, struct sge_params *);
 int t1_sge_set_coalesce_params(struct sge *, struct sge_params *);
 void t1_sge_destroy(struct sge *);
+irqreturn_t t1_interrupt_thread(int irq, void *data);
 irqreturn_t t1_interrupt(int irq, void *cookie);
 int t1_poll(struct napi_struct *, int);
 
@@ -81,7 +82,7 @@ netdev_tx_t t1_start_xmit(struct sk_buff *skb, struct net_device *dev);
 void t1_vlan_mode(struct adapter *adapter, netdev_features_t features);
 void t1_sge_start(struct sge *);
 void t1_sge_stop(struct sge *);
-int t1_sge_intr_error_handler(struct sge *);
+bool t1_sge_intr_error_handler(struct sge *sge);
 void t1_sge_intr_enable(struct sge *);
 void t1_sge_intr_disable(struct sge *);
 void t1_sge_intr_clear(struct sge *);
diff --git a/drivers/net/ethernet/chelsio/cxgb/subr.c b/drivers/net/ethernet/chelsio/cxgb/subr.c
index ea0f8741d7cfd..310add28fcf59 100644
--- a/drivers/net/ethernet/chelsio/cxgb/subr.c
+++ b/drivers/net/ethernet/chelsio/cxgb/subr.c
@@ -170,7 +170,7 @@ void t1_link_changed(adapter_t *adapter, int port_id)
 	t1_link_negotiated(adapter, port_id, link_ok, speed, duplex, fc);
 }
 
-static int t1_pci_intr_handler(adapter_t *adapter)
+static bool t1_pci_intr_handler(adapter_t *adapter)
 {
 	u32 pcix_cause;
 
@@ -179,9 +179,13 @@ static int t1_pci_intr_handler(adapter_t *adapter)
 	if (pcix_cause) {
 		pci_write_config_dword(adapter->pdev, A_PCICFG_INTR_CAUSE,
 				       pcix_cause);
-		t1_fatal_err(adapter);    /* PCI errors are fatal */
+		/* PCI errors are fatal */
+		t1_interrupts_disable(adapter);
+		adapter->pending_thread_intr |= F_PL_INTR_SGE_ERR;
+		pr_alert("%s: PCI error encountered.\n", adapter->name);
+		return true;
 	}
-	return 0;
+	return false;
 }
 
 #ifdef CONFIG_CHELSIO_T1_1G
@@ -210,13 +214,16 @@ static int fpga_phy_intr_handler(adapter_t *adapter)
 /*
  * Slow path interrupt handler for FPGAs.
  */
-static int fpga_slow_intr(adapter_t *adapter)
+static irqreturn_t fpga_slow_intr(adapter_t *adapter)
 {
 	u32 cause = readl(adapter->regs + A_PL_CAUSE);
+	irqreturn_t ret = IRQ_NONE;
 
 	cause &= ~F_PL_INTR_SGE_DATA;
-	if (cause & F_PL_INTR_SGE_ERR)
-		t1_sge_intr_error_handler(adapter->sge);
+	if (cause & F_PL_INTR_SGE_ERR) {
+		if (t1_sge_intr_error_handler(adapter->sge))
+			ret = IRQ_WAKE_THREAD;
+	}
 
 	if (cause & FPGA_PCIX_INTERRUPT_GMAC)
 		fpga_phy_intr_handler(adapter);
@@ -231,14 +238,19 @@ static int fpga_slow_intr(adapter_t *adapter)
 		/* Clear TP interrupt */
 		writel(tp_cause, adapter->regs + FPGA_TP_ADDR_INTERRUPT_CAUSE);
 	}
-	if (cause & FPGA_PCIX_INTERRUPT_PCIX)
-		t1_pci_intr_handler(adapter);
+	if (cause & FPGA_PCIX_INTERRUPT_PCIX) {
+		if (t1_pci_intr_handler(adapter))
+			ret = IRQ_WAKE_THREAD;
+	}
 
 	/* Clear the interrupts just processed. */
 	if (cause)
 		writel(cause, adapter->regs + A_PL_CAUSE);
 
