[patch 2/3] x86/apic/vector: Handle vector release on CPU unplug correctly

[Thomas Gleixner]

When a irq vector is replaced, then the previous vector is normally
released when the first interrupt happens on the new vector. If the target
CPU of the previous vector is already offline when the new vector is
installed, then the previous vector is silently discarded, which leads to
accounting issues causing suspend failures and other problems.

Adjust the logic so that the previous vector is freed in the underlying
matrix allocator to ensure that the accounting stays correct.

Fixes: 69cde0004a4b ("x86/vector: Use matrix allocator for vector assignment")
Reported-by: Yuriy Vostrikov <delamonpansie@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Tested-by: Yuriy Vostrikov <delamonpansie@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
 arch/x86/kernel/apic/vector.c |   22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -134,21 +134,39 @@ static void apic_update_vector(struct ir
 {
 	struct apic_chip_data *apicd = apic_chip_data(irqd);
 	struct irq_desc *desc = irq_data_to_desc(irqd);
+	bool managed = irqd_affinity_is_managed(irqd);
 
 	lockdep_assert_held(&vector_lock);
 
 	trace_vector_update(irqd->irq, newvec, newcpu, apicd->vector,
 			    apicd->cpu);
 
-	/* Setup the vector move, if required  */
-	if (apicd->vector && cpu_online(apicd->cpu)) {
+	/*
+	 * If there is no vector associated or if the associated vector is
+	 * the shutdown vector, which is associated to make PCI/MSI
+	 * shutdown mode work, then there is nothing to release.
+	 */
+	if (!apic->vector || apicd->vector == MANAGED_IRQ_SHUTDOWN_VECTOR)
+		goto setnew;
+	/*
+	 * If the target CPU of the previous vector is online, then mark
+	 * the vector as move in progress and store it for cleanup when the
+	 * first interrupt on the new vector arrives. If the target CPU is
+	 * offline then the regular release mechanism via the cleanup
+	 * vector is not possible and the vector can be immediately freed
+	 * in the underlying matrix allocator.
+	 */
+	if (cpu_online(apicd->cpu)) {
 		apicd->move_in_progress = true;
 		apicd->prev_vector = apicd->vector;
 		apicd->prev_cpu = apicd->cpu;
 	} else {
+		irq_matrix_free(vector_matrix, apicd->cpu, apicd->vector,
+				managed);
 		apicd->prev_vector = 0;
 	}
 
+setnew:
 	apicd->vector = newvec;
 	apicd->cpu = newcpu;
 	BUG_ON(!IS_ERR_OR_NULL(per_cpu(vector_irq, newcpu)[newvec]));