pci_intx() is a hybrid function which sometimes performs devres
operations, depending on whether pcim_enable_device() has been used to
enable the pci_dev. This sometimes-managed nature of the function is
problematic. Notably, it causes the function to allocate under some
circumstances which makes it unusable from interrupt context.
To, ultimately, remove the hybrid nature from pci_intx(), it is first
necessary to provide an always-managed and a never-managed version
of that function. Then, all callers of pci_intx() can be ported to the
version they need, depending whether they use pci_enable_device() or
pcim_enable_device().
An always-managed function exists, namely pcim_intx(), for which
__pcim_intx(), a never-managed version of pci_intx() had been
implemented.
Make __pcim_intx() a public function under the name
pci_intx_unmanaged(). Make pcim_intx() a public function.
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
---
drivers/pci/devres.c | 24 +++---------------------
drivers/pci/pci.c | 26 ++++++++++++++++++++++++++
include/linux/pci.h | 2 ++
3 files changed, 31 insertions(+), 21 deletions(-)
diff --git a/drivers/pci/devres.c b/drivers/pci/devres.c
index b133967faef8..475a3ae5c33f 100644
--- a/drivers/pci/devres.c
+++ b/drivers/pci/devres.c
@@ -411,31 +411,12 @@ static inline bool mask_contains_bar(int mask, int bar)
return mask & BIT(bar);
}
-/*
- * This is a copy of pci_intx() used to bypass the problem of recursive
- * function calls due to the hybrid nature of pci_intx().
- */
-static void __pcim_intx(struct pci_dev *pdev, int enable)
-{
- u16 pci_command, new;
-
- pci_read_config_word(pdev, PCI_COMMAND, &pci_command);
-
- if (enable)
- new = pci_command & ~PCI_COMMAND_INTX_DISABLE;
- else
- new = pci_command | PCI_COMMAND_INTX_DISABLE;
-
- if (new != pci_command)
- pci_write_config_word(pdev, PCI_COMMAND, new);
-}
-
static void pcim_intx_restore(struct device *dev, void *data)
{
struct pci_dev *pdev = to_pci_dev(dev);
struct pcim_intx_devres *res = data;
- __pcim_intx(pdev, res->orig_intx);
+ pci_intx_unmanaged(pdev, res->orig_intx);
}
static struct pcim_intx_devres *get_or_create_intx_devres(struct device *dev)
@@ -472,10 +453,11 @@ int pcim_intx(struct pci_dev *pdev, int enable)
return -ENOMEM;
res->orig_intx = !enable;
- __pcim_intx(pdev, enable);
+ pci_intx_unmanaged(pdev, enable);
return 0;
}
+EXPORT_SYMBOL(pcim_intx);
static void pcim_disable_device(void *pdev_raw)
{
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 7d85c04fbba2..318cfb5b5e15 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4476,6 +4476,32 @@ void pci_disable_parity(struct pci_dev *dev)
}
}
+/**
+ * pci_intx - enables/disables PCI INTx for device dev, unmanaged version
+ * @pdev: the PCI device to operate on
+ * @enable: boolean: whether to enable or disable PCI INTx
+ *
+ * Enables/disables PCI INTx for device @pdev
+ *
+ * This function behavios identically to pci_intx(), but is never managed with
+ * devres.
