[PATCH 0/3] Revert MSI msg API churn

[PATCH 0/3] Revert MSI msg API churn

[Alex Williamson]

The MSI message API has gone through some churn, that I think results
in an inconsistent interface.  We now have this:

void read_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
void get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
void __write_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
void write_msi_msg(unsigned int irq, struct msi_msg *msg);

write_msi_msg() takes an irq arg, but read_msi_msg() takes an
msi_desc.  Presumably write_msi_msg() was not converted because it
has a much larger user base, but this sort of inconsitency results
in a poor API.

This series reverts a selection of commits to return us to:

void __read_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
void __get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
void __write_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg);
void write_msi_msg(unsigned int irq, struct msi_msg *msg);

I've left the removal of read_msi_msg() since it has no users, but
restored get_cached_msi_msg() since it has an imminent user.  This
will also cleanup the upcoming merge conflicts in next.  Thanks,

Alex

---

Alex Williamson (3):
      Revert "PCI/MSI: Remove unused get_cached_msi_msg()"
      Revert "PCI/MSI: Rename __get_cached_msi_msg() to get_cached_msi_msg()"
      Revert "PCI/MSI: Rename __read_msi_msg() to read_msi_msg()"


 arch/ia64/kernel/msi_ia64.c          |    2 +-
 arch/ia64/sn/kernel/msi_sn.c         |    2 +-
 arch/powerpc/platforms/pseries/msi.c |    2 +-
 arch/x86/kernel/apic/io_apic.c       |    2 +-
 arch/x86/pci/xen.c                   |    2 +-
 drivers/pci/msi.c                    |   11 +++++++++--
 include/linux/msi.h                  |    5 +++--
 7 files changed, 17 insertions(+), 9 deletions(-)

[PATCH 1/3] Revert "PCI/MSI: Rename __read_msi_msg() to read_msi_msg()"

[Alex Williamson]

This makes for an inconsistent MSI API, read_msi_msg() takes an
msi_desc arg, but write_msi_msg() takes an irq.  Let's keep the
API consistent that the __read/write interfaces take an msi_desc
and the standard interfaces take an irq.

This reverts 09d4ecd3f067e307211882412f8acd09daaacca2

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---

 arch/powerpc/platforms/pseries/msi.c |    2 +-
 arch/x86/pci/xen.c                   |    2 +-
 drivers/pci/msi.c                    |    2 +-
 include/linux/msi.h                  |    2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/msi.c b/arch/powerpc/platforms/pseries/msi.c
index 88f14a6..8ab5add 100644
--- a/arch/powerpc/platforms/pseries/msi.c
+++ b/arch/powerpc/platforms/pseries/msi.c
@@ -476,7 +476,7 @@ again:
 		irq_set_msi_desc(virq, entry);
 
 		/* Read config space back so we can restore after reset */
-		read_msi_msg(entry, &msg);
+		__read_msi_msg(entry, &msg);
 		entry->msg = msg;
 	}
 
diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
index ad03739..093f5f4 100644
--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c
@@ -229,7 +229,7 @@ static int xen_hvm_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
 		return 1;
 
 	list_for_each_entry(msidesc, &dev->msi_list, list) {
-		read_msi_msg(msidesc, &msg);
+		__read_msi_msg(msidesc, &msg);
 		pirq = MSI_ADDR_EXT_DEST_ID(msg.address_hi) |
 			((msg.address_lo >> MSI_ADDR_DEST_ID_SHIFT) & 0xff);
 		if (msg.data != XEN_PIRQ_MSI_DATA ||
diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index b6565ea..12d0f29 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -249,7 +249,7 @@ void default_restore_msi_irqs(struct pci_dev *dev)
 	}
 }
 
-void read_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
+void __read_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
 {
 	BUG_ON(entry->dev->current_state != PCI_D0);
 
diff --git a/include/linux/msi.h b/include/linux/msi.h
index 36c63cf..0bb302f 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -15,7 +15,7 @@ struct irq_data;
 struct msi_desc;
 void mask_msi_irq(struct irq_data *data);
 void unmask_msi_irq(struct irq_data *data);
-void read_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
+void __read_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
 void get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
 void __write_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
 void write_msi_msg(unsigned int irq, struct msi_msg *msg);

[PATCH 2/3] Revert "PCI/MSI: Rename __get_cached_msi_msg() to get_cached_msi_msg()"

[Alex Williamson]

This is another case of making the MSI msg API inconsistent, for
seemingly no gain.  Continue to use __get_cached_msi_msg() with an
msi_desc and leave get_cached_msi_msg() for an irq interfaces.

This reverts 18ef822c59f60d52c8534b295086d38e9e8e0f7d

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---

 arch/ia64/kernel/msi_ia64.c    |    2 +-
 arch/ia64/sn/kernel/msi_sn.c   |    2 +-
 arch/x86/kernel/apic/io_apic.c |    2 +-
 drivers/pci/msi.c              |    2 +-
 include/linux/msi.h            |    2 +-
 5 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/ia64/kernel/msi_ia64.c b/arch/ia64/kernel/msi_ia64.c
index 4efe748..8c3730c 100644
--- a/arch/ia64/kernel/msi_ia64.c
+++ b/arch/ia64/kernel/msi_ia64.c
@@ -23,7 +23,7 @@ static int ia64_set_msi_irq_affinity(struct irq_data *idata,
 	if (irq_prepare_move(irq, cpu))
 		return -1;
 
