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>

diff --git a/include/linux/irq.h b/include/linux/irq.h
index d058c57be02d3508e27382e63980bfb593658649..36b186eb318bd610aeb7dffcbe7a49f43eba0a7f 100644 (file)
--- 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 */

diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index c9767e641980e1b2ae91454fe723088ad9cc5f83..64c1c7253dae091b931652aa235ba3c44b6060c5 100644 (file)
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -25,6 +25,8 @@ static inline void unregister_handler_proc(unsigned int irq,
                                           struct irqaction *action) { }
 #endif
 
+extern int irq_select_affinity_usr(unsigned int irq);
+
 /*
  * Debugging printout:
  */

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index c498a1b8c621e02894974b7f0e0cda8e96d81011..634a2a9551045d297bc5be22aacd50e6e2b713c6 100644 (file)
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -82,24 +82,27 @@ int irq_can_set_affinity(unsigned int irq)
 int irq_set_affinity(unsigned int irq, cpumask_t cpumask)
 {
        struct irq_desc *desc = irq_to_desc(irq);
+       unsigned long flags;
 
        if (!desc->chip->set_affinity)
                return -EINVAL;
 
+       spin_lock_irqsave(&desc->lock, flags);
+
 #ifdef CONFIG_GENERIC_PENDING_IRQ
        if (desc->status & IRQ_MOVE_PCNTXT || desc->status & IRQ_DISABLED) {
-               unsigned long flags;
-
-               spin_lock_irqsave(&desc->lock, flags);
                desc->affinity = cpumask;
                desc->chip->set_affinity(irq, cpumask);
-               spin_unlock_irqrestore(&desc->lock, flags);
-       } else
-               set_pending_irq(irq, cpumask);
+       } else {
+               desc->status |= IRQ_MOVE_PENDING;
+               desc->pending_mask = cpumask;
+       }
 #else
        desc->affinity = cpumask;
        desc->chip->set_affinity(irq, cpumask);
 #endif
+       desc->status |= IRQ_AFFINITY_SET;
+       spin_unlock_irqrestore(&desc->lock, flags);
        return 0;
 }
 
@@ -107,24 +110,59 @@ int irq_set_affinity(unsigned int irq, cpumask_t cpumask)
 /*
  * Generic version of the affinity autoselector.
  */
-int irq_select_affinity(unsigned int irq)
+int do_irq_select_affinity(unsigned int irq, struct irq_desc *desc)
 {
        cpumask_t mask;
-       struct irq_desc *desc;
 
        if (!irq_can_set_affinity(irq))
                return 0;
 
        cpus_and(mask, cpu_online_map, irq_default_affinity);
 
-       desc = irq_to_desc(irq);
+       /*
+        * Preserve an userspace affinity setup, but make sure that
+        * one of the targets is online.
+        */
+       if (desc->status & IRQ_AFFINITY_SET) {
+               if (cpus_intersects(desc->affinity, cpu_online_map))
+                       mask = desc->affinity;
+               else
+                       desc->status &= ~IRQ_AFFINITY_SET;
+       }
+
        desc->affinity = mask;
        desc->chip->set_affinity(irq, mask);
 
        return 0;
 }
+#else
+static inline int do_irq_select_affinity(unsigned int irq, struct irq_desc *d)
+{
+       return irq_select_affinity(irq);
+}
 #endif
 
+/*
+ * Called when affinity is set via /proc/irq
+ */
+int irq_select_affinity_usr(unsigned int irq)
+{
+       struct irq_desc *desc = irq_to_desc(irq);
+       unsigned long flags;
+       int ret;
+
+       spin_lock_irqsave(&desc->lock, flags);
+       ret = do_irq_select_affinity(irq, desc);
+       spin_unlock_irqrestore(&desc->lock, flags);
+
+       return ret;
+}
+
+#else
+static inline int do_select_irq_affinity(int irq, struct irq_desc *desc)
+{
+       return 0;
+}
 #endif
 
 /**
@@ -446,7 +484,7 @@ __setup_irq(unsigned int irq, struct irq_desc * desc, struct irqaction *new)
                        desc->depth = 1;
 
                /* Set default affinity mask once everything is setup */
-               irq_select_affinity(irq);
+               do_irq_select_affinity(irq, desc);
 
        } else if ((new->flags & IRQF_TRIGGER_MASK)
                        && (new->flags & IRQF_TRIGGER_MASK)

diff --git a/kernel/irq/migration.c b/kernel/irq/migration.c
index 90b920d3f52b3ca29f69cc204ab2481f4d95d4f6..9db681d95814baa2662fdccba0755b09579577cf 100644 (file)
--- a/kernel/irq/migration.c
+++ b/kernel/irq/migration.c
@@ -1,17 +1,6 @@
 
 #include <linux/irq.h>
 
-void set_pending_irq(unsigned int irq, cpumask_t mask)
-{
-       struct irq_desc *desc = irq_to_desc(irq);
-       unsigned long flags;
-
-       spin_lock_irqsave(&desc->lock, flags);
-       desc->status |= IRQ_MOVE_PENDING;
-       desc->pending_mask = mask;
-       spin_unlock_irqrestore(&desc->lock, flags);
-}
-
 void move_masked_irq(int irq)
 {
        struct irq_desc *desc = irq_to_desc(irq);

diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index 4d161c70ba558507dc9be80537a50215052bd52f..d257e7d6a8a4ba4b10504dcd8490c812fe37504c 100644 (file)
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -62,7 +62,7 @@ static ssize_t irq_affinity_proc_write(struct file *file,
        if (!cpus_intersects(new_value, cpu_online_map))
                /* Special case for empty set - allow the architecture
                   code to set default SMP affinity. */
-               return irq_select_affinity(irq) ? -EINVAL : count;
+               return irq_select_affinity_usr(irq) ? -EINVAL : count;
 
        irq_set_affinity(irq, new_value);