The SDMA engine used by TEMAC halts operation when it has finished
processing of the last buffer descriptor in the buffer ring.
Unfortunately, no interrupt event is generated when this happens,
so we need to setup another mechanism to make sure DMA operation is
restarted when enough buffers have been added to the ring.
Signed-off-by: Esben Haabendal <esben(a)geanix.com>
Cc: stable(a)vger.kernel.org
---
drivers/net/ethernet/xilinx/ll_temac.h | 3 ++
drivers/net/ethernet/xilinx/ll_temac_main.c | 47 ++++++++++++++++++++-
2 files changed, 48 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/xilinx/ll_temac.h b/drivers/net/ethernet/xilinx/ll_temac.h
index 99fe059e5c7f..53fb8141f1a6 100644
--- a/drivers/net/ethernet/xilinx/ll_temac.h
+++ b/drivers/net/ethernet/xilinx/ll_temac.h
@@ -380,6 +380,9 @@ struct temac_local {
/* DMA channel control setup */
u32 tx_chnl_ctrl;
u32 rx_chnl_ctrl;
+ u8 coalesce_count_rx;
+
+ struct delayed_work restart_work;
};
/* Wrappers for temac_ior()/temac_iow() function pointers above */
diff --git a/drivers/net/ethernet/xilinx/ll_temac_main.c b/drivers/net/ethernet/xilinx/ll_temac_main.c
index 255207f2fd27..90b486becb5b 100644
--- a/drivers/net/ethernet/xilinx/ll_temac_main.c
+++ b/drivers/net/ethernet/xilinx/ll_temac_main.c
@@ -51,6 +51,7 @@
#include <linux/ip.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
+#include <linux/workqueue.h>
#include <linux/dma-mapping.h>
#include <linux/processor.h>
#include <linux/platform_data/xilinx-ll-temac.h>
@@ -920,6 +921,17 @@ temac_start_xmit(struct sk_buff *skb, struct net_device *ndev)
return NETDEV_TX_OK;
}
+static int ll_temac_recv_buffers_available(struct temac_local *lp)
+{
+ int available;
+
+ if (!lp->rx_skb[lp->rx_bd_ci])
+ return 0;
+ available = 1 + lp->rx_bd_tail - lp->rx_bd_ci;
+ if (available <= 0)
+ available += RX_BD_NUM;
+ return available;
+}
static void ll_temac_recv(struct net_device *ndev)
{
@@ -990,6 +1002,18 @@ static void ll_temac_recv(struct net_device *ndev)
lp->rx_bd_ci = 0;
} while (rx_bd != lp->rx_bd_tail);
+ /* DMA operations will halt when the last buffer descriptor is
+ * processed (ie. the one pointed to by RX_TAILDESC_PTR).
+ * When that happens, no more interrupt events will be
+ * generated. No IRQ_COAL or IRQ_DLY, and not even an
+ * IRQ_ERR. To avoid stalling, we schedule a delayed work
+ * when there is a potential risk of that happening. The work
+ * will call this function, and thus re-schedule itself until
+ * enough buffers are available again.
+ */
+ if (ll_temac_recv_buffers_available(lp) < lp->coalesce_count_rx)
+ schedule_delayed_work(&lp->restart_work, HZ / 1000);
+
/* Allocate new buffers for those buffer descriptors that were
* passed to network stack. Note that GFP_ATOMIC allocations
* can fail (e.g. when a larger burst of GFP_ATOMIC
@@ -1045,6 +1069,18 @@ static void ll_temac_recv(struct net_device *ndev)
spin_unlock_irqrestore(&lp->rx_lock, flags);
}
+/* Function scheduled to ensure a restart in case of DMA halt
+ * condition caused by running out of buffer descriptors.