+ */
+void pci_intx_unmanaged(struct pci_dev *pdev, int enable)
+{
+ u16 pci_command, new;
+
+ pci_read_config_word(pdev, PCI_COMMAND, &pci_command);
+
+ if (enable)
+ new = pci_command & ~PCI_COMMAND_INTX_DISABLE;
+ else
+ new = pci_command | PCI_COMMAND_INTX_DISABLE;
+
+ if (new != pci_command)
+ pci_write_config_word(pdev, PCI_COMMAND, new);
+}
+EXPORT_SYMBOL_GPL(pci_intx_unmanaged);
+
/**
* pci_intx - enables/disables PCI INTx for device dev
* @pdev: the PCI device to operate on
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 573b4c4c2be6..6b8cde76d564 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1353,6 +1353,7 @@ int __must_check pcim_set_mwi(struct pci_dev *dev);
int pci_try_set_mwi(struct pci_dev *dev);
void pci_clear_mwi(struct pci_dev *dev);
void pci_disable_parity(struct pci_dev *dev);
+void pci_intx_unmanaged(struct pci_dev *pdev, int enable);
void pci_intx(struct pci_dev *dev, int enable);
bool pci_check_and_mask_intx(struct pci_dev *dev);
bool pci_check_and_unmask_intx(struct pci_dev *dev);
@@ -2293,6 +2294,7 @@ static inline void pci_fixup_device(enum pci_fixup_pass pass,
struct pci_dev *dev) { }
#endif
+int pcim_intx(struct pci_dev *pdev, int enabled);
void __iomem *pcim_iomap(struct pci_dev *pdev, int bar, unsigned long maxlen);
void __iomem *pcim_iomap_region(struct pci_dev *pdev, int bar,
const char *name);
--
2.46.1On Wed, 9 Oct 2024 10:35:07 +0200
Philipp Stanner <pstanner@redhat.com> wrote:
> pci_intx() is a hybrid function which sometimes performs devres
> operations, depending on whether pcim_enable_device() has been used to
> enable the pci_dev. This sometimes-managed nature of the function is
> problematic. Notably, it causes the function to allocate under some
> circumstances which makes it unusable from interrupt context.
>
> To, ultimately, remove the hybrid nature from pci_intx(), it is first
> necessary to provide an always-managed and a never-managed version
> of that function. Then, all callers of pci_intx() can be ported to the
> version they need, depending whether they use pci_enable_device() or
> pcim_enable_device().
>
> An always-managed function exists, namely pcim_intx(), for which
> __pcim_intx(), a never-managed version of pci_intx() had been
> implemented.
>
> Make __pcim_intx() a public function under the name
> pci_intx_unmanaged(). Make pcim_intx() a public function.
>
> Signed-off-by: Philipp Stanner <pstanner@redhat.com>
> ---
> drivers/pci/devres.c | 24 +++---------------------
> drivers/pci/pci.c | 26 ++++++++++++++++++++++++++
> include/linux/pci.h | 2 ++
> 3 files changed, 31 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/pci/devres.c b/drivers/pci/devres.c
> index b133967faef8..475a3ae5c33f 100644
> --- a/drivers/pci/devres.c
> +++ b/drivers/pci/devres.c
> @@ -411,31 +411,12 @@ static inline bool mask_contains_bar(int mask, int bar)
> return mask & BIT(bar);
> }
>
> -/*
> - * This is a copy of pci_intx() used to bypass the problem of recursive
> - * function calls due to the hybrid nature of pci_intx().
> - */
> -static void __pcim_intx(struct pci_dev *pdev, int enable)
> -{
> - u16 pci_command, new;
> -
> - pci_read_config_word(pdev, PCI_COMMAND, &pci_command);
> -
> - if (enable)
> - new = pci_command & ~PCI_COMMAND_INTX_DISABLE;
> - else
> - new = pci_command | PCI_COMMAND_INTX_DISABLE;
> -
> - if (new != pci_command)
> - pci_write_config_word(pdev, PCI_COMMAND, new);
> -}
> -
> static void pcim_intx_restore(struct device *dev, void *data)
> {
> struct pci_dev *pdev = to_pci_dev(dev);
> struct pcim_intx_devres *res = data;
>
> - __pcim_intx(pdev, res->orig_intx);
> + pci_intx_unmanaged(pdev, res->orig_intx);
> }
>
> static struct pcim_intx_devres *get_or_create_intx_devres(struct device *dev)
> @@ -472,10 +453,11 @@ int pcim_intx(struct pci_dev *pdev, int enable)
> return -ENOMEM;
>
> res->orig_intx = !enable;
> - __pcim_intx(pdev, enable);
> + pci_intx_unmanaged(pdev, enable);
>
> return 0;
> }
> +EXPORT_SYMBOL(pcim_intx);
What precludes this from _GPL? Also note that this is now calling a
GPL symbol, so by default I'd assume it should also be GPL. Thanks,
Alex
>
> static void pcim_disable_device(void *pdev_raw)
> {
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 7d85c04fbba2..318cfb5b5e15 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -4476,6 +4476,32 @@ void pci_disable_parity(struct pci_dev *dev)
> }
> }
>
> +/**
> + * pci_intx - enables/disables PCI INTx for device dev, unmanaged version
> + * @pdev: the PCI device to operate on
> + * @enable: boolean: whether to enable or disable PCI INTx
> + *
> + * Enables/disables PCI INTx for device @pdev
> + *
> + * This function behavios identically to pci_intx(), but is never managed with
> + * devres.
