This patch fixes a kernel bug which is triggered when using the
irqbalance daemon with MSI-X hardware.
Because both MSI-X interrupt messages and MSI-X table writes are posted,
it's possible for them to cross while in-flight. This results in
interrupts being received long after the kernel thinks they're disabled,
and in interrupts being sent to stale vectors after rebalancing.
This patch performs a read flush after writes to the MSI-X table for
mask/unmask and rebalancing operations.
This patch has been validated with (unreleased) network hardware which
uses MSI-X.
Revised with input from Eric Biederman.
Signed-off-by: Mitch Williams <[EMAIL PROTECTED]>
diff -urpN -X dontdiff linux-2.6.21-rc5-clean/arch/i386/kernel/io_apic.c
linux-2.6.21-rc5/arch/i386/kernel/io_apic.c
--- linux-2.6.21-rc5-clean/arch/i386/kernel/io_apic.c 2007-03-28
10:05:22.000000000 -0700
+++ linux-2.6.21-rc5/arch/i386/kernel/io_apic.c 2007-03-28 10:19:14.000000000
-0700
@@ -2584,6 +2584,7 @@ static void set_msi_irq_affinity(unsigne
msg.address_lo |= MSI_ADDR_DEST_ID(dest);
write_msi_msg(irq, &msg);
+ msix_flush_writes(irq);
irq_desc[irq].affinity = mask;
}
#endif /* CONFIG_SMP */
diff -urpN -X dontdiff linux-2.6.21-rc5-clean/arch/ia64/kernel/msi_ia64.c
linux-2.6.21-rc5/arch/ia64/kernel/msi_ia64.c
--- linux-2.6.21-rc5-clean/arch/ia64/kernel/msi_ia64.c 2007-03-28
10:05:22.000000000 -0700
+++ linux-2.6.21-rc5/arch/ia64/kernel/msi_ia64.c 2007-03-28
09:34:27.000000000 -0700
@@ -60,6 +60,7 @@ static void ia64_set_msi_irq_affinity(un
msg.address_lo = addr;
write_msi_msg(irq, &msg);
+ msix_flush_writes(irq);
irq_desc[irq].affinity = cpu_mask;
}
#endif /* CONFIG_SMP */
diff -urpN -X dontdiff linux-2.6.21-rc5-clean/arch/ia64/sn/kernel/msi_sn.c
linux-2.6.21-rc5/arch/ia64/sn/kernel/msi_sn.c
--- linux-2.6.21-rc5-clean/arch/ia64/sn/kernel/msi_sn.c 2007-03-28
10:05:22.000000000 -0700
+++ linux-2.6.21-rc5/arch/ia64/sn/kernel/msi_sn.c 2007-03-28
09:34:06.000000000 -0700
@@ -204,6 +204,7 @@ static void sn_set_msi_irq_affinity(unsi
msg.address_lo = (u32)(bus_addr & 0x00000000ffffffff);
write_msi_msg(irq, &msg);
+ msix_flush_writes(irq);
irq_desc[irq].affinity = cpu_mask;
}
#endif /* CONFIG_SMP */
diff -urpN -X dontdiff linux-2.6.21-rc5-clean/arch/x86_64/kernel/io_apic.c
linux-2.6.21-rc5/arch/x86_64/kernel/io_apic.c
--- linux-2.6.21-rc5-clean/arch/x86_64/kernel/io_apic.c 2007-03-28
10:05:22.000000000 -0700
+++ linux-2.6.21-rc5/arch/x86_64/kernel/io_apic.c 2007-03-28
10:18:52.000000000 -0700
@@ -1956,6 +1956,7 @@ static void set_msi_irq_affinity(unsigne
msg.address_lo |= MSI_ADDR_DEST_ID(dest);
write_msi_msg(irq, &msg);
+ msix_flush_writes(irq);
irq_desc[irq].affinity = mask;
}
#endif /* CONFIG_SMP */
diff -urpN -X dontdiff linux-2.6.21-rc5-clean/drivers/pci/msi.c
linux-2.6.21-rc5/drivers/pci/msi.c
--- linux-2.6.21-rc5-clean/drivers/pci/msi.c 2007-03-28 10:05:24.000000000
-0700
+++ linux-2.6.21-rc5/drivers/pci/msi.c 2007-03-28 09:21:34.000000000 -0700
@@ -68,6 +68,29 @@ static void msix_set_enable(struct pci_d
}
}
+void msix_flush_writes(unsigned int irq)
+{
+ struct msi_desc *entry;
+
+ entry = get_irq_msi(irq);
+ BUG_ON(!entry || !entry->dev);
+ switch (entry->msi_attrib.type) {
+ case PCI_CAP_ID_MSI:
+ /* nothing to do */
+ break;
+ case PCI_CAP_ID_MSIX:
+ {
+ int offset = entry->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE +
+ PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET;
+ readl(entry->mask_base + offset);
+ break;
+ }
+ default:
+ BUG();
+ break;
+ }
+}
+
static void msi_set_mask_bit(unsigned int irq, int flag)
{
struct msi_desc *entry;
@@ -186,11 +209,13 @@ void write_msi_msg(unsigned int irq, str
void mask_msi_irq(unsigned int irq)
{
msi_set_mask_bit(irq, 1);
+ msix_flush_writes(irq);
}
void unmask_msi_irq(unsigned int irq)
{
msi_set_mask_bit(irq, 0);
+ msix_flush_writes(irq);
}
static int msi_free_irq(struct pci_dev* dev, int irq);
diff -urpN -X dontdiff linux-2.6.21-rc5-clean/include/linux/msi.h
linux-2.6.21-rc5/include/linux/msi.h
--- linux-2.6.21-rc5-clean/include/linux/msi.h 2007-03-28 10:05:25.000000000
-0700
+++ linux-2.6.21-rc5/include/linux/msi.h 2007-03-28 09:21:51.000000000
-0700
@@ -12,6 +12,7 @@ extern void mask_msi_irq(unsigned int ir
extern void unmask_msi_irq(unsigned int irq);
extern void read_msi_msg(unsigned int irq, struct msi_msg *msg);
extern void write_msi_msg(unsigned int irq, struct msi_msg *msg);
+extern void msix_flush_writes(unsigned int irq);
struct msi_desc {
struct {
-
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