+ */
+static void ll_temac_restart_work_func(struct work_struct *work)
+{
+ struct temac_local *lp = container_of(work, struct temac_local,
+ restart_work.work);
+ struct net_device *ndev = lp->ndev;
+
+ ll_temac_recv(ndev);
+}
+
static irqreturn_t ll_temac_tx_irq(int irq, void *_ndev)
{
struct net_device *ndev = _ndev;
@@ -1137,6 +1173,8 @@ static int temac_stop(struct net_device *ndev)
dev_dbg(&ndev->dev, "temac_close()\n");
+ cancel_delayed_work_sync(&lp->restart_work);
+
free_irq(lp->tx_irq, ndev);
free_irq(lp->rx_irq, ndev);
@@ -1258,6 +1296,7 @@ static int temac_probe(struct platform_device *pdev)
lp->dev = &pdev->dev;
lp->options = XTE_OPTION_DEFAULTS;
spin_lock_init(&lp->rx_lock);
+ INIT_DELAYED_WORK(&lp->restart_work, ll_temac_restart_work_func);
/* Setup mutex for synchronization of indirect register access */
if (pdata) {
@@ -1364,6 +1403,7 @@ static int temac_probe(struct platform_device *pdev)
*/
lp->tx_chnl_ctrl = 0x10220000;
lp->rx_chnl_ctrl = 0xff070000;
+ lp->coalesce_count_rx = 0x07;
/* Finished with the DMA node; drop the reference */
of_node_put(dma_np);
@@ -1395,11 +1435,14 @@ static int temac_probe(struct platform_device *pdev)
(pdata->tx_irq_count << 16);
else
lp->tx_chnl_ctrl = 0x10220000;
- if (pdata->rx_irq_timeout || pdata->rx_irq_count)
+ if (pdata->rx_irq_timeout || pdata->rx_irq_count) {
lp->rx_chnl_ctrl = (pdata->rx_irq_timeout << 24) |
(pdata->rx_irq_count << 16);
- else
+ lp->coalesce_count_rx = pdata->rx_irq_count;
+ } else {
lp->rx_chnl_ctrl = 0xff070000;
+ lp->coalesce_count_rx = 0x07;
+ }
}
/* Error handle returned DMA RX and TX interrupts */
--
2.25.0
It is possible that the interrupt handler fires and frees up space in
the TX ring in between checking for sufficient TX ring space and
stopping the TX queue in temac_start_xmit. If this happens, the
queue wake from the interrupt handler will occur before the queue is
stopped, causing a lost wakeup and the adapter's transmit hanging.
To avoid this, after stopping the queue, check again whether there is
sufficient space in the TX ring. If so, wake up the queue again.
This is a port of the similar fix in axienet driver,
commit 7de44285c1f6 ("net: axienet: Fix race condition causing TX hang").
Signed-off-by: Esben Haabendal <esben(a)geanix.com>
Cc: stable(a)vger.kernel.org
---
drivers/net/ethernet/xilinx/ll_temac_main.c | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)
diff --git a/drivers/net/ethernet/xilinx/ll_temac_main.c b/drivers/net/ethernet/xilinx/ll_temac_main.c
index 6f11f52c9a9e..996004ef8bd4 100644
--- a/drivers/net/ethernet/xilinx/ll_temac_main.c
+++ b/drivers/net/ethernet/xilinx/ll_temac_main.c
@@ -788,6 +788,9 @@ static void temac_start_xmit_done(struct net_device *ndev)
stat = be32_to_cpu(cur_p->app0);
}
+ /* Matches barrier in temac_start_xmit */
+ smp_mb();
+
netif_wake_queue(ndev);
}
@@ -830,9 +833,19 @@ temac_start_xmit(struct sk_buff *skb, struct net_device *ndev)
cur_p = &lp->tx_bd_v[lp->tx_bd_tail];
if (temac_check_tx_bd_space(lp, num_frag + 1)) {
- if (!netif_queue_stopped(ndev))
- netif_stop_queue(ndev);
- return NETDEV_TX_BUSY;
+ if (netif_queue_stopped(ndev))
+ return NETDEV_TX_BUSY;
+
+ netif_stop_queue(ndev);
+
+ /* Matches barrier in temac_start_xmit_done */
+ smp_mb();
+
+ /* Space might have just been freed - check again */
+ if (temac_check_tx_bd_space(lp, num_frag))
+ return NETDEV_TX_BUSY;
+
+ netif_wake_queue(ndev);
}
cur_p->app0 = 0;
--
2.25.0
The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 684c0422da71da0cd81319c90b8099b563b13da4 Mon Sep 17 00:00:00 2001
From: Oliver Upton <oupton(a)google.com>
Date: Fri, 7 Feb 2020 02:36:05 -0800
Subject: [PATCH] KVM: nVMX: Handle pending #DB when injecting INIT VM-exit
SDM 27.3.4 states that the 'pending debug exceptions' VMCS field will
be populated if a VM-exit caused by an INIT signal takes priority over a
debug-trap. Emulate this behavior when synthesizing an INIT signal
VM-exit into L1.
