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x86: irq: Get correct available vectors for cpu disable 

check_irq_vectors_for_cpu_disable() can overestimate the number of
available interrupt vectors, so the check for cpu down succeeds, but
the actual cpu removal fails.

It iterates from FIRST_EXTERNAL_VECTOR to NR_VECTORS, which is wrong
because the systems vectors are not taken into account.

Limit the search to first_system_vector instead of NR_VECTORS.

The second indicator for vector availability the used_vectors bitmap
is not taken into account at all. So system vectors,
e.g. IA32_SYSCALL_VECTOR (0x80) and IRQ_MOVE_CLEANUP_VECTOR (0x20),
are accounted as available.

Add a check for the used_vectors bitmap and do not account vectors
which are marked there.

[ tglx: Simplified code. Rewrote changelog and code comments. ]

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Steven Rostedt (Red Hat) <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Elliott, Robert (Server Storage)" <Elliott@hp.com>
Cc: x86@kernel.org
Link: http://lkml.kernel.org/r/1400160305-17774-2-git-send-email-prarit@redhat.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
hifive-unleashed-5.1
Yinghai Lu 2014-05-13 11:39:34 -04:00 committed by Thomas Gleixner
parent d2cfd31050
commit ac2a55395e
1 changed files with 12 additions and 4 deletions
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16
arch/x86/kernel/irq.c
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@ -17,6 +17,7 @@
#include <asm/idle.h>
#include <asm/mce.h>
#include <asm/hw_irq.h>
#include <asm/desc.h>
#define CREATE_TRACE_POINTS
#include <asm/trace/irq_vectors.h>
@ -334,10 +335,17 @@ int check_irq_vectors_for_cpu_disable(void)
for_each_online_cpu(cpu) {
if (cpu == this_cpu)
continue;
for (vector = FIRST_EXTERNAL_VECTOR; vector < NR_VECTORS;
vector++) {
if (per_cpu(vector_irq, cpu)[vector] < 0)
count++;
/*
* We scan from FIRST_EXTERNAL_VECTOR to first system
* vector. If the vector is marked in the used vectors
* bitmap or an irq is assigned to it, we don't count
* it as available.
*/
for (vector = FIRST_EXTERNAL_VECTOR;
vector < first_system_vector; vector++) {
if (!test_bit(vector, used_vectors) &&
per_cpu(vector_irq, cpu)[vector] < 0)
count++;
}
}