* [PATCH] PCI/VPD: Use unaligned access helper in pci_vpd_write
@ 2021-04-18 9:19 Heiner Kallweit
2021-04-19 11:10 ` Heiner Kallweit
2021-04-30 20:29 ` Bjorn Helgaas
0 siblings, 2 replies; 5+ messages in thread
From: Heiner Kallweit @ 2021-04-18 9:19 UTC (permalink / raw)
To: Bjorn Helgaas; +Cc: linux-pci
Use helper get_unaligned_le32() to simplify the code.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
drivers/pci/vpd.c | 15 +++++----------
1 file changed, 5 insertions(+), 10 deletions(-)
diff --git a/drivers/pci/vpd.c b/drivers/pci/vpd.c
index 60573f27a..2888bb300 100644
--- a/drivers/pci/vpd.c
+++ b/drivers/pci/vpd.c
@@ -9,6 +9,7 @@
#include <linux/delay.h>
#include <linux/export.h>
#include <linux/sched/signal.h>
+#include <asm/unaligned.h>
#include "pci.h"
/* VPD access through PCI 2.2+ VPD capability */
@@ -235,10 +236,9 @@ static ssize_t pci_vpd_read(struct pci_dev *dev, loff_t pos, size_t count,
}
static ssize_t pci_vpd_write(struct pci_dev *dev, loff_t pos, size_t count,
- const void *arg)
+ const void *buf)
{
struct pci_vpd *vpd = dev->vpd;
- const u8 *buf = arg;
loff_t end = pos + count;
int ret = 0;
@@ -264,14 +264,8 @@ static ssize_t pci_vpd_write(struct pci_dev *dev, loff_t pos, size_t count,
goto out;
while (pos < end) {
- u32 val;
-
- val = *buf++;
- val |= *buf++ << 8;
- val |= *buf++ << 16;
- val |= *buf++ << 24;
-
- ret = pci_user_write_config_dword(dev, vpd->cap + PCI_VPD_DATA, val);
+ ret = pci_user_write_config_dword(dev, vpd->cap + PCI_VPD_DATA,
+ get_unaligned_le32(buf));
if (ret < 0)
break;
ret = pci_user_write_config_word(dev, vpd->cap + PCI_VPD_ADDR,
@@ -286,6 +280,7 @@ static ssize_t pci_vpd_write(struct pci_dev *dev, loff_t pos, size_t count,
break;
pos += sizeof(u32);
+ buf += sizeof(u32);
}
out:
mutex_unlock(&vpd->lock);
--
2.31.1
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] PCI/VPD: Use unaligned access helper in pci_vpd_write
2021-04-18 9:19 [PATCH] PCI/VPD: Use unaligned access helper in pci_vpd_write Heiner Kallweit
@ 2021-04-19 11:10 ` Heiner Kallweit
2021-04-19 11:31 ` Heiner Kallweit
2021-04-30 20:29 ` Bjorn Helgaas
1 sibling, 1 reply; 5+ messages in thread
From: Heiner Kallweit @ 2021-04-19 11:10 UTC (permalink / raw)
To: Bjorn Helgaas; +Cc: linux-pci
On 18.04.2021 11:19, Heiner Kallweit wrote:
> Use helper get_unaligned_le32() to simplify the code.