-	get_cached_msi_msg(idata->msi_desc, &msg);
+	__get_cached_msi_msg(idata->msi_desc, &msg);
 
 	addr = msg.address_lo;
 	addr &= MSI_ADDR_DEST_ID_MASK;
diff --git a/arch/ia64/sn/kernel/msi_sn.c b/arch/ia64/sn/kernel/msi_sn.c
index 8bec242..446e779 100644
--- a/arch/ia64/sn/kernel/msi_sn.c
+++ b/arch/ia64/sn/kernel/msi_sn.c
@@ -175,7 +175,7 @@ static int sn_set_msi_irq_affinity(struct irq_data *data,
 	 * Release XIO resources for the old MSI PCI address
 	 */
 
-	get_cached_msi_msg(data->msi_desc, &msg);
+	__get_cached_msi_msg(data->msi_desc, &msg);
 	sn_pdev = (struct pcidev_info *)sn_irq_info->irq_pciioinfo;
 	pdev = sn_pdev->pdi_linux_pcidev;
 	provider = SN_PCIDEV_BUSPROVIDER(pdev);
diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index e877cfb..29290f5 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -3145,7 +3145,7 @@ msi_set_affinity(struct irq_data *data, const struct cpumask *mask, bool force)
 	if (ret)
 		return ret;
 
-	get_cached_msi_msg(data->msi_desc, &msg);
+	__get_cached_msi_msg(data->msi_desc, &msg);
 
 	msg.data &= ~MSI_DATA_VECTOR_MASK;
 	msg.data |= MSI_DATA_VECTOR(cfg->vector);
diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 12d0f29..2bd0fbe 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -279,7 +279,7 @@ void __read_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
 	}
 }
 
-void get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
+void __get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
 {
 	/* Assert that the cache is valid, assuming that
 	 * valid messages are not all-zeroes. */
diff --git a/include/linux/msi.h b/include/linux/msi.h
index 0bb302f..d0e0cfe 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -16,7 +16,7 @@ struct msi_desc;
 void mask_msi_irq(struct irq_data *data);
 void unmask_msi_irq(struct irq_data *data);
 void __read_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
-void get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
+void __get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
 void __write_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
 void write_msi_msg(unsigned int irq, struct msi_msg *msg);
 

[PATCH 3/3] Revert "PCI/MSI: Remove unused get_cached_msi_msg()"

[Alex Williamson]

We have an upcoming merge collision with code that actually does use
this, b8f02af096b1fc9fd46680cbe55214e477eb76d3.  Restore this function
in advance of the merge.

This reverts a160fe94cb533a438258642d8d5b2b3795497341

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---

 drivers/pci/msi.c   |    7 +++++++
 include/linux/msi.h |    1 +
 2 files changed, 8 insertions(+)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 2bd0fbe..12fdb27 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -289,6 +289,13 @@ void __get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
 	*msg = entry->msg;
 }
 
+void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg)
+{
+	struct msi_desc *entry = irq_get_msi_desc(irq);
+
+	__get_cached_msi_msg(entry, msg);
+}
+
 void __write_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
 {
 	if (entry->dev->current_state != PCI_D0) {
diff --git a/include/linux/msi.h b/include/linux/msi.h
index d0e0cfe..fb35a71 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -18,6 +18,7 @@ void unmask_msi_irq(struct irq_data *data);
 void __read_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
 void __get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
 void __write_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
+void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg);
 void write_msi_msg(unsigned int irq, struct msi_msg *msg);
 
 struct msi_desc {

Re: [PATCH 0/3] Revert MSI msg API churn

[Bjorn Helgaas]

On Wed, Oct 01, 2014 at 10:48:16AM -0600, Alex Williamson wrote:
> The MSI message API has gone through some churn, that I think results
> in an inconsistent interface.  We now have this:
> 
> void read_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
> void get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
> void __write_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
> void write_msi_msg(unsigned int irq, struct msi_msg *msg);
> 
> write_msi_msg() takes an irq arg, but read_msi_msg() takes an
> msi_desc.  Presumably write_msi_msg() was not converted because it
> has a much larger user base, but this sort of inconsitency results
> in a poor API.

Yeah, that isn't good, thanks for noticing.

I rebuilt the pci/msi branch and dropped the commits you mentioned.
The ones that are left are these:

  56b72b409579 PCI/MSI: Use __write_msi_msg() instead of write_msi_msg()
  1e8f4cc82ede MSI/powerpc: Use __read_msi_msg() instead of read_msi_msg()
  2b260085e466 PCI/MSI: Use __get_cached_msi_msg() instead of get_cached_msi_msg()

which I think are OK.

> This series reverts a selection of commits to return us to:
> 
> void __read_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
> void __get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
> void __write_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
> void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg);
> void write_msi_msg(unsigned int irq, struct msi_msg *msg);
> 
> I've left the removal of read_msi_msg() since it has no users, but
> restored get_cached_msi_msg() since it has an imminent user.  This
> will also cleanup the upcoming merge conflicts in next.  Thanks,
> 
> Alex
> 
> ---
> 
> Alex Williamson (3):
>       Revert "PCI/MSI: Remove unused get_cached_msi_msg()"
>       Revert "PCI/MSI: Rename __get_cached_msi_msg() to get_cached_msi_msg()"
>       Revert "PCI/MSI: Rename __read_msi_msg() to read_msi_msg()"
> 
> 
>  arch/ia64/kernel/msi_ia64.c          |    2 +-
>  arch/ia64/sn/kernel/msi_sn.c         |    2 +-
>  arch/powerpc/platforms/pseries/msi.c |    2 +-
>  arch/x86/kernel/apic/io_apic.c       |    2 +-
>  arch/x86/pci/xen.c                   |    2 +-
>  drivers/pci/msi.c                    |   11 +++++++++--
>  include/linux/msi.h                  |    5 +++--
>  7 files changed, 17 insertions(+), 9 deletions(-)