2014-11-30 11:57:09

by Lino Sanfilippo

Subject: [PATCH] sky2: avoid pci write posting after disabling irqs

In sky2_change_mtu setting B0_IMSK to 0 may be delayed due to PCI write posting
which could result in irqs being still active when synchronize_irq is called.
Since we are not prepared to handle any further irqs after synchronize_irq
(our resources are freed after that) force the write by a consecutive read from
the same register.
Similar situation in sky2_all_down: Here we disabled irqs by a write to B0_IMSK
but did not ensure that this write took place before synchronize_irq. Fix that
too.

Signed-off-by: Lino Sanfilippo <[email protected]>
---
drivers/net/ethernet/marvell/sky2.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/marvell/sky2.c b/drivers/net/ethernet/marvell/sky2.c
index bd33662..f14544c 100644
--- a/drivers/net/ethernet/marvell/sky2.c
+++ b/drivers/net/ethernet/marvell/sky2.c
@@ -2419,6 +2419,7 @@ static int sky2_change_mtu(struct net_device *dev, int new_mtu)

imask = sky2_read32(hw, B0_IMSK);
sky2_write32(hw, B0_IMSK, 0);
+ sky2_read32(hw, B0_IMSK);

dev->trans_start = jiffies; /* prevent tx timeout */
napi_disable(&hw->napi);
@@ -3487,8 +3488,8 @@ static void sky2_all_down(struct sky2_hw *hw)
int i;

if (hw->flags & SKY2_HW_IRQ_SETUP) {
- sky2_read32(hw, B0_IMSK);
sky2_write32(hw, B0_IMSK, 0);
+ sky2_read32(hw, B0_IMSK);

synchronize_irq(hw->pdev->irq);
napi_disable(&hw->napi);
--
1.9.1

2014-11-30 17:54:36

by Stephen Hemminger

Subject: Re: [PATCH] sky2: avoid pci write posting after disabling irqs

On Sun, 30 Nov 2014 12:56:51 +0100
Lino Sanfilippo <[email protected]> wrote:

> In sky2_change_mtu setting B0_IMSK to 0 may be delayed due to PCI write posting
> which could result in irqs being still active when synchronize_irq is called.
> Since we are not prepared to handle any further irqs after synchronize_irq
> (our resources are freed after that) force the write by a consecutive read from
> the same register.
> Similar situation in sky2_all_down: Here we disabled irqs by a write to B0_IMSK
> but did not ensure that this write took place before synchronize_irq. Fix that
> too.
>
> Signed-off-by: Lino Sanfilippo <[email protected]>

Looks correct.

Acked-by: Stephen Hemminger <[email protected]>

2014-12-06 05:29:57

by David Miller

Subject: Re: [PATCH] sky2: avoid pci write posting after disabling irqs

From: Lino Sanfilippo <[email protected]>
Date: Sun, 30 Nov 2014 12:56:51 +0100

> In sky2_change_mtu setting B0_IMSK to 0 may be delayed due to PCI write posting
> which could result in irqs being still active when synchronize_irq is called.
> Since we are not prepared to handle any further irqs after synchronize_irq
> (our resources are freed after that) force the write by a consecutive read from
> the same register.
> Similar situation in sky2_all_down: Here we disabled irqs by a write to B0_IMSK
> but did not ensure that this write took place before synchronize_irq. Fix that
> too.
>
> Signed-off-by: Lino Sanfilippo <[email protected]>

Applied.