>
> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
> ---
> drivers/pci/vpd.c | 15 +++++----------
> 1 file changed, 5 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/pci/vpd.c b/drivers/pci/vpd.c
> index 60573f27a..2888bb300 100644
> --- a/drivers/pci/vpd.c
> +++ b/drivers/pci/vpd.c
> @@ -9,6 +9,7 @@
> #include <linux/delay.h>
> #include <linux/export.h>
> #include <linux/sched/signal.h>
> +#include <asm/unaligned.h>
> #include "pci.h"
>
> /* VPD access through PCI 2.2+ VPD capability */
> @@ -235,10 +236,9 @@ static ssize_t pci_vpd_read(struct pci_dev *dev, loff_t pos, size_t count,
> }
>
> static ssize_t pci_vpd_write(struct pci_dev *dev, loff_t pos, size_t count,
> - const void *arg)
> + const void *buf)
> {
> struct pci_vpd *vpd = dev->vpd;
> - const u8 *buf = arg;
> loff_t end = pos + count;
> int ret = 0;
>
> @@ -264,14 +264,8 @@ static ssize_t pci_vpd_write(struct pci_dev *dev, loff_t pos, size_t count,
> goto out;
>
> while (pos < end) {
> - u32 val;
> -
> - val = *buf++;
> - val |= *buf++ << 8;
> - val |= *buf++ << 16;
> - val |= *buf++ << 24;
> -
> - ret = pci_user_write_config_dword(dev, vpd->cap + PCI_VPD_DATA, val);
> + ret = pci_user_write_config_dword(dev, vpd->cap + PCI_VPD_DATA,
> + get_unaligned_le32(buf));
> if (ret < 0)
> break;
> ret = pci_user_write_config_word(dev, vpd->cap + PCI_VPD_ADDR,
> @@ -286,6 +280,7 @@ static ssize_t pci_vpd_write(struct pci_dev *dev, loff_t pos, size_t count,
> break;
>
> pos += sizeof(u32);
> + buf += sizeof(u32);
> }
> out:
> mutex_unlock(&vpd->lock);
>
Please disregard this patch. According to PCI 2.2 spec the address needs to be dword-aligned.
I will address this in a separate patch.
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] PCI/VPD: Use unaligned access helper in pci_vpd_write
2021-04-19 11:10 ` Heiner Kallweit
@ 2021-04-19 11:31 ` Heiner Kallweit
0 siblings, 0 replies; 5+ messages in thread
From: Heiner Kallweit @ 2021-04-19 11:31 UTC (permalink / raw)
To: Bjorn Helgaas; +Cc: linux-pci
On 19.04.2021 13:10, Heiner Kallweit wrote:
> On 18.04.2021 11:19, Heiner Kallweit wrote:
>> Use helper get_unaligned_le32() to simplify the code.
>>
>> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
>> ---
>> drivers/pci/vpd.c | 15 +++++----------
>> 1 file changed, 5 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/pci/vpd.c b/drivers/pci/vpd.c
>> index 60573f27a..2888bb300 100644
>> --- a/drivers/pci/vpd.c
>> +++ b/drivers/pci/vpd.c
>> @@ -9,6 +9,7 @@
>> #include <linux/delay.h>
>> #include <linux/export.h>
>> #include <linux/sched/signal.h>
>> +#include <asm/unaligned.h>
>> #include "pci.h"
>>
>> /* VPD access through PCI 2.2+ VPD capability */
>> @@ -235,10 +236,9 @@ static ssize_t pci_vpd_read(struct pci_dev *dev, loff_t pos, size_t count,
>> }
>>
>> static ssize_t pci_vpd_write(struct pci_dev *dev, loff_t pos, size_t count,
>> - const void *arg)
>> + const void *buf)
>> {
>> struct pci_vpd *vpd = dev->vpd;
>> - const u8 *buf = arg;
>> loff_t end = pos + count;
>> int ret = 0;
>>
>> @@ -264,14 +264,8 @@ static ssize_t pci_vpd_write(struct pci_dev *dev, loff_t pos, size_t count,
>> goto out;
>>
>> while (pos < end) {
>> - u32 val;
>> -
>> - val = *buf++;
>> - val |= *buf++ << 8;
>> - val |= *buf++ << 16;
>> - val |= *buf++ << 24;
>> -
>> - ret = pci_user_write_config_dword(dev, vpd->cap + PCI_VPD_DATA, val);
>> + ret = pci_user_write_config_dword(dev, vpd->cap + PCI_VPD_DATA,
>> + get_unaligned_le32(buf));
>> if (ret < 0)
>> break;
>> ret = pci_user_write_config_word(dev, vpd->cap + PCI_VPD_ADDR,
>> @@ -286,6 +280,7 @@ static ssize_t pci_vpd_write(struct pci_dev *dev, loff_t pos, size_t count,
>> break;
>>
>> pos += sizeof(u32);
>> + buf += sizeof(u32);
>> }
>> out:
>> mutex_unlock(&vpd->lock);
>>
>
> Please disregard this patch. According to PCI 2.2 spec the address needs to be dword-aligned.