> + */
> +void pci_intx_unmanaged(struct pci_dev *pdev, int enable)
> +{
> + u16 pci_command, new;
> +
> + pci_read_config_word(pdev, PCI_COMMAND, &pci_command);
> +
> + if (enable)
> + new = pci_command & ~PCI_COMMAND_INTX_DISABLE;
> + else
> + new = pci_command | PCI_COMMAND_INTX_DISABLE;
> +
> + if (new != pci_command)
> + pci_write_config_word(pdev, PCI_COMMAND, new);
> +}
> +EXPORT_SYMBOL_GPL(pci_intx_unmanaged);
> +
> /**
> * pci_intx - enables/disables PCI INTx for device dev
> * @pdev: the PCI device to operate on
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 573b4c4c2be6..6b8cde76d564 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1353,6 +1353,7 @@ int __must_check pcim_set_mwi(struct pci_dev *dev);
> int pci_try_set_mwi(struct pci_dev *dev);
> void pci_clear_mwi(struct pci_dev *dev);
> void pci_disable_parity(struct pci_dev *dev);
> +void pci_intx_unmanaged(struct pci_dev *pdev, int enable);
> void pci_intx(struct pci_dev *dev, int enable);
> bool pci_check_and_mask_intx(struct pci_dev *dev);
> bool pci_check_and_unmask_intx(struct pci_dev *dev);
> @@ -2293,6 +2294,7 @@ static inline void pci_fixup_device(enum pci_fixup_pass pass,
> struct pci_dev *dev) { }
> #endif
>
> +int pcim_intx(struct pci_dev *pdev, int enabled);
> void __iomem *pcim_iomap(struct pci_dev *pdev, int bar, unsigned long maxlen);
> void __iomem *pcim_iomap_region(struct pci_dev *pdev, int bar,
> const char *name);
On Thu, 2024-10-10 at 11:43 -0600, Alex Williamson wrote:
> On Wed, 9 Oct 2024 10:35:07 +0200
> Philipp Stanner <pstanner@redhat.com> wrote:
>
> > pci_intx() is a hybrid function which sometimes performs devres
> > operations, depending on whether pcim_enable_device() has been used
> > to
> > enable the pci_dev. This sometimes-managed nature of the function
> > is
> > problematic. Notably, it causes the function to allocate under some
> > circumstances which makes it unusable from interrupt context.
> >
> > To, ultimately, remove the hybrid nature from pci_intx(), it is
> > first
> > necessary to provide an always-managed and a never-managed version
> > of that function. Then, all callers of pci_intx() can be ported to
> > the
> > version they need, depending whether they use pci_enable_device()
> > or
> > pcim_enable_device().
> >
> > An always-managed function exists, namely pcim_intx(), for which
> > __pcim_intx(), a never-managed version of pci_intx() had been
> > implemented.
> >
> > Make __pcim_intx() a public function under the name
> > pci_intx_unmanaged(). Make pcim_intx() a public function.
> >
> > Signed-off-by: Philipp Stanner <pstanner@redhat.com>
> > ---
> > drivers/pci/devres.c | 24 +++---------------------
> > drivers/pci/pci.c | 26 ++++++++++++++++++++++++++
> > include/linux/pci.h | 2 ++
> > 3 files changed, 31 insertions(+), 21 deletions(-)
> >
> > diff --git a/drivers/pci/devres.c b/drivers/pci/devres.c
> > index b133967faef8..475a3ae5c33f 100644
> > --- a/drivers/pci/devres.c
> > +++ b/drivers/pci/devres.c
> > @@ -411,31 +411,12 @@ static inline bool mask_contains_bar(int
> > mask, int bar)
> > return mask & BIT(bar);
> > }
> >
> > -/*
> > - * This is a copy of pci_intx() used to bypass the problem of
> > recursive
> > - * function calls due to the hybrid nature of pci_intx().
