On Wed, Sep 25, 2013 at 03:34:58PM -0600, Bjorn Helgaas wrote:
On Mon, Sep 16, 2013 at 7:47 PM, Veaceslav Falico <vfalico@xxxxxxxxxx> wrote:
Currently, we first do kobject_put(&entry->kobj) and the kfree(entry),
however kobject_put() doesn't guarantee us that it was the last reference
and that the kobj isn't used currently by someone else, so after we
kfree(entry) with the struct kobject - other users will begin using the
freed memory, instead of the actual kobject.
Fix this by using the kobject->release callback, which is called last when
the kobject is indeed not used and is cleaned up - it's msi_kobj_release(),
which can do the kfree(entry) safely (kobject_put/cleanup doesn't use the
kobj itself after ->release() was called, so we're safe).
In case we've failed to create the sysfs directories - just kfree()
it - cause we don't have the kobjects attached.
Also, remove the same functionality from populate_msi_sysfs(), cause on
failure we anyway call free_msi_irqs(), which will take care of all the
kobjects properly.
I agree; it looks like populate_msi_sysfs() doesn't need to have the
cleanup in it. Can you split that into a separate patch, since I
don't think it depends on the kfree() fix?
Yep, will do and re-send in two patchsets.
Thank you!
Bjorn
CC: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
CC: linux-pci@xxxxxxxxxxxxxxx
CC: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Veaceslav Falico <vfalico@xxxxxxxxxx>
---
drivers/pci/msi.c | 27 +++++++++------------------
1 file changed, 9 insertions(+), 18 deletions(-)
diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 68da921..c9236e4 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -374,19 +374,22 @@ static void free_msi_irqs(struct pci_dev *dev)
iounmap(entry->mask_base);
}
+ list_del(&entry->list);
+
/*
* Its possible that we get into this path
* When populate_msi_sysfs fails, which means the entries
* were not registered with sysfs. In that case don't
- * unregister them.
+ * unregister them, and just free. Otherwise the
+ * kobject->release will take care of freeing the entry via
+ * msi_kobj_release().
*/
if (entry->kobj.parent) {
kobject_del(&entry->kobj);
kobject_put(&entry->kobj);
+ } else {
+ kfree(entry);
}
-
- list_del(&entry->list);
- kfree(entry);
}
kset_unregister(dev->msi_kset);
@@ -512,6 +515,7 @@ static void msi_kobj_release(struct kobject *kobj)
struct msi_desc *entry = to_msi_desc(kobj);
pci_dev_put(entry->dev);
+ kfree(entry);
}
static struct kobj_type msi_irq_ktype = {
@@ -525,7 +529,6 @@ static int populate_msi_sysfs(struct pci_dev *pdev)
struct msi_desc *entry;
struct kobject *kobj;
int ret;
- int count = 0;
pdev->msi_kset = kset_create_and_add("msi_irqs", NULL, &pdev->dev.kobj);
if (!pdev->msi_kset)
@@ -539,23 +542,11 @@ static int populate_msi_sysfs(struct pci_dev *pdev)
"%u", entry->irq);
if (ret) {
pci_dev_put(pdev);
- goto out_unroll;
+ return ret;
}
-
- count++;
}
return 0;
-
-out_unroll:
- list_for_each_entry(entry, &pdev->msi_list, list) {
- if (!count)
- break;
- kobject_del(&entry->kobj);
- kobject_put(&entry->kobj);
- count--;
- }
- return ret;
}
/**
--
1.8.4
--
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