Fixes: 4b9852f4f389 ("KVM: x86: Fix INIT signal handling in various CPU states")
Signed-off-by: Oliver Upton <oupton(a)google.com>
Signed-off-by: Paolo Bonzini <pbonzini(a)redhat.com>
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 657c2eda357c..1586aaae3a6f 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -3575,6 +3575,33 @@ static void nested_vmx_inject_exception_vmexit(struct kvm_vcpu *vcpu,
nested_vmx_vmexit(vcpu, EXIT_REASON_EXCEPTION_NMI, intr_info, exit_qual);
}
+/*
+ * Returns true if a debug trap is pending delivery.
+ *
+ * In KVM, debug traps bear an exception payload. As such, the class of a #DB
+ * exception may be inferred from the presence of an exception payload.
+ */
+static inline bool vmx_pending_dbg_trap(struct kvm_vcpu *vcpu)
+{
+ return vcpu->arch.exception.pending &&
+ vcpu->arch.exception.nr == DB_VECTOR &&
+ vcpu->arch.exception.payload;
+}
+
+/*
+ * Certain VM-exits set the 'pending debug exceptions' field to indicate a
+ * recognized #DB (data or single-step) that has yet to be delivered. Since KVM
+ * represents these debug traps with a payload that is said to be compatible
+ * with the 'pending debug exceptions' field, write the payload to the VMCS
+ * field if a VM-exit is delivered before the debug trap.
+ */
+static void nested_vmx_update_pending_dbg(struct kvm_vcpu *vcpu)
+{
+ if (vmx_pending_dbg_trap(vcpu))
+ vmcs_writel(GUEST_PENDING_DBG_EXCEPTIONS,
+ vcpu->arch.exception.payload);
+}
+
static int vmx_check_nested_events(struct kvm_vcpu *vcpu, bool external_intr)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -3587,6 +3614,7 @@ static int vmx_check_nested_events(struct kvm_vcpu *vcpu, bool external_intr)
test_bit(KVM_APIC_INIT, &apic->pending_events)) {
if (block_nested_events)
return -EBUSY;
+ nested_vmx_update_pending_dbg(vcpu);
clear_bit(KVM_APIC_INIT, &apic->pending_events);
nested_vmx_vmexit(vcpu, EXIT_REASON_INIT_SIGNAL, 0, 0);
return 0;
The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 8ac0e6641c7ca14833a2a8c6f13d8e0a435e535c Mon Sep 17 00:00:00 2001
From: Zhu Yanjun <yanjunz(a)mellanox.com>
Date: Wed, 12 Feb 2020 09:26:33 +0200
Subject: [PATCH] RDMA/rxe: Fix soft lockup problem due to using tasklets in
softirq
When run stress tests with RXE, the following Call Traces often occur
watchdog: BUG: soft lockup - CPU#2 stuck for 22s! [swapper/2:0]
...
Call Trace:
<IRQ>
create_object+0x3f/0x3b0
kmem_cache_alloc_node_trace+0x129/0x2d0
__kmalloc_reserve.isra.52+0x2e/0x80
__alloc_skb+0x83/0x270
rxe_init_packet+0x99/0x150 [rdma_rxe]
rxe_requester+0x34e/0x11a0 [rdma_rxe]
rxe_do_task+0x85/0xf0 [rdma_rxe]
tasklet_action_common.isra.21+0xeb/0x100
__do_softirq+0xd0/0x298
irq_exit+0xc5/0xd0
smp_apic_timer_interrupt+0x68/0x120
apic_timer_interrupt+0xf/0x20
</IRQ>
...
The root cause is that tasklet is actually a softirq. In a tasklet
handler, another softirq handler is triggered. Usually these softirq
handlers run on the same cpu core. So this will cause "soft lockup Bug".
