Patch "genirq/matrix: Exclude managed interrupts in irq_matrix_allocated()" has been added to the 5.10-stable tree

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This is a note to let you know that I've just added the patch titled

    genirq/matrix: Exclude managed interrupts in irq_matrix_allocated()

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     genirq-matrix-exclude-managed-interrupts-in-irq_matr.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit c63568c760e8c157dd3b3f215756e4a523e6411b
Author: Chen Yu <yu.c.chen@xxxxxxxxx>
Date:   Fri Oct 20 15:25:22 2023 +0800

    genirq/matrix: Exclude managed interrupts in irq_matrix_allocated()
    
    [ Upstream commit a0b0bad10587ae2948a7c36ca4ffc206007fbcf3 ]
    
    When a CPU is about to be offlined, x86 validates that all active
    interrupts which are targeted to this CPU can be migrated to the remaining
    online CPUs. If not, the offline operation is aborted.
    
    The validation uses irq_matrix_allocated() to retrieve the number of
    vectors which are allocated on the outgoing CPU. The returned number of
    allocated vectors includes also vectors which are associated to managed
    interrupts.
    
    That's overaccounting because managed interrupts are:
    
      - not migrated when the affinity mask of the interrupt targets only
        the outgoing CPU
    
      - migrated to another CPU, but in that case the vector is already
        pre-allocated on the potential target CPUs and must not be taken into
        account.
    
    As a consequence the check whether the remaining online CPUs have enough
    capacity for migrating the allocated vectors from the outgoing CPU might
    fail incorrectly.
    
    Let irq_matrix_allocated() return only the number of allocated non-managed
    interrupts to make this validation check correct.
    
    [ tglx: Amend changelog and fixup kernel-doc comment ]
    
    Fixes: 2f75d9e1c905 ("genirq: Implement bitmap matrix allocator")
    Reported-by: Wendy Wang <wendy.wang@xxxxxxxxx>
    Signed-off-by: Chen Yu <yu.c.chen@xxxxxxxxx>
    Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20231020072522.557846-1-yu.c.chen@xxxxxxxxx
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/kernel/irq/matrix.c b/kernel/irq/matrix.c
index 8e586858bcf41..d25edbb87119f 100644
--- a/kernel/irq/matrix.c
+++ b/kernel/irq/matrix.c
@@ -466,16 +466,16 @@ unsigned int irq_matrix_reserved(struct irq_matrix *m)
 }
 
 /**
- * irq_matrix_allocated - Get the number of allocated irqs on the local cpu
+ * irq_matrix_allocated - Get the number of allocated non-managed irqs on the local CPU
  * @m:		Pointer to the matrix to search
  *
- * This returns number of allocated irqs
+ * This returns number of allocated non-managed interrupts.
  */
 unsigned int irq_matrix_allocated(struct irq_matrix *m)
 {
 	struct cpumap *cm = this_cpu_ptr(m->maps);
 
-	return cm->allocated;
+	return cm->allocated - cm->managed_allocated;
 }
 
 #ifdef CONFIG_GENERIC_IRQ_DEBUGFS



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