[PATCH v2 1/3] pci: remove redundant pci_dev_get/put() on kobject (un)register

[PATCH v2 1/3] pci: remove redundant pci_dev_get/put() on kobject (un)register

[Veaceslav Falico]

Currently we're pci_dev_get/put()-ing pci device on every kobject
creation/removal. It's useless per se - the kobject is part of the device
itself, so it should be removed when there are no users of the pdev, and is
not a user of it.

CC: Bjorn Helgaas <bhelgaas@google.com>
CC: Neil Horman <nhorman@tuxdriver.com>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC: linux-pci@vger.kernel.org
CC: linux-kernel@vger.kernel.org
Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
---
 drivers/pci/msi.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 5d70f49..0771508 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -511,7 +511,6 @@ static void msi_kobj_release(struct kobject *kobj)
 {
 	struct msi_desc *entry = to_msi_desc(kobj);
 
-	pci_dev_put(entry->dev);
 	kfree(entry);
 }
 
@@ -534,13 +533,10 @@ static int populate_msi_sysfs(struct pci_dev *pdev)
 	list_for_each_entry(entry, &pdev->msi_list, list) {
 		kobj = &entry->kobj;
 		kobj->kset = pdev->msi_kset;
-		pci_dev_get(pdev);
 		ret = kobject_init_and_add(kobj, &msi_irq_ktype, NULL,
 				     "%u", entry->irq);
-		if (ret) {
-			pci_dev_put(pdev);
+		if (ret)
 			return ret;
-		}
 	}
 
 	return 0;
-- 
1.8.4

[PATCH v2 2/3] msi: always unregister ->msi_kset within free_msi_irqs()

[Veaceslav Falico]

Currently we create and populate ->msi_kset while allocating irqs in
populate_msi_sysfs(), however if it fails and/or we want to free the
entries - we don't always remove it, and we might have problems if we've
failed to allocate irqs and try it again.

To fix that, move the unregister part to free_msi_irqs() and remove already
existing ones. Also, verify if it was actually created - we don't always
call free_msi_irqs() after populate_msi_sysfs().

CC: Bjorn Helgaas <bhelgaas@google.com>
CC: Neil Horman <nhorman@tuxdriver.com>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC: linux-pci@vger.kernel.org
CC: linux-kernel@vger.kernel.org
Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
---

Notes:
    v1  -> v2:
    Verify if the kset was actually register before unregistering.

 drivers/pci/msi.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 0771508..dafda2b 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -391,6 +391,11 @@ static void free_msi_irqs(struct pci_dev *dev)
 			kfree(entry);
 		}
 	}
+
+	if (dev->msi_kset) {
+		kset_unregister(dev->msi_kset);
+		dev->msi_kset = NULL;
+	}
 }
 
 static struct msi_desc *alloc_msi_entry(struct pci_dev *dev)
@@ -904,8 +909,6 @@ void pci_disable_msi(struct pci_dev *dev)
 
 	pci_msi_shutdown(dev);
 	free_msi_irqs(dev);
-	kset_unregister(dev->msi_kset);
-	dev->msi_kset = NULL;
 }
 EXPORT_SYMBOL(pci_disable_msi);
 
@@ -1002,8 +1005,6 @@ void pci_disable_msix(struct pci_dev *dev)
 
 	pci_msix_shutdown(dev);
 	free_msi_irqs(dev);
-	kset_unregister(dev->msi_kset);
-	dev->msi_kset = NULL;
 }
 EXPORT_SYMBOL(pci_disable_msix);
 
-- 
1.8.4

Re: [PATCH v2 2/3] msi: always unregister ->msi_kset within free_msi_irqs()

[Neil Horman]

On Thu, Sep 26, 2013 at 04:11:14PM +0200, Veaceslav Falico wrote:
> Currently we create and populate ->msi_kset while allocating irqs in
> populate_msi_sysfs(), however if it fails and/or we want to free the
> entries - we don't always remove it, and we might have problems if we've
> failed to allocate irqs and try it again.
> 
> To fix that, move the unregister part to free_msi_irqs() and remove already
> existing ones. Also, verify if it was actually created - we don't always
> call free_msi_irqs() after populate_msi_sysfs().
> 
> CC: Bjorn Helgaas <bhelgaas@google.com>
> CC: Neil Horman <nhorman@tuxdriver.com>
> CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> CC: linux-pci@vger.kernel.org
> CC: linux-kernel@vger.kernel.org
> Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>

[PATCH v2 3/3] msi: remove useless kobject_del() in free_msi_irqs()

[Veaceslav Falico]

We only need to kobject_put() on removal (which will, eventually, call
kobject_del()). kobject_del() should be implicitly used only on circular
references (per documentation), however it's not the case here.

CC: Bjorn Helgaas <bhelgaas@google.com>
CC: Neil Horman <nhorman@tuxdriver.com>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC: linux-pci@vger.kernel.org
CC: linux-kernel@vger.kernel.org
Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
---
 drivers/pci/msi.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index dafda2b..d62c468 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -384,12 +384,10 @@ static void free_msi_irqs(struct pci_dev *dev)
 		 * kobject->release will take care of freeing the entry via
 		 * msi_kobj_release().
 		 */
-		if (entry->kobj.parent) {
-			kobject_del(&entry->kobj);
+		if (entry->kobj.parent)
 			kobject_put(&entry->kobj);
-		} else {
+		else
 			kfree(entry);
-		}
 	}
 
 	if (dev->msi_kset) {
-- 
1.8.4

Re: [PATCH v2 1/3] pci: remove redundant pci_dev_get/put() on kobject (un)register

[Neil Horman]

On Thu, Sep 26, 2013 at 04:11:13PM +0200, Veaceslav Falico wrote:
> Currently we're pci_dev_get/put()-ing pci device on every kobject
> creation/removal. It's useless per se - the kobject is part of the device
> itself, so it should be removed when there are no users of the pdev, and is
> not a user of it.
> 
> CC: Bjorn Helgaas <bhelgaas@google.com>
> CC: Neil Horman <nhorman@tuxdriver.com>
> CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> CC: linux-pci@vger.kernel.org
> CC: linux-kernel@vger.kernel.org
> Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>