Fixes: 8700e3e7c485 ("Soft RoCE driver")
Link: https://lore.kernel.org/r/20200212072635.682689-8-leon@kernel.org
Signed-off-by: Zhu Yanjun <yanjunz(a)mellanox.com>
Signed-off-by: Leon Romanovsky <leonro(a)mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg(a)mellanox.com>
diff --git a/drivers/infiniband/sw/rxe/rxe_comp.c b/drivers/infiniband/sw/rxe/rxe_comp.c
index 116cafc9afcf..4bc88708b355 100644
--- a/drivers/infiniband/sw/rxe/rxe_comp.c
+++ b/drivers/infiniband/sw/rxe/rxe_comp.c
@@ -329,7 +329,7 @@ static inline enum comp_state check_ack(struct rxe_qp *qp,
qp->comp.psn = pkt->psn;
if (qp->req.wait_psn) {
qp->req.wait_psn = 0;
- rxe_run_task(&qp->req.task, 1);
+ rxe_run_task(&qp->req.task, 0);
}
}
return COMPST_ERROR_RETRY;
@@ -463,7 +463,7 @@ static void do_complete(struct rxe_qp *qp, struct rxe_send_wqe *wqe)
*/
if (qp->req.wait_fence) {
qp->req.wait_fence = 0;
- rxe_run_task(&qp->req.task, 1);
+ rxe_run_task(&qp->req.task, 0);
}
}
@@ -479,7 +479,7 @@ static inline enum comp_state complete_ack(struct rxe_qp *qp,
if (qp->req.need_rd_atomic) {
qp->comp.timeout_retry = 0;
qp->req.need_rd_atomic = 0;
- rxe_run_task(&qp->req.task, 1);
+ rxe_run_task(&qp->req.task, 0);
}
}
@@ -725,7 +725,7 @@ int rxe_completer(void *arg)
RXE_CNT_COMP_RETRY);
qp->req.need_retry = 1;
qp->comp.started_retry = 1;
- rxe_run_task(&qp->req.task, 1);
+ rxe_run_task(&qp->req.task, 0);
}
if (pkt) {
The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 8ac0e6641c7ca14833a2a8c6f13d8e0a435e535c Mon Sep 17 00:00:00 2001
From: Zhu Yanjun <yanjunz(a)mellanox.com>
Date: Wed, 12 Feb 2020 09:26:33 +0200
Subject: [PATCH] RDMA/rxe: Fix soft lockup problem due to using tasklets in
softirq
When run stress tests with RXE, the following Call Traces often occur
watchdog: BUG: soft lockup - CPU#2 stuck for 22s! [swapper/2:0]
...
Call Trace:
<IRQ>
create_object+0x3f/0x3b0
kmem_cache_alloc_node_trace+0x129/0x2d0
__kmalloc_reserve.isra.52+0x2e/0x80
__alloc_skb+0x83/0x270
rxe_init_packet+0x99/0x150 [rdma_rxe]
rxe_requester+0x34e/0x11a0 [rdma_rxe]
rxe_do_task+0x85/0xf0 [rdma_rxe]
tasklet_action_common.isra.21+0xeb/0x100
__do_softirq+0xd0/0x298
irq_exit+0xc5/0xd0
smp_apic_timer_interrupt+0x68/0x120
apic_timer_interrupt+0xf/0x20
</IRQ>
...
The root cause is that tasklet is actually a softirq. In a tasklet
handler, another softirq handler is triggered. Usually these softirq
handlers run on the same cpu core. So this will cause "soft lockup Bug".
Fixes: 8700e3e7c485 ("Soft RoCE driver")
Link: https://lore.kernel.org/r/20200212072635.682689-8-leon@kernel.org
Signed-off-by: Zhu Yanjun <yanjunz(a)mellanox.com>
Signed-off-by: Leon Romanovsky <leonro(a)mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg(a)mellanox.com>
diff --git a/drivers/infiniband/sw/rxe/rxe_comp.c b/drivers/infiniband/sw/rxe/rxe_comp.c
index 116cafc9afcf..4bc88708b355 100644
--- a/drivers/infiniband/sw/rxe/rxe_comp.c
+++ b/drivers/infiniband/sw/rxe/rxe_comp.c
@@ -329,7 +329,7 @@ static inline enum comp_state check_ack(struct rxe_qp *qp,
qp->comp.psn = pkt->psn;
if (qp->req.wait_psn) {
qp->req.wait_psn = 0;
- rxe_run_task(&qp->req.task, 1);
+ rxe_run_task(&qp->req.task, 0);
}
}
return COMPST_ERROR_RETRY;
@@ -463,7 +463,7 @@ static void do_complete(struct rxe_qp *qp, struct rxe_send_wqe *wqe)
*/
if (qp->req.wait_fence) {
qp->req.wait_fence = 0;
- rxe_run_task(&qp->req.task, 1);
+ rxe_run_task(&qp->req.task, 0);
}
}
@@ -479,7 +479,7 @@ static inline enum comp_state complete_ack(struct rxe_qp *qp,
if (qp->req.need_rd_atomic) {
qp->comp.timeout_retry = 0;
qp->req.need_rd_atomic = 0;
- rxe_run_task(&qp->req.task, 1);
+ rxe_run_task(&qp->req.task, 0);
}
}
@@ -725,7 +725,7 @@ int rxe_completer(void *arg)
RXE_CNT_COMP_RETRY);
qp->req.need_retry = 1;
qp->comp.started_retry = 1;
- rxe_run_task(&qp->req.task, 1);
+ rxe_run_task(&qp->req.task, 0);
}
if (pkt) {