> > - */
> > -static void __pcim_intx(struct pci_dev *pdev, int enable)
> > -{
> > - u16 pci_command, new;
> > -
> > - pci_read_config_word(pdev, PCI_COMMAND, &pci_command);
> > -
> > - if (enable)
> > - new = pci_command & ~PCI_COMMAND_INTX_DISABLE;
> > - else
> > - new = pci_command | PCI_COMMAND_INTX_DISABLE;
> > -
> > - if (new != pci_command)
> > - pci_write_config_word(pdev, PCI_COMMAND, new);
> > -}
> > -
> > static void pcim_intx_restore(struct device *dev, void *data)
> > {
> > struct pci_dev *pdev = to_pci_dev(dev);
> > struct pcim_intx_devres *res = data;
> >
> > - __pcim_intx(pdev, res->orig_intx);
> > + pci_intx_unmanaged(pdev, res->orig_intx);
> > }
> >
> > static struct pcim_intx_devres *get_or_create_intx_devres(struct
> > device *dev)
> > @@ -472,10 +453,11 @@ int pcim_intx(struct pci_dev *pdev, int
> > enable)
> > return -ENOMEM;
> >
> > res->orig_intx = !enable;
> > - __pcim_intx(pdev, enable);
> > + pci_intx_unmanaged(pdev, enable);
> >
> > return 0;
> > }
> > +EXPORT_SYMBOL(pcim_intx);
>
> What precludes this from _GPL? Also note that this is now calling a
> GPL symbol, so by default I'd assume it should also be GPL. Thanks,
Ah right, I overlooked that pci_intx() also has the _GPL version.
Will make consistent.
Thx,
P.
>
> Alex
>
> >
> > static void pcim_disable_device(void *pdev_raw)
> > {
> > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > index 7d85c04fbba2..318cfb5b5e15 100644
> > --- a/drivers/pci/pci.c
> > +++ b/drivers/pci/pci.c
> > @@ -4476,6 +4476,32 @@ void pci_disable_parity(struct pci_dev *dev)
> > }
> > }
> >
> > +/**
> > + * pci_intx - enables/disables PCI INTx for device dev, unmanaged
> > version
> > + * @pdev: the PCI device to operate on
> > + * @enable: boolean: whether to enable or disable PCI INTx
> > + *
> > + * Enables/disables PCI INTx for device @pdev
> > + *
> > + * This function behavios identically to pci_intx(), but is never
> > managed with
> > + * devres.
> > + */
> > +void pci_intx_unmanaged(struct pci_dev *pdev, int enable)
> > +{
> > + u16 pci_command, new;
> > +
> > + pci_read_config_word(pdev, PCI_COMMAND, &pci_command);
> > +
> > + if (enable)
> > + new = pci_command & ~PCI_COMMAND_INTX_DISABLE;
> > + else
> > + new = pci_command | PCI_COMMAND_INTX_DISABLE;
> > +
> > + if (new != pci_command)
> > + pci_write_config_word(pdev, PCI_COMMAND, new);
> > +}
> > +EXPORT_SYMBOL_GPL(pci_intx_unmanaged);
> > +
> > /**
> > * pci_intx - enables/disables PCI INTx for device dev
> > * @pdev: the PCI device to operate on
> > diff --git a/include/linux/pci.h b/include/linux/pci.h
> > index 573b4c4c2be6..6b8cde76d564 100644
> > --- a/include/linux/pci.h
> > +++ b/include/linux/pci.h
> > @@ -1353,6 +1353,7 @@ int __must_check pcim_set_mwi(struct pci_dev
> > *dev);
> > int pci_try_set_mwi(struct pci_dev *dev);
> > void pci_clear_mwi(struct pci_dev *dev);
> > void pci_disable_parity(struct pci_dev *dev);
> > +void pci_intx_unmanaged(struct pci_dev *pdev, int enable);
> > void pci_intx(struct pci_dev *dev, int enable);
> > bool pci_check_and_mask_intx(struct pci_dev *dev);
> > bool pci_check_and_unmask_intx(struct pci_dev *dev);
> > @@ -2293,6 +2294,7 @@ static inline void pci_fixup_device(enum
> > pci_fixup_pass pass,
> > struct pci_dev *dev) { }
> > #endif
> >
> > +int pcim_intx(struct pci_dev *pdev, int enabled);
> > void __iomem *pcim_iomap(struct pci_dev *pdev, int bar, unsigned
> > long maxlen);
> > void __iomem *pcim_iomap_region(struct pci_dev *pdev, int bar,
> > const char *name);
>
