Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull irq core fix from Thomas Gleixner: "A single fix plugging a long standing race between proc/stat and proc/interrupts access and freeing of interrupt descriptors" * 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: genirq: Prevent proc race against freeing of irq descriptors
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ac88ee3b6c
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@ -159,7 +159,7 @@ static int show_stat(struct seq_file *p, void *v)
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/* sum again ? it could be updated? */
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for_each_irq_nr(j)
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seq_put_decimal_ull(p, ' ', kstat_irqs(j));
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seq_put_decimal_ull(p, ' ', kstat_irqs_usr(j));
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seq_printf(p,
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"\nctxt %llu\n"
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@ -68,6 +68,7 @@ static inline unsigned int kstat_softirqs_cpu(unsigned int irq, int cpu)
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* Number of interrupts per specific IRQ source, since bootup
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*/
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extern unsigned int kstat_irqs(unsigned int irq);
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extern unsigned int kstat_irqs_usr(unsigned int irq);
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/*
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* Number of interrupts per cpu, since bootup
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@ -78,8 +78,12 @@ extern void unmask_threaded_irq(struct irq_desc *desc);
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#ifdef CONFIG_SPARSE_IRQ
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static inline void irq_mark_irq(unsigned int irq) { }
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extern void irq_lock_sparse(void);
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extern void irq_unlock_sparse(void);
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#else
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extern void irq_mark_irq(unsigned int irq);
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static inline void irq_lock_sparse(void) { }
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static inline void irq_unlock_sparse(void) { }
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#endif
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extern void init_kstat_irqs(struct irq_desc *desc, int node, int nr);
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@ -132,6 +132,16 @@ static void free_masks(struct irq_desc *desc)
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static inline void free_masks(struct irq_desc *desc) { }
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#endif
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void irq_lock_sparse(void)
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{
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mutex_lock(&sparse_irq_lock);
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}
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void irq_unlock_sparse(void)
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{
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mutex_unlock(&sparse_irq_lock);
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}
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static struct irq_desc *alloc_desc(int irq, int node, struct module *owner)
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{
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struct irq_desc *desc;
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@ -168,6 +178,12 @@ static void free_desc(unsigned int irq)
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unregister_irq_proc(irq, desc);
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/*
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* sparse_irq_lock protects also show_interrupts() and
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* kstat_irq_usr(). Once we deleted the descriptor from the
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* sparse tree we can free it. Access in proc will fail to
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* lookup the descriptor.
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*/
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mutex_lock(&sparse_irq_lock);
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delete_irq_desc(irq);
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mutex_unlock(&sparse_irq_lock);
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@ -574,6 +590,15 @@ void kstat_incr_irq_this_cpu(unsigned int irq)
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kstat_incr_irqs_this_cpu(irq, irq_to_desc(irq));
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}
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/**
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* kstat_irqs_cpu - Get the statistics for an interrupt on a cpu
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* @irq: The interrupt number
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* @cpu: The cpu number
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*
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* Returns the sum of interrupt counts on @cpu since boot for
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* @irq. The caller must ensure that the interrupt is not removed
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* concurrently.
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*/
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unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
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{
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struct irq_desc *desc = irq_to_desc(irq);
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@ -582,6 +607,14 @@ unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
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*per_cpu_ptr(desc->kstat_irqs, cpu) : 0;
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}
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/**
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* kstat_irqs - Get the statistics for an interrupt
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* @irq: The interrupt number
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*
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* Returns the sum of interrupt counts on all cpus since boot for
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* @irq. The caller must ensure that the interrupt is not removed
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* concurrently.
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*/
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unsigned int kstat_irqs(unsigned int irq)
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{
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struct irq_desc *desc = irq_to_desc(irq);
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@ -594,3 +627,22 @@ unsigned int kstat_irqs(unsigned int irq)
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sum += *per_cpu_ptr(desc->kstat_irqs, cpu);
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return sum;
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}
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/**
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* kstat_irqs_usr - Get the statistics for an interrupt
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* @irq: The interrupt number
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*
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* Returns the sum of interrupt counts on all cpus since boot for
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* @irq. Contrary to kstat_irqs() this can be called from any
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* preemptible context. It's protected against concurrent removal of
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* an interrupt descriptor when sparse irqs are enabled.
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*/
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unsigned int kstat_irqs_usr(unsigned int irq)
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{
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int sum;
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irq_lock_sparse();
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sum = kstat_irqs(irq);
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irq_unlock_sparse();
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return sum;
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}
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@ -15,6 +15,23 @@
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#include "internals.h"
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/*
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* Access rules:
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*
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* procfs protects read/write of /proc/irq/N/ files against a
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* concurrent free of the interrupt descriptor. remove_proc_entry()
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* immediately prevents new read/writes to happen and waits for
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* already running read/write functions to complete.
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*
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* We remove the proc entries first and then delete the interrupt
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* descriptor from the radix tree and free it. So it is guaranteed
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* that irq_to_desc(N) is valid as long as the read/writes are
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* permitted by procfs.
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*
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* The read from /proc/interrupts is a different problem because there
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* is no protection. So the lookup and the access to irqdesc
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* information must be protected by sparse_irq_lock.
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*/
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static struct proc_dir_entry *root_irq_dir;
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#ifdef CONFIG_SMP
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@ -437,9 +454,10 @@ int show_interrupts(struct seq_file *p, void *v)
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seq_putc(p, '\n');
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}
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irq_lock_sparse();
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desc = irq_to_desc(i);
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if (!desc)
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return 0;
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goto outsparse;
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raw_spin_lock_irqsave(&desc->lock, flags);
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for_each_online_cpu(j)
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@ -479,6 +497,8 @@ int show_interrupts(struct seq_file *p, void *v)
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seq_putc(p, '\n');
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out:
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raw_spin_unlock_irqrestore(&desc->lock, flags);
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outsparse:
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irq_unlock_sparse();
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return 0;
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}
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#endif
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