x86/irq: Protect smp_cleanup_move

smp_cleanup_move fiddles without protection in the interrupt
descriptors and the vector array. A concurrent irq setup/teardown or
affinity setting can pull the rug under that operation.

Add proper locking.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Link: http://lkml.kernel.org/r/20150802203609.222975294@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index f47069e8efacde3da4d1cf5e30a15379166957c8..63d58b08a109ad1a92a5327fff0da721fb91efc3 100644 (file)
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -539,6 +539,9 @@ asmlinkage __visible void smp_irq_move_cleanup_interrupt(void)
 
        entering_ack_irq();
 
+       /* Prevent vectors vanishing under us */
+       raw_spin_lock(&vector_lock);
+
        me = smp_processor_id();
        for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) {
                int irq;
@@ -546,6 +549,7 @@ asmlinkage __visible void smp_irq_move_cleanup_interrupt(void)
                struct irq_desc *desc;
                struct apic_chip_data *data;
 
+       retry:
                irq = __this_cpu_read(vector_irq[vector]);
 
                if (irq <= VECTOR_UNDEFINED)
@@ -555,12 +559,16 @@ asmlinkage __visible void smp_irq_move_cleanup_interrupt(void)
                if (!desc)
                        continue;
 
+               if (!raw_spin_trylock(&desc->lock)) {
+                       raw_spin_unlock(&vector_lock);
+                       cpu_relax();
+                       raw_spin_lock(&vector_lock);
+                       goto retry;
+               }
+
                data = apic_chip_data(&desc->irq_data);
                if (!data)
-                       continue;
-
-               raw_spin_lock(&desc->lock);
-
+                       goto unlock;
                /*
                 * Check if the irq migration is in progress. If so, we
                 * haven't received the cleanup request yet for this irq.
@@ -589,6 +597,8 @@ unlock:
                raw_spin_unlock(&desc->lock);
        }
 
+       raw_spin_unlock(&vector_lock);
+
        exiting_irq();
 }