On Wed, Oct 09, 2024 at 10:35:07AM +0200, Philipp Stanner wrote: > pci_intx() is a hybrid function which sometimes performs devres > operations, depending on whether pcim_enable_device() has been used to > enable the pci_dev. This sometimes-managed nature of the function is > problematic. Notably, it causes the function to allocate under some > circumstances which makes it unusable from interrupt context. > > To, ultimately, remove the hybrid nature from pci_intx(), it is first > necessary to provide an always-managed and a never-managed version > of that function. Then, all callers of pci_intx() can be ported to the > version they need, depending whether they use pci_enable_device() or > pcim_enable_device(). > > An always-managed function exists, namely pcim_intx(), for which > __pcim_intx(), a never-managed version of pci_intx() had been > implemented. > Make __pcim_intx() a public function under the name > pci_intx_unmanaged(). Make pcim_intx() a public function. To avoid an additional churn we can make just completely new APIs, namely: pcim_int_x() pci_int_x() You won't need all dirty dances with double underscored function naming and renaming. ... > + pci_read_config_word(pdev, PCI_COMMAND, &pci_command); > + > + if (enable) > + new = pci_command & ~PCI_COMMAND_INTX_DISABLE; > + else > + new = pci_command | PCI_COMMAND_INTX_DISABLE; > + > + if (new != pci_command) I would use positive conditionals as easy to read (yes, a couple of lines longer, but also a win is the indentation and avoiding an additional churn in the future in case we need to add something in this branch. > + pci_write_config_word(pdev, PCI_COMMAND, new); ... Otherwise I'm for the idea in general. -- With Best Regards, Andy Shevchenko
On Thu, 2024-10-10 at 17:40 +0300, Andy Shevchenko wrote:
> On Wed, Oct 09, 2024 at 10:35:07AM +0200, Philipp Stanner wrote:
> > pci_intx() is a hybrid function which sometimes performs devres
> > operations, depending on whether pcim_enable_device() has been used
> > to
> > enable the pci_dev. This sometimes-managed nature of the function
> > is
> > problematic. Notably, it causes the function to allocate under some
> > circumstances which makes it unusable from interrupt context.
> >
> > To, ultimately, remove the hybrid nature from pci_intx(), it is
> > first
> > necessary to provide an always-managed and a never-managed version
> > of that function. Then, all callers of pci_intx() can be ported to
> > the
> > version they need, depending whether they use pci_enable_device()
> > or
> > pcim_enable_device().
> >
> > An always-managed function exists, namely pcim_intx(), for which
> > __pcim_intx(), a never-managed version of pci_intx() had been
> > implemented.
>
> > Make __pcim_intx() a public function under the name
> > pci_intx_unmanaged(). Make pcim_intx() a public function.
>
> To avoid an additional churn we can make just completely new APIs,
> namely:
> pcim_int_x()
> pci_int_x()
>
> You won't need all dirty dances with double underscored function
> naming and
> renaming.
Ähm.. I can't follow. The new version doesn't use double underscores
anymore. __pcim_intx() is being removed, effectively.
After this series, we'd end up with a clean:
pci_intx() <-> pcim_intx()
just as in the other PCI APIs.
>
>
> ...
>
> > + pci_read_config_word(pdev, PCI_COMMAND, &pci_command);
> > +
> > + if (enable)
> > + new = pci_command & ~PCI_COMMAND_INTX_DISABLE;
> > + else
> > + new = pci_command | PCI_COMMAND_INTX_DISABLE;
> > +
> > + if (new != pci_command)
>
> I would use positive conditionals as easy to read (yes, a couple of
> lines
> longer, but also a win is the indentation and avoiding an additional
> churn in
> the future in case we need to add something in this branch.
I can't follow. You mean:
if (new == pci_command)
return;
?
That's exactly the same level of indentation. Plus, I just copied the
code.
