** Changed in: linux (Ubuntu)
Status: Incomplete => Confirmed
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https://bugs.launchpad.net/bugs/1359514
Title:
pci-xgene-msi: fixed deadlock in irq_set_affinity
Status in “linux” package in Ubuntu:
Confirmed
Bug description:
Issue: CPU affinity is changed while irqbalance is running.
+ Problem explanation:
- Old code
+ Call xgene_msi_cascade function (CPU x)
+ raw_spin_lock(&desc->lock); (CPU x)
+ Goto generic_handle_irq (CPU x)
+ The CPU x doesn't have a chance to exit the xgene_msi_cascade
function to unlock desc->lock before Linux scheduce and call
xgene_msi_set_affinity (irqbalance is caller) in the same CPU x
+ In irq_set_affinity, call raw_spin_lock_irqsave(&desc->lock, flags)
which cause deadlock to CPU x because it disables preempt
- New code
+ Use chained_irq_enter and exit as the standard way to cascade
interrupt functions.
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