platform-msi: Free descriptors in platform_msi_domain_free()

commit 81b1e6e6a8590a19257e37a1633bec098d499c57 upstream.

Since the addition of platform MSI support, there were two helpers
supposed to allocate/free IRQs for a device:

    platform_msi_domain_alloc_irqs()
    platform_msi_domain_free_irqs()

In these helpers, IRQ descriptors are allocated in the "alloc" routine
while they are freed in the "free" one.

Later, two other helpers have been added to handle IRQ domains on top
of MSI domains:

    platform_msi_domain_alloc()
    platform_msi_domain_free()

Seen from the outside, the logic is pretty close with the former
helpers and people used it with the same logic as before: a
platform_msi_domain_alloc() call should be balanced with a
platform_msi_domain_free() call. While this is probably what was
intended to do, the platform_msi_domain_free() does not remove/free
the IRQ descriptor(s) created/inserted in
platform_msi_domain_alloc().

One effect of such situation is that removing a module that requested
an IRQ will let one orphaned IRQ descriptor (with an allocated MSI
entry) in the device descriptors list. Next time the module will be
inserted back, one will observe that the allocation will happen twice
in the MSI domain, one time for the remaining descriptor, one time for
the new one. It also has the side effect to quickly overshoot the
maximum number of allocated MSI and then prevent any module requesting
an interrupt in the same domain to be inserted anymore.

This situation has been met with loops of insertion/removal of the
mvpp2.ko module (requesting 15 MSIs each time).

Fixes: 552c494a7666 ("platform-msi: Allow creation of a MSI-based stacked irq domain")
Cc: stable@vger.kernel.org
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/base/platform-msi.c b/drivers/base/platform-msi.c
index be6a599bc0c1a8da08d0a20f31d7bc054dd1a972..7ba1d731decec65b8a16951f28ea84f371ed64d6 100644 (file)
--- a/drivers/base/platform-msi.c
+++ b/drivers/base/platform-msi.c
@@ -375,14 +375,16 @@ void platform_msi_domain_free(struct irq_domain *domain, unsigned int virq,
                              unsigned int nvec)
 {
        struct platform_msi_priv_data *data = domain->host_data;
-       struct msi_desc *desc;
-       for_each_msi_entry(desc, data->dev) {
+       struct msi_desc *desc, *tmp;
+       for_each_msi_entry_safe(desc, tmp, data->dev) {
                if (WARN_ON(!desc->irq || desc->nvec_used != 1))
                        return;
                if (!(desc->irq >= virq && desc->irq < (virq + nvec)))
                        continue;
 
                irq_domain_free_irqs_common(domain, desc->irq, 1);
+               list_del(&desc->list);
+               free_msi_entry(desc);
        }
 }
 

diff --git a/include/linux/msi.h b/include/linux/msi.h
index 0db320b7bb15d94a07efd185f7266fe6e5a74a7e..debc8aa4ec1978273262ce605156eb850ddc9190 100644 (file)
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -108,6 +108,8 @@ struct msi_desc {
        list_first_entry(dev_to_msi_list((dev)), struct msi_desc, list)
 #define for_each_msi_entry(desc, dev)  \
        list_for_each_entry((desc), dev_to_msi_list((dev)), list)
+#define for_each_msi_entry_safe(desc, tmp, dev)        \
+       list_for_each_entry_safe((desc), (tmp), dev_to_msi_list((dev)), list)
 
 #ifdef CONFIG_PCI_MSI
 #define first_pci_msi_entry(pdev)      first_msi_entry(&(pdev)->dev)