>
> > + pci_write_config_word(pdev, PCI_COMMAND, new);
>
> ...
>
> Otherwise I'm for the idea in general.
\o/
>
On Fri, Oct 11, 2024 at 02:16:06PM +0200, Philipp Stanner wrote:
> On Thu, 2024-10-10 at 17:40 +0300, Andy Shevchenko wrote:
> > On Wed, Oct 09, 2024 at 10:35:07AM +0200, Philipp Stanner wrote:
> > > pci_intx() is a hybrid function which sometimes performs devres
> > > operations, depending on whether pcim_enable_device() has been used
> > > to
> > > enable the pci_dev. This sometimes-managed nature of the function
> > > is
> > > problematic. Notably, it causes the function to allocate under some
> > > circumstances which makes it unusable from interrupt context.
> > >
> > > To, ultimately, remove the hybrid nature from pci_intx(), it is
> > > first
> > > necessary to provide an always-managed and a never-managed version
> > > of that function. Then, all callers of pci_intx() can be ported to
> > > the
> > > version they need, depending whether they use pci_enable_device()
> > > or
> > > pcim_enable_device().
> > > An always-managed function exists, namely pcim_intx(), for which
> > > __pcim_intx(), a never-managed version of pci_intx() had been
> > > implemented.
> >
> > > Make __pcim_intx() a public function under the name
> > > pci_intx_unmanaged(). Make pcim_intx() a public function.
It seems I got confused by these two paragraphs. Why the double underscored
function is even mentioned here?
> > To avoid an additional churn we can make just completely new APIs,
> > namely:
> > pcim_int_x()
> > pci_int_x()
> >
> > You won't need all dirty dances with double underscored function
> > naming and
> > renaming.
>
> Ähm.. I can't follow. The new version doesn't use double underscores
> anymore. __pcim_intx() is being removed, effectively.
> After this series, we'd end up with a clean:
>
> pci_intx() <-> pcim_intx()
>
> just as in the other PCI APIs.
...
> > > + pci_read_config_word(pdev, PCI_COMMAND, &pci_command);
> > > +
> > > + if (enable)
> > > + new = pci_command & ~PCI_COMMAND_INTX_DISABLE;
> > > + else
> > > + new = pci_command | PCI_COMMAND_INTX_DISABLE;
> > > +
> > > + if (new != pci_command)
> >
> > I would use positive conditionals as easy to read (yes, a couple of
> > lines
> > longer, but also a win is the indentation and avoiding an additional
> > churn in
> > the future in case we need to add something in this branch.
>
> I can't follow. You mean:
>
> if (new == pci_command)
> return;
>
> ?
>
> That's exactly the same level of indentation.
No, the body gets one level off.
> Plus, I just copied the code.
>
> > > + pci_write_config_word(pdev, PCI_COMMAND, new);
if (new == pci_command)
return;
pci_write_config_word(pdev, PCI_COMMAND, new);
See the difference?
Also, imaging adding a new code in your case:
if (new != pci_command)
pci_write_config_word(pdev, PCI_COMMAND, new);
==>
if (new != pci_command) {
...foo...
pci_write_config_word(pdev, PCI_COMMAND, new);
...bar...
}
And in mine:
if (new == pci_command)
return;
...foo...
pci_write_config_word(pdev, PCI_COMMAND, new);
...bar...
I hope it's clear now what I meant.
--
With Best Regards,
Andy Shevchenko
On Fri, 2024-10-11 at 16:50 +0300, Andy Shevchenko wrote:
> On Fri, Oct 11, 2024 at 02:16:06PM +0200, Philipp Stanner wrote:
> > On Thu, 2024-10-10 at 17:40 +0300, Andy Shevchenko wrote:
> > > On Wed, Oct 09, 2024 at 10:35:07AM +0200, Philipp Stanner wrote:
> > > > pci_intx() is a hybrid function which sometimes performs devres
> > > > operations, depending on whether pcim_enable_device() has been
> > > > used
> > > > to
> > > > enable the pci_dev. This sometimes-managed nature of the
> > > > function
> > > > is
> > > > problematic. Notably, it causes the function to allocate under
> > > > some
> > > > circumstances which makes it unusable from interrupt context.
