When there are a large number of interrupts occurring on the tx
queue(irq smp_affinity=1) of the network card, changing the CPU
affinity of the tx queue (echo 2 > /proc/irq/xx/smp_affinity)
will cause handle_edge_irq to loop for a long time in the
do {} while() loop.
After setting the IRQ CPU affinity, the next interrupt will only
be activated when it arrives. Therefore, the next interrupt will
still be on CPU 0. When a new CPU affinity is activated on CPU 0,
subsequent interrupts will be processed on CPU 1.
cpu 0 cpu 1
- handle_edge_irq
- apic_ack_irq
- irq_do_set_affinity
- handle_edge_irq
- do {
- handle_irq_event
- istate &= ~IRQS_PENDIN
- IRQD_IRQ_INPROGRESS
- spin_unlock()
- spin_lock()
- istate |= IRQS_PENDIN
- handle_irq_event_percpu - mask_ack_irq()
- spin_unlock()
- spin_unlock
} while(IRQS_PENDIN &&
!irq_disable)
Therefore, when determining whether to continue looping, we add a check
to see if the current CPU belongs to the affinity table of the interrupt.
Signed-off-by: Wei Gong <[email protected]>
---
kernel/irq/chip.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index dc94e0bf2c94..cafd395367c3 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -831,7 +831,8 @@ void handle_edge_irq(struct irq_desc *desc)
handle_irq_event(desc);
} while ((desc->istate & IRQS_PENDING) &&
- !irqd_irq_disabled(&desc->irq_data));
+ !irqd_irq_disabled(&desc->irq_data) &&
+ cpumask_test_cpu(smp_processor_id(), desc->irq_common_data.affinity));
out_unlock:
raw_spin_unlock(&desc->lock);
--
2.32.1 (Apple Git-133)
Hi Wei,
kernel test robot noticed the following build errors:
[auto build test ERROR on tip/irq/core]
[also build test ERROR on linus/master v6.6-rc2 next-20230921]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Wei-Gong/genirq-avoid-long-loops-in-handle_edge_irq/20230922-025437
base: tip/irq/core
patch link: https://lore.kernel.org/r/20230921080146.37186-1-gongwei833x%40gmail.com
patch subject: [PATCH] genirq: avoid long loops in handle_edge_irq
config: um-allnoconfig (https://download.01.org/0day-ci/archive/20230923/[email protected]/config)
compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230923/[email protected]/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
All errors (new ones prefixed by >>):
In file included from kernel/irq/chip.c:11:
In file included from include/linux/irq.h:20:
In file included from include/linux/io.h:13:
In file included from arch/um/include/asm/io.h:24:
include/asm-generic/io.h:547:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
547 | val = __raw_readb(PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:560:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
560 | val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
| ~~~~~~~~~~ ^
include/uapi/linux/byteorder/little_endian.h:37:51: note: expanded from macro '__le16_to_cpu'
37 | #define __le16_to_cpu(x) ((__force __u16)(__le16)(x))
| ^
In file included from kernel/irq/chip.c:11:
In file included from include/linux/irq.h:20:
In file included from include/linux/io.h:13:
In file included from arch/um/include/asm/io.h:24:
include/asm-generic/io.h:573:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
573 | val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
| ~~~~~~~~~~ ^
include/uapi/linux/byteorder/little_endian.h:35:51: note: expanded from macro '__le32_to_cpu'
35 | #define __le32_to_cpu(x) ((__force __u32)(__le32)(x))
| ^
In file included from kernel/irq/chip.c:11:
In file included from include/linux/irq.h:20:
In file included from include/linux/io.h:13:
In file included from arch/um/include/asm/io.h:24:
include/asm-generic/io.h:584:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
584 | __raw_writeb(value, PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:594:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
594 | __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:604:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
604 | __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:692:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
692 | readsb(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:700:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
700 | readsw(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:708:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
708 | readsl(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:717:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
717 | writesb(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:726:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
726 | writesw(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:735:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
735 | writesl(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
>> kernel/irq/chip.c:835:63: error: no member named 'affinity' in 'struct irq_common_data'
835 | cpumask_test_cpu(smp_processor_id(), desc->irq_common_data.affinity));
| ~~~~~~~~~~~~~~~~~~~~~ ^
12 warnings and 1 error generated.
vim +835 kernel/irq/chip.c
771
772 /**
773 * handle_edge_irq - edge type IRQ handler
774 * @desc: the interrupt description structure for this irq
775 *
776 * Interrupt occurs on the falling and/or rising edge of a hardware
777 * signal. The occurrence is latched into the irq controller hardware
778 * and must be acked in order to be reenabled. After the ack another
779 * interrupt can happen on the same source even before the first one
780 * is handled by the associated event handler. If this happens it
781 * might be necessary to disable (mask) the interrupt depending on the
782 * controller hardware. This requires to reenable the interrupt inside
783 * of the loop which handles the interrupts which have arrived while
784 * the handler was running. If all pending interrupts are handled, the
785 * loop is left.
786 */
787 void handle_edge_irq(struct irq_desc *desc)
788 {
789 raw_spin_lock(&desc->lock);
790
791 desc->istate &= ~(IRQS_REPLAY | IRQS_WAITING);
792
793 if (!irq_may_run(desc)) {
794 desc->istate |= IRQS_PENDING;
795 mask_ack_irq(desc);
796 goto out_unlock;
797 }
798
799 /*
800 * If its disabled or no action available then mask it and get
801 * out of here.
802 */
803 if (irqd_irq_disabled(&desc->irq_data) || !desc->action) {
804 desc->istate |= IRQS_PENDING;
805 mask_ack_irq(desc);
806 goto out_unlock;
807 }
808
809 kstat_incr_irqs_this_cpu(desc);
810
811 /* Start handling the irq */
812 desc->irq_data.chip->irq_ack(&desc->irq_data);
813
814 do {
815 if (unlikely(!desc->action)) {
816 mask_irq(desc);
817 goto out_unlock;
818 }
819
820 /*
821 * When another irq arrived while we were handling
822 * one, we could have masked the irq.
823 * Reenable it, if it was not disabled in meantime.
824 */
825 if (unlikely(desc->istate & IRQS_PENDING)) {
826 if (!irqd_irq_disabled(&desc->irq_data) &&
827 irqd_irq_masked(&desc->irq_data))
828 unmask_irq(desc);
829 }
830
831 handle_irq_event(desc);
832
833 } while ((desc->istate & IRQS_PENDING) &&
834 !irqd_irq_disabled(&desc->irq_data) &&
> 835 cpumask_test_cpu(smp_processor_id(), desc->irq_common_data.affinity));
836
837 out_unlock:
838 raw_spin_unlock(&desc->lock);
839 }
840 EXPORT_SYMBOL(handle_edge_irq);
841
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki