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cpus-common: ensure auto-assigned cpu_indexes don't clash 

Basing the cpu_index on the number of currently allocated vCPUs fails
when vCPUs aren't removed in a LIFO manner. This is especially true
when we are allocating a cpu_index for each guest thread in
linux-user where there is no ordering constraint on their allocation
and de-allocation.

[I've dropped the assert which is there to guard against out-of-order
removal as this should probably be caught higher up the stack. Maybe
we could just ifdef CONFIG_SOFTTMU it?]

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Acked-by: Igor Mammedow <imammedo@redhat.com>
Cc: Nikolay Igotti <igotti@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20200520140541.30256-13-alex.bennee@linaro.org>
This commit is contained in:
Alex Bennée 2020-05-20 15:05:38 +01:00
parent c729a99d27
commit 716386e397
1 changed files with 5 additions and 5 deletions
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10
cpus-common.c
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@ -61,13 +61,15 @@ static bool cpu_index_auto_assigned;
static int cpu_get_free_index(void)
{
CPUState *some_cpu;
int cpu_index = 0;
int max_cpu_index = 0;
cpu_index_auto_assigned = true;
CPU_FOREACH(some_cpu) {
cpu_index++;
if (some_cpu->cpu_index >= max_cpu_index) {
max_cpu_index = some_cpu->cpu_index + 1;
}
}
return cpu_index;
return max_cpu_index;
}
void cpu_list_add(CPUState *cpu)
@ -90,8 +92,6 @@ void cpu_list_remove(CPUState *cpu)
return;
}
assert(!(cpu_index_auto_assigned && cpu != QTAILQ_LAST(&cpus)));
QTAILQ_REMOVE_RCU(&cpus, cpu, node);
cpu->cpu_index = UNASSIGNED_CPU_INDEX;
}