This is a note to let you know that I've just added the patch titled
sched: Unbreak wakeups
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sched-unbreak-wakeups.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 11b197bb78bb483ea0beda146466f859fb09f642
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Date: Fri Jun 11 10:28:11 2021 +0200
sched: Unbreak wakeups
[ Upstream commit 37aadc687ab441bbcb693ddae613acf9afcea1ab ]
Remove broken task->state references and let wake_up_process() DTRT.
The anti-pattern in these patches breaks the ordering of ->state vs
COND as described in the comment near set_current_state() and can lead
to missed wakeups:
(OoO load, observes RUNNING)<-.
for (;;) { |
t->state = UNINTERRUPTIBLE; |
smp_mb(); ,-----> | (observes !COND)
| /
if (COND) ---------' | COND = 1;
break; `- if (t->state != RUNNING)
wake_up_process(t); // not done
schedule(); // forever waiting
}
t->state = TASK_RUNNING;
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Reviewed-by: Davidlohr Bueso <dbueso@xxxxxxx>
Acked-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Acked-by: Will Deacon <will@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210611082838.160855222@xxxxxxxxxxxxx
Stable-dep-of: 2d7198278ece ("qca_spi: Make interrupt remembering atomic")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/net/ethernet/qualcomm/qca_spi.c b/drivers/net/ethernet/qualcomm/qca_spi.c
index ffa1846f5b4c4..336e5d185f5fe 100644
--- a/drivers/net/ethernet/qualcomm/qca_spi.c
+++ b/drivers/net/ethernet/qualcomm/qca_spi.c
@@ -670,8 +670,7 @@ qcaspi_intr_handler(int irq, void *data)
struct qcaspi *qca = data;
qca->intr_req++;
- if (qca->spi_thread &&
- qca->spi_thread->state != TASK_RUNNING)
+ if (qca->spi_thread)
wake_up_process(qca->spi_thread);
return IRQ_HANDLED;
@@ -794,8 +793,7 @@ qcaspi_netdev_xmit(struct sk_buff *skb, struct net_device *dev)
netif_trans_update(dev);
- if (qca->spi_thread &&
- qca->spi_thread->state != TASK_RUNNING)
+ if (qca->spi_thread)
wake_up_process(qca->spi_thread);
return NETDEV_TX_OK;
diff --git a/drivers/usb/gadget/udc/max3420_udc.c b/drivers/usb/gadget/udc/max3420_udc.c
index 91c9e9057cff3..d2a2b20cc1ad4 100644
--- a/drivers/usb/gadget/udc/max3420_udc.c
+++ b/drivers/usb/gadget/udc/max3420_udc.c
@@ -509,8 +509,7 @@ static irqreturn_t max3420_vbus_handler(int irq, void *dev_id)
? USB_STATE_POWERED : USB_STATE_NOTATTACHED);
spin_unlock_irqrestore(&udc->lock, flags);
- if (udc->thread_task &&
- udc->thread_task->state != TASK_RUNNING)
+ if (udc->thread_task)
wake_up_process(udc->thread_task);
return IRQ_HANDLED;
@@ -529,8 +528,7 @@ static irqreturn_t max3420_irq_handler(int irq, void *dev_id)
}
spin_unlock_irqrestore(&udc->lock, flags);
- if (udc->thread_task &&
- udc->thread_task->state != TASK_RUNNING)
+ if (udc->thread_task)
wake_up_process(udc->thread_task);
return IRQ_HANDLED;
@@ -1093,8 +1091,7 @@ static int max3420_wakeup(struct usb_gadget *gadget)
spin_unlock_irqrestore(&udc->lock, flags);
- if (udc->thread_task &&
- udc->thread_task->state != TASK_RUNNING)
+ if (udc->thread_task)
wake_up_process(udc->thread_task);
return ret;
}
@@ -1117,8 +1114,7 @@ static int max3420_udc_start(struct usb_gadget *gadget,
udc->todo |= UDC_START;
spin_unlock_irqrestore(&udc->lock, flags);
- if (udc->thread_task &&
- udc->thread_task->state != TASK_RUNNING)
+ if (udc->thread_task)
wake_up_process(udc->thread_task);
return 0;
@@ -1137,8 +1133,7 @@ static int max3420_udc_stop(struct usb_gadget *gadget)
udc->todo |= UDC_START;
spin_unlock_irqrestore(&udc->lock, flags);
- if (udc->thread_task &&
- udc->thread_task->state != TASK_RUNNING)
+ if (udc->thread_task)
wake_up_process(udc->thread_task);
return 0;
diff --git a/drivers/usb/host/max3421-hcd.c b/drivers/usb/host/max3421-hcd.c
index b875da01c5309..21b1e5e1958a6 100644
--- a/drivers/usb/host/max3421-hcd.c
+++ b/drivers/usb/host/max3421-hcd.c
@@ -1139,8 +1139,7 @@ max3421_irq_handler(int irq, void *dev_id)
struct spi_device *spi = to_spi_device(hcd->self.controller);
struct max3421_hcd *max3421_hcd = hcd_to_max3421(hcd);
- if (max3421_hcd->spi_thread &&
- max3421_hcd->spi_thread->state != TASK_RUNNING)
+ if (max3421_hcd->spi_thread)
wake_up_process(max3421_hcd->spi_thread);
if (!test_and_set_bit(ENABLE_IRQ, &max3421_hcd->todo))
disable_irq_nosync(spi->irq);
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 09229ad822096..ded3dc45680bd 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -72,7 +72,7 @@ static void wakeup_softirqd(void)
/* Interrupts are disabled: no need to stop preemption */
struct task_struct *tsk = __this_cpu_read(ksoftirqd);
- if (tsk && tsk->state != TASK_RUNNING)
+ if (tsk)
wake_up_process(tsk);
}
