[ANNOUNCE] v5.11-rt5

From: Sebastian Andrzej Siewior
Date: Tue Feb 16 2021 - 12:13:35 EST

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Dear RT folks!

I'm pleased to announce the v5.11-rt5 patch set.

Changes since v5.11-rt4:

- 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.

- Due to recent softirq rework it was not possible to compile a kernel
with RT && !SMP. Reported by Jonathan Schwender, patch by Christian
Eggers.

- Update the block-mq patches to the version, that has been staged for
upstream.

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 v5.11-rt4 is appended below and can be found here:

https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.11/incr/patch-5.11-rt4-rt5.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 v5.11-rt5

The RT patch against v5.11 can be found here:

https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.11/older/patch-5.11-rt5.patch.xz

The split quilt queue is available at:

https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.11/older/patches-5.11-rt5.tar.xz

Sebastian

diff --git a/arch/powerpc/kernel/syscall_64.c b/arch/powerpc/kernel/syscall_64.c
index b304c68dbcf50..092c014b0653e 100644
--- a/arch/powerpc/kernel/syscall_64.c
+++ b/arch/powerpc/kernel/syscall_64.c
@@ -401,7 +401,8 @@ 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))
diff --git a/kernel/smp.c b/kernel/smp.c
index 1b6070bf97bb0..01e9d01d1866e 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -14,6 +14,7 @@
#include <linux/export.h>
#include <linux/percpu.h>
#include <linux/init.h>
+#include <linux/interrupt.h>
#include <linux/gfp.h>
#include <linux/smp.h>
#include <linux/cpu.h>
@@ -449,6 +450,19 @@ void flush_smp_call_function_from_idle(void)

local_irq_save(flags);
flush_smp_call_function_queue(true);
+
+ if (local_softirq_pending()) {
+
+ if (!IS_ENABLED(CONFIG_PREEMPT_RT)) {
+ do_softirq();
+ } else {
+ struct task_struct *ksoftirqd = this_cpu_ksoftirqd();
+
+ if (ksoftirqd && ksoftirqd->state != TASK_RUNNING)
+ wake_up_process(ksoftirqd);
+ }
+ }
+
local_irq_restore(flags);
}

diff --git a/kernel/softirq.c b/kernel/softirq.c
index 8f4c141b20c05..a9b66aa086366 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -867,7 +867,7 @@ void tasklet_kill(struct tasklet_struct *t)
}
EXPORT_SYMBOL(tasklet_kill);

-#ifdef CONFIG_SMP
+#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RT)
void tasklet_unlock(struct tasklet_struct *t)
{
smp_mb__before_atomic();
diff --git a/localversion-rt b/localversion-rt
index ad3da1bcab7e8..0efe7ba1930e1 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt4
+-rt5

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