genirq: keep affinities set from userspace across free/request_irq()

Impact: preserve user-modified affinities on interrupts

Kumar Galak noticed that commit
18404756765c713a0be4eb1082920c04822ce588 (genirq: Expose default irq
affinity mask (take 3))

overrides an already set affinity setting across a free /
request_irq(). Happens e.g. with ifdown/ifup of a network device.

Change the logic to mark the affinities as set and keep them
intact. This also fixes the unlocked access to irq_desc in
irq_select_affinity() when called from irq_affinity_proc_write()

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 6 deletions

diff --git a/include/linux/irq.h b/include/linux/irq.h
index d058c57be02d..36b186eb318b 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -63,7 +63,8 @@ typedef	void (*irq_flow_handler_t)(unsigned int irq,
 #define IRQ_MOVE_PENDING        0x00200000      /* need to re-target IRQ destination */
 #define IRQ_NO_BALANCING        0x00400000      /* IRQ is excluded from balancing */
 #define IRQ_SPURIOUS_DISABLED   0x00800000      /* IRQ was disabled by the spurious trap */
-#define IRQ_MOVE_PCNTXT 0x01000000      /* IRQ migration from process context */
+#define IRQ_MOVE_PCNTXT         0x01000000      /* IRQ migration from process context */
+#define IRQ_AFFINITY_SET        0x02000000      /* IRQ affinity was set from userspace*/
 
 #ifdef CONFIG_IRQ_PER_CPU
 # define CHECK_IRQ_PER_CPU(var) ((var) & IRQ_PER_CPU)
@@ -210,7 +211,6 @@ extern int setup_irq(unsigned int irq, struct irqaction *new);
 
 #ifdef CONFIG_GENERIC_PENDING_IRQ
 
-void set_pending_irq(unsigned int irq, cpumask_t mask);
 void move_native_irq(int irq);
 void move_masked_irq(int irq);
 
@@ -228,10 +228,6 @@ static inline void move_masked_irq(int irq)
 {
 }
 
-static inline void set_pending_irq(unsigned int irq, cpumask_t mask)
-{
-}
-
 #endif /* CONFIG_GENERIC_PENDING_IRQ */
 
 #else /* CONFIG_SMP */