> I will address this in a separate patch.
>
Sorry, I just confused something and wrote before finished thinking. The change is correct.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] PCI/VPD: Use unaligned access helper in pci_vpd_write
2021-04-18 9:19 [PATCH] PCI/VPD: Use unaligned access helper in pci_vpd_write Heiner Kallweit
2021-04-19 11:10 ` Heiner Kallweit
@ 2021-04-30 20:29 ` Bjorn Helgaas
2021-04-30 20:35 ` Heiner Kallweit
1 sibling, 1 reply; 5+ messages in thread
From: Bjorn Helgaas @ 2021-04-30 20:29 UTC (permalink / raw)
To: Heiner Kallweit; +Cc: Bjorn Helgaas, linux-pci
On Sun, Apr 18, 2021 at 11:19:29AM +0200, Heiner Kallweit wrote:
> Use helper get_unaligned_le32() to simplify the code.
>
> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
> ---
> drivers/pci/vpd.c | 15 +++++----------
> 1 file changed, 5 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/pci/vpd.c b/drivers/pci/vpd.c
> index 60573f27a..2888bb300 100644
> --- a/drivers/pci/vpd.c
> +++ b/drivers/pci/vpd.c
> @@ -9,6 +9,7 @@
> #include <linux/delay.h>
> #include <linux/export.h>
> #include <linux/sched/signal.h>
> +#include <asm/unaligned.h>
> #include "pci.h"
>
> /* VPD access through PCI 2.2+ VPD capability */
> @@ -235,10 +236,9 @@ static ssize_t pci_vpd_read(struct pci_dev *dev, loff_t pos, size_t count,
> }
>
> static ssize_t pci_vpd_write(struct pci_dev *dev, loff_t pos, size_t count,
> - const void *arg)
> + const void *buf)
> {
> struct pci_vpd *vpd = dev->vpd;
> - const u8 *buf = arg;
> loff_t end = pos + count;
> int ret = 0;
>
> @@ -264,14 +264,8 @@ static ssize_t pci_vpd_write(struct pci_dev *dev, loff_t pos, size_t count,
> goto out;
>
> while (pos < end) {
> - u32 val;
> -
> - val = *buf++;
> - val |= *buf++ << 8;
> - val |= *buf++ << 16;
> - val |= *buf++ << 24;
> -
> - ret = pci_user_write_config_dword(dev, vpd->cap + PCI_VPD_DATA, val);
> + ret = pci_user_write_config_dword(dev, vpd->cap + PCI_VPD_DATA,
> + get_unaligned_le32(buf));
If I understand correctly, get_unaligned_le32() is equivalent to the
open-coded "val = *buf++; ..." In other words, this doesn't fix a bug
on any platforms, and it doesn't change the bits written to VPD.
Right?
If so, this makes sense. I'd like it better if we could also make
pci_vpd_read() look more symmetric, since it has similar byte
order-related code. The read side is a little more complicated since
the size need not be 4-byte aligned. But maybe there's a way? Seems
like there should be other examples of this sort of thing, but my
quick look didn't find one.