-	return cause != 0;
+	if (ret != IRQ_NONE)
+		return ret;
+
+	return cause == 0 ? IRQ_NONE : IRQ_HANDLED;
 }
 #endif
 
@@ -842,31 +854,45 @@ void t1_interrupts_clear(adapter_t* adapter)
 /*
  * Slow path interrupt handler for ASICs.
  */
-static int asic_slow_intr(adapter_t *adapter)
+static irqreturn_t asic_slow_intr(adapter_t *adapter)
 {
 	u32 cause = readl(adapter->regs + A_PL_CAUSE);
+	irqreturn_t ret = IRQ_HANDLED;
 
 	cause &= adapter->slow_intr_mask;
 	if (!cause)
-		return 0;
-	if (cause & F_PL_INTR_SGE_ERR)
-		t1_sge_intr_error_handler(adapter->sge);
+		return IRQ_NONE;
+	if (cause & F_PL_INTR_SGE_ERR) {
+		if (t1_sge_intr_error_handler(adapter->sge))
+			ret = IRQ_WAKE_THREAD;
+	}
 	if (cause & F_PL_INTR_TP)
 		t1_tp_intr_handler(adapter->tp);
 	if (cause & F_PL_INTR_ESPI)
 		t1_espi_intr_handler(adapter->espi);
-	if (cause & F_PL_INTR_PCIX)
-		t1_pci_intr_handler(adapter);
-	if (cause & F_PL_INTR_EXT)
-		t1_elmer0_ext_intr(adapter);
+	if (cause & F_PL_INTR_PCIX) {
+		if (t1_pci_intr_handler(adapter))
+			ret = IRQ_WAKE_THREAD;
+	}
+	if (cause & F_PL_INTR_EXT) {
+		/* Wake the threaded interrupt to handle external interrupts as
+		 * we require a process context. We disable EXT interrupts in
+		 * the interim and let the thread reenable them when it's done.
+		 */
+		adapter->pending_thread_intr |= F_PL_INTR_EXT;
+		adapter->slow_intr_mask &= ~F_PL_INTR_EXT;
+		writel(adapter->slow_intr_mask | F_PL_INTR_SGE_DATA,
+		       adapter->regs + A_PL_ENABLE);
+		ret = IRQ_WAKE_THREAD;
+	}
 
 	/* Clear the interrupts just processed. */
 	writel(cause, adapter->regs + A_PL_CAUSE);
 	readl(adapter->regs + A_PL_CAUSE); /* flush writes */
-	return 1;
+	return ret;
 }
 
-int t1_slow_intr_handler(adapter_t *adapter)
+irqreturn_t t1_slow_intr_handler(adapter_t *adapter)
 {
 #ifdef CONFIG_CHELSIO_T1_1G
 	if (!t1_is_asic(adapter))

v5.10.14-rt28 fails to build without CONFIG_SMP

[Jonathan Schwender]

Hi Sebastian,

It seems that commit 17cfc9697f5574e4b523c21fca160aac5a3ac6dc "softirq: 
Update the WIP"
breaks builds without CONFIG_SMP, due to unresolved references to 
tasklet_unlock and tasklet_unlock_wait in softirq.c

In include/linux/interrupt.h the functions are declared if either 
CONFIG_SMP or CONFIG_PREEMPT_RT are defined.

However, in softirq.c the functions are now only in an #ifdef CONFIG_SMP 
block.


Regards

Jonathan Schwender

Re: v5.10.14-rt28 fails to build without CONFIG_SMP

[Sebastian Andrzej Siewior]

On 2021-02-14 11:54:27 [+0100], Jonathan Schwender wrote:
> Hi Sebastian,
Hi,

> It seems that commit 17cfc9697f5574e4b523c21fca160aac5a3ac6dc "softirq:
> Update the WIP"
> breaks builds without CONFIG_SMP, due to unresolved references to
> tasklet_unlock and tasklet_unlock_wait in softirq.c

Should not happen in v5.10.16-rt30.

> Regards
> 
> Jonathan Schwender

Sebastian