> > > >
> > > > To, ultimately, remove the hybrid nature from pci_intx(), it is
> > > > first
> > > > necessary to provide an always-managed and a never-managed
> > > > version
> > > > of that function. Then, all callers of pci_intx() can be ported
> > > > to
> > > > the
> > > > version they need, depending whether they use
> > > > pci_enable_device()
> > > > or
> > > > pcim_enable_device().
>
> > > > An always-managed function exists, namely pcim_intx(), for
> > > > which
> > > > __pcim_intx(), a never-managed version of pci_intx() had been
> > > > implemented.
> > >
> > > > Make __pcim_intx() a public function under the name
> > > > pci_intx_unmanaged(). Make pcim_intx() a public function.
>
> It seems I got confused by these two paragraphs. Why the double
> underscored
> function is even mentioned here?
It's mentioned because it's being moved.
>
> > > To avoid an additional churn we can make just completely new
> > > APIs,
> > > namely:
> > > pcim_int_x()
> > > pci_int_x()
> > >
> > > You won't need all dirty dances with double underscored function
> > > naming and
> > > renaming.
> >
> > Ähm.. I can't follow. The new version doesn't use double
> > underscores
> > anymore. __pcim_intx() is being removed, effectively.
> > After this series, we'd end up with a clean:
> >
> > pci_intx() <-> pcim_intx()
> >
> > just as in the other PCI APIs.
>
> ...
>
> > > > + pci_read_config_word(pdev, PCI_COMMAND, &pci_command);
> > > > +
> > > > + if (enable)
> > > > + new = pci_command & ~PCI_COMMAND_INTX_DISABLE;
> > > > + else
> > > > + new = pci_command | PCI_COMMAND_INTX_DISABLE;
> > > > +
> > > > + if (new != pci_command)
> > >
> > > I would use positive conditionals as easy to read (yes, a couple
> > > of
> > > lines
> > > longer, but also a win is the indentation and avoiding an
> > > additional
> > > churn in
> > > the future in case we need to add something in this branch.
> >
> > I can't follow. You mean:
> >
> > if (new == pci_command)
> > return;
> >
> > ?
> >
> > That's exactly the same level of indentation.
>
> No, the body gets one level off.
>
> > Plus, I just copied the code.
> >
> > > > + pci_write_config_word(pdev, PCI_COMMAND, new);
>
> if (new == pci_command)
> return;
>
> pci_write_config_word(pdev, PCI_COMMAND, new);
>
> See the difference?
> Also, imaging adding a new code in your case:
>
> if (new != pci_command)
> pci_write_config_word(pdev, PCI_COMMAND, new);
>
> ==>
>
> if (new != pci_command) {
> ...foo...
> pci_write_config_word(pdev, PCI_COMMAND, new);
> ...bar...
> }
>
> And in mine:
>
> if (new == pci_command)
> return;
>
> ...foo...
> pci_write_config_word(pdev, PCI_COMMAND, new);
> ...bar...
>
> I hope it's clear now what I meant.
It is clear.. I'm not necessarily convinced that it's better to review
than just copying the pre-existing code, but if you really want it we
can do it I guess.
P.
On 10/9/24 17:35, Philipp Stanner wrote: > pci_intx() is a hybrid function which sometimes performs devres > operations, depending on whether pcim_enable_device() has been used to > enable the pci_dev. This sometimes-managed nature of the function is > problematic. Notably, it causes the function to allocate under some > circumstances which makes it unusable from interrupt context. > > To, ultimately, remove the hybrid nature from pci_intx(), it is first > necessary to provide an always-managed and a never-managed version > of that function. Then, all callers of pci_intx() can be ported to the > version they need, depending whether they use pci_enable_device() or > pcim_enable_device(). > > An always-managed function exists, namely pcim_intx(), for which > __pcim_intx(), a never-managed version of pci_intx() had been s/had/has ? Not sure about this, English is not my first language :) > implemented. > > Make __pcim_intx() a public function under the name > pci_intx_unmanaged(). Make pcim_intx() a public function. > > Signed-off-by: Philipp Stanner <pstanner@redhat.com> Regardless of the above nit, looks OK to me. Reviewed-by: Damien Le Moal <dlemoal@kernel.org> -- Damien Le Moal Western Digital Research
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