> if (ret < 0)
> break;
> ret = pci_user_write_config_word(dev, vpd->cap + PCI_VPD_ADDR,
> @@ -286,6 +280,7 @@ static ssize_t pci_vpd_write(struct pci_dev *dev, loff_t pos, size_t count,
> break;
>
> pos += sizeof(u32);
> + buf += sizeof(u32);
> }
> out:
> mutex_unlock(&vpd->lock);
> --
> 2.31.1
>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] PCI/VPD: Use unaligned access helper in pci_vpd_write
2021-04-30 20:29 ` Bjorn Helgaas
@ 2021-04-30 20:35 ` Heiner Kallweit
0 siblings, 0 replies; 5+ messages in thread
From: Heiner Kallweit @ 2021-04-30 20:35 UTC (permalink / raw)
To: Bjorn Helgaas; +Cc: Bjorn Helgaas, linux-pci
On 30.04.2021 22:29, Bjorn Helgaas wrote:
> On Sun, Apr 18, 2021 at 11:19:29AM +0200, Heiner Kallweit wrote:
>> Use helper get_unaligned_le32() to simplify the code.
>>
>> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
>> ---
>> drivers/pci/vpd.c | 15 +++++----------
>> 1 file changed, 5 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/pci/vpd.c b/drivers/pci/vpd.c
>> index 60573f27a..2888bb300 100644
>> --- a/drivers/pci/vpd.c
>> +++ b/drivers/pci/vpd.c
>> @@ -9,6 +9,7 @@
>> #include <linux/delay.h>
>> #include <linux/export.h>
>> #include <linux/sched/signal.h>
>> +#include <asm/unaligned.h>
>> #include "pci.h"
>>
>> /* VPD access through PCI 2.2+ VPD capability */
>> @@ -235,10 +236,9 @@ static ssize_t pci_vpd_read(struct pci_dev *dev, loff_t pos, size_t count,
>> }
>>
>> static ssize_t pci_vpd_write(struct pci_dev *dev, loff_t pos, size_t count,
>> - const void *arg)
>> + const void *buf)
>> {
>> struct pci_vpd *vpd = dev->vpd;
>> - const u8 *buf = arg;
>> loff_t end = pos + count;
>> int ret = 0;
>>
>> @@ -264,14 +264,8 @@ static ssize_t pci_vpd_write(struct pci_dev *dev, loff_t pos, size_t count,
>> goto out;
>>
>> while (pos < end) {
>> - u32 val;
>> -
>> - val = *buf++;
>> - val |= *buf++ << 8;
>> - val |= *buf++ << 16;
>> - val |= *buf++ << 24;
>> -
>> - ret = pci_user_write_config_dword(dev, vpd->cap + PCI_VPD_DATA, val);
>> + ret = pci_user_write_config_dword(dev, vpd->cap + PCI_VPD_DATA,
>> + get_unaligned_le32(buf));
>
> If I understand correctly, get_unaligned_le32() is equivalent to the
> open-coded "val = *buf++; ..." In other words, this doesn't fix a bug
> on any platforms, and it doesn't change the bits written to VPD.
> Right?
>
Right.
> If so, this makes sense. I'd like it better if we could also make
> pci_vpd_read() look more symmetric, since it has similar byte
> order-related code. The read side is a little more complicated since
> the size need not be 4-byte aligned. But maybe there's a way? Seems
> like there should be other examples of this sort of thing, but my
> quick look didn't find one.
>
I also find the read side a little bit hard to understand.
Let me check whether I find some way to improve the code.
>> if (ret < 0)
>> break;
>> ret = pci_user_write_config_word(dev, vpd->cap + PCI_VPD_ADDR,
>> @@ -286,6 +280,7 @@ static ssize_t pci_vpd_write(struct pci_dev *dev, loff_t pos, size_t count,
>> break;
>>
>> pos += sizeof(u32);
>> + buf += sizeof(u32);
>> }
>> out:
>> mutex_unlock(&vpd->lock);
>> --
>> 2.31.1
>>
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-04-30 20:35 UTC | newest]
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2021-04-18 9:19 [PATCH] PCI/VPD: Use unaligned access helper in pci_vpd_write Heiner Kallweit
2021-04-19 11:10 ` Heiner Kallweit
2021-04-19 11:31 ` Heiner Kallweit
2021-04-30 20:29 ` Bjorn Helgaas
2021-04-30 20:35 ` Heiner Kallweit
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