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authorShreyas B. Prabhu <shreyas@linux.vnet.ibm.com>2015-05-20 00:30:14 +0530
committerMichael Ellerman <mpe@ellerman.id.au>2015-06-17 08:01:03 +1000
commit3609d819a36c65857816ca1278d80767d6d9b990 (patch)
treef74a540fb015f9774a22753e4665a1b5aec689b7 /arch/powerpc/sysdev/xics
parent4bece972fce6e597cb513bdcae4a04e14fc0dd81 (diff)
powerpc: Make doorbell check preemption safe
Doorbell can be used to cause ipi on cpus which are sibling threads on the same core. So icp_native_cause_ipi checks if the destination cpu is a sibling thread of the current cpu and uses doorbell in such cases. But while running with CONFIG_PREEMPT=y, since this section is preemtible, we can run into issues if after we check if the destination cpu is a sibling cpu, the task gets migrated from a sibling cpu to a cpu on another core. Fix this by using get_cpu()/ put_cpu() Signed-off-by: Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com> Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/sysdev/xics')
-rw-r--r--arch/powerpc/sysdev/xics/icp-native.c14
1 files changed, 9 insertions, 5 deletions
diff --git a/arch/powerpc/sysdev/xics/icp-native.c b/arch/powerpc/sysdev/xics/icp-native.c
index 2fc4cf1b7557..eae32654bdf2 100644
--- a/arch/powerpc/sysdev/xics/icp-native.c
+++ b/arch/powerpc/sysdev/xics/icp-native.c
@@ -147,12 +147,16 @@ static void icp_native_cause_ipi(int cpu, unsigned long data)
{
kvmppc_set_host_ipi(cpu, 1);
#ifdef CONFIG_PPC_DOORBELL
- if (cpu_has_feature(CPU_FTR_DBELL) &&
- (cpumask_test_cpu(cpu, cpu_sibling_mask(smp_processor_id()))))
- doorbell_cause_ipi(cpu, data);
- else
+ if (cpu_has_feature(CPU_FTR_DBELL)) {
+ if (cpumask_test_cpu(cpu, cpu_sibling_mask(get_cpu()))) {
+ doorbell_cause_ipi(cpu, data);
+ put_cpu();
+ return;
+ }
+ put_cpu();
+ }
#endif
- icp_native_set_qirr(cpu, IPI_PRIORITY);
+ icp_native_set_qirr(cpu, IPI_PRIORITY);
}
/*