[RFC PATCH 2/3] chelsio: cxgb: Move slow interrupt handling to threaded irqs

Ahmed S. Darwish
2020-12-24T13:12:52Z

The t1_interrupt() irq handler calls del_timer_sync() down the chain:

sge.c: t1_interrupt()
-> subr.c: t1_slow_intr_handler()
-> asic_slow_intr() || fpga_slow_intr()
-> t1_pci_intr_handler()
-> cxgb2.c: t1_fatal_err() # Cont. at [*]
-> fpga_slow_intr()
-> sge.c: t1_sge_intr_error_handler()
-> cxgb2.c: t1_fatal_err() # Cont. at [*]

[*] cxgb2.c: t1_fatal_err()
-> sge.c: t1_sge_stop()
-> timer.c: del_timer_sync()

This is invalid: if an irq handler calls del_timer_sync() on a timer it
has already interrupted, it will loop forever.

Move the slow t1 interrupt handling path, t1_slow_intr_handler(), to a
threaded-irq task context.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
---
drivers/net/ethernet/chelsio/cxgb/cxgb2.c | 6 +++---
drivers/net/ethernet/chelsio/cxgb/sge.c | 13 +++++++++++--
drivers/net/ethernet/chelsio/cxgb/sge.h | 3 ++-
3 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/chelsio/cxgb/cxgb2.c b/drivers/net/ethernet/chelsio/cxgb/cxgb2.c
index 7b5a98330ef7..c96bdca4f270 100644
--- a/drivers/net/ethernet/chelsio/cxgb/cxgb2.c
+++ b/drivers/net/ethernet/chelsio/cxgb/cxgb2.c
@@ -211,9 +211,9 @@ 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_irq, t1_irq_thread,
+ adapter->params.has_msi ? 0 : IRQF_SHARED,
+ adapter->name, adapter);
if (err) {
if (adapter->params.has_msi)
pci_disable_msi(adapter->pdev);
diff --git a/drivers/net/ethernet/chelsio/cxgb/sge.c b/drivers/net/ethernet/chelsio/cxgb/sge.c
index d6df1a87db0b..f1c402f6b889 100644
--- a/drivers/net/ethernet/chelsio/cxgb/sge.c
+++ b/drivers/net/ethernet/chelsio/cxgb/sge.c
@@ -1626,11 +1626,10 @@ int t1_poll(struct napi_struct *napi, int budget)
return work_done;
}

-irqreturn_t t1_interrupt(int irq, void *data)
+irqreturn_t t1_irq(int irq, void *data)
{
struct adapter *adapter = data;
struct sge *sge = adapter->sge;
- int handled;

if (likely(responses_pending(adapter))) {
writel(F_PL_INTR_SGE_DATA, adapter->regs + A_PL_CAUSE);
@@ -1645,9 +1644,19 @@ irqreturn_t t1_interrupt(int irq, void *data)
napi_enable(&adapter->napi);
}
}
+
return IRQ_HANDLED;
}

+ return IRQ_WAKE_THREAD;
+}
+
+irqreturn_t t1_irq_thread(int irq, void *data)
+{
+ struct adapter *adapter = data;
+ struct sge *sge = adapter->sge;
+ int handled;
+
spin_lock(&adapter->async_lock);
handled = t1_slow_intr_handler(adapter);
spin_unlock(&adapter->async_lock);
diff --git a/drivers/net/ethernet/chelsio/cxgb/sge.h b/drivers/net/ethernet/chelsio/cxgb/sge.h
index a1ba591b3431..4072b3fb312b 100644
--- a/drivers/net/ethernet/chelsio/cxgb/sge.h
+++ b/drivers/net/ethernet/chelsio/cxgb/sge.h
@@ -74,7 +74,8 @@ 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(int irq, void *cookie);
+irqreturn_t t1_irq(int irq, void *cookie);
+irqreturn_t t1_irq_thread(int irq, void *cookie);
int t1_poll(struct napi_struct *, int);

netdev_tx_t t1_start_xmit(struct sk_buff *skb, struct net_device *dev);
--
2.29.2