Messages in this thread Patch in this message | | | Date | Sun, 05 Jul 2015 17:12:35 -0000 | From | Thomas Gleixner <> | Subject | [patch 4/4] x86/irq: Retrieve irq data after locking irq_desc |
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irq_data is protected by irq_desc->lock, so retrieving the irq chip from irq_data outside the lock is racy vs. an concurrent update. Move it into the lock held region.
While at it add a comment why the vector walk does not require vector_lock.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de> --- arch/x86/kernel/irq.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
Index: tip/arch/x86/kernel/irq.c =================================================================== --- tip.orig/arch/x86/kernel/irq.c +++ tip/arch/x86/kernel/irq.c @@ -497,6 +497,11 @@ void fixup_irqs(void) */ mdelay(1); + /* + * We can walk the vector array of this cpu without holding + * vector_lock because the cpu is already marked !online, so + * nothing else will touch it. + */ for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS; vector++) { unsigned int irr; @@ -508,9 +513,9 @@ void fixup_irqs(void) irq = __this_cpu_read(vector_irq[vector]); desc = irq_to_desc(irq); + raw_spin_lock(&desc->lock); data = irq_desc_get_irq_data(desc); chip = irq_data_get_irq_chip(data); - raw_spin_lock(&desc->lock); if (chip->irq_retrigger) { chip->irq_retrigger(data); __this_cpu_write(vector_irq[vector], VECTOR_RETRIGGERED);
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