arm-cc*: fix PMU interrupt flags
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| Patch | Will Deacon |
|---|---|
| Series | R-b |
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Cover letter [PATCHv2 0/2] arm-cc*: fix PMU interrupt flags
Quoted 9 lines · Mark Rutland
As discovered during review of the X-Gene SoC PMU [1], the arm-cc{i,n} drivers don't ensure that IRQ balancers don't migrate interrupts.
This is problematic for the perf core code, which requires mutual exclusion of certain operations (e.g. event rotation, cross-calls, and irq handling) to be provided by disabling IRQs, which only works if all operations occur on the same CPU. This is also required for safe (lockless) manipulation of some data structures.
Quoted 7 lines
To avoid this problem, we must request interrupts with
IRQF_NOBALANCING, as is already the case for CPU PMU drivers which make use of interrupts.To ensure synchronisation between IRQ handlers and other manipulation of said data structures or HW state, we must also ensure that the interrupt handlers are not threaded, by requesting them with
IRQF_NO_THREAD, as is already the case for CPU PMU drivers.
Thanks, looks good now:
Will