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Prarit Bhargava authored
Several patches to fix cpu hotplug and the down'd cpu's irq relocations have been submitted in the past month or so. The patches should resolve the problems with cpu hotplug and irq relocation, however, there is always a possibility that a bug still exists. The big problem with debugging these irq reassignments is that the cpu down completes and then we get random stack traces from drivers for which irqs have not been properly assigned to a new cpu. The stack traces are a mix of storage, network, and other kernel subsystem (I once saw the serial port stop working ...) warnings and failures. The problem with these failures is that they are difficult to diagnose. There is no warning in the cpu hotplug down path to indicate that an IRQ has failed to be assigned to a new cpu, and all we are left with is a stack trace from a driver, or a non-functional device. If we had some information on the console debugging these situations would be much easier; after all we can map an IRQ to a device by simply using lspci or /proc/interrupts. The current code, fixup_irqs(), which migrates IRQs from the down'd cpu and is called close to the end of the cpu down path, calls chip->set_irq_affinity which eventually calls __assign_irq_vector(). Errors are not propogated back from this function call and this results in silent irq relocation failures. This patch fixes this issue by returning the error codes up the call stack and prints out a warning if there is a relocation failure. Signed-off-by:
Prarit Bhargava <prarit@redhat.com> Acked-by:
Thomas Gleixner <tglx@linutronix.de> Cc: Rui Wang <rui.y.wang@intel.com> Cc: Liu Ping Fan <kernelfans@gmail.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com> Cc: Lv Zheng <lv.zheng@intel.com> Cc: Seiji Aguchi <seiji.aguchi@hds.com> Cc: Yang Zhang <yang.z.zhang@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Steven Rostedt (Red Hat) <rostedt@goodmis.org> Cc: Li Fei <fei.li@intel.com> Cc: gong.chen@linux.intel.com Link: http://lkml.kernel.org/r/1396440673-18286-1-git-send-email-prarit@redhat.com [ Made small cleanliness tweaks. ] Signed-off-by:
Ingo Molnar <mingo@kernel.org>
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