Re: [RFC 13/13] scsi: megaraid: Make use of dev_64bit_mmio_supported()
On Fri, Feb 26, 2021 at 3:30 PM Arnd Bergmann wrote:
>
> On Fri, Feb 26, 2021 at 3:03 PM Nicolas Saenz Julienne
> wrote:
>
> > unsigned long flags;
> > - spin_lock_irqsave(>hba_lock, flags);
> > - writel(le32_to_cpu(req_desc->u.low),
> > - >reg_set->inbound_low_queue_port);
> > - writel(le32_to_cpu(req_desc->u.high),
> > - >reg_set->inbound_high_queue_port);
> > - spin_unlock_irqrestore(>hba_lock, flags);
>
> > +
> > + if (dev_64bit_mmio_supported(>pdev->dev)) {
> > + writeq(req_data,
> > >reg_set->inbound_low_queue_port);
> > + } else {
> > + spin_lock_irqsave(>hba_lock, flags);
> > + lo_hi_writeq(req_data,
> > >reg_set->inbound_low_queue_port);
> > + spin_unlock_irqrestore(>hba_lock, flags);
> > + }
>
> I see your patch changes the code to the lo_hi_writeq() accessor,
> and it also fixes the endianness bug (double byteswap on big-endian),
> but it does not fix the spinlock bug (writel on pci leaks out of the lock
> unless it's followed by a read).
On second look, it seems your patch breaks the byteorder logic,
rather than fixing it. It would seem better to leave it unchanged
then, or to send a separate rework of the endianness conversion if
you think it is wrong.
Arnd
Re: [RFC 13/13] scsi: megaraid: Make use of dev_64bit_mmio_supported()
On Fri, Feb 26, 2021 at 3:03 PM Nicolas Saenz Julienne
wrote:
> unsigned long flags;
> - spin_lock_irqsave(>hba_lock, flags);
> - writel(le32_to_cpu(req_desc->u.low),
> - >reg_set->inbound_low_queue_port);
> - writel(le32_to_cpu(req_desc->u.high),
> - >reg_set->inbound_high_queue_port);
> - spin_unlock_irqrestore(>hba_lock, flags);
> +
> + if (dev_64bit_mmio_supported(>pdev->dev)) {
> + writeq(req_data, >reg_set->inbound_low_queue_port);
> + } else {
> + spin_lock_irqsave(>hba_lock, flags);
> + lo_hi_writeq(req_data,
> >reg_set->inbound_low_queue_port);
> + spin_unlock_irqrestore(>hba_lock, flags);
> + }
I see your patch changes the code to the lo_hi_writeq() accessor,
and it also fixes the endianness bug (double byteswap on big-endian),
but it does not fix the spinlock bug (writel on pci leaks out of the lock
unless it's followed by a read).
I'd suggest splitting the bugfix from the cleanup here, and fixing both
of the bugs while you're at it.
Arnd
[RFC 13/13] scsi: megaraid: Make use of dev_64bit_mmio_supported()
Instead of relying on defines use dev_64bit_mmio_supported(), which
provides the same functionality. On top of that convert the
implementation to lo_hi_writeq(), for a cleaner end result.
Signed-off-by: Nicolas Saenz Julienne
---
drivers/scsi/megaraid/megaraid_sas_fusion.c | 23 ++---
1 file changed, 11 insertions(+), 12 deletions(-)
diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c
b/drivers/scsi/megaraid/megaraid_sas_fusion.c
index 38fc9467c625..d4933a591330 100644
--- a/drivers/scsi/megaraid/megaraid_sas_fusion.c
+++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c
@@ -36,6 +36,7 @@
#include
#include
#include
+#include
#include
#include
@@ -259,19 +260,17 @@ static void
megasas_write_64bit_req_desc(struct megasas_instance *instance,
union MEGASAS_REQUEST_DESCRIPTOR_UNION *req_desc)
{
-#if defined(writeq) && defined(CONFIG_64BIT)
- u64 req_data = (((u64)le32_to_cpu(req_desc->u.high) << 32) |
- le32_to_cpu(req_desc->u.low));
- writeq(req_data, >reg_set->inbound_low_queue_port);
-#else
+ u64 req_data = ((u64)le32_to_cpu(req_desc->u.high) << 32) |
+ le32_to_cpu(req_desc->u.low);
unsigned long flags;
- spin_lock_irqsave(>hba_lock, flags);
- writel(le32_to_cpu(req_desc->u.low),
- >reg_set->inbound_low_queue_port);
- writel(le32_to_cpu(req_desc->u.high),
- >reg_set->inbound_high_queue_port);
- spin_unlock_irqrestore(>hba_lock, flags);
-#endif
+
+ if (dev_64bit_mmio_supported(>pdev->dev)) {
+ writeq(req_data, >reg_set->inbound_low_queue_port);
+ } else {
+ spin_lock_irqsave(>hba_lock, flags);
+ lo_hi_writeq(req_data,
>reg_set->inbound_low_queue_port);
+ spin_unlock_irqrestore(>hba_lock, flags);
+ }
}
/**
--
2.30.1
