From d8b833d78f6bfde9855a949b5e6d3790d78c0fb7 Mon Sep 17 00:00:00 2001 From: Gregory Herrero Date: Thu, 1 Jun 2017 10:53:04 +0200 Subject: [PATCH] stop_machine: fill fn_result only in case of error When stop_machine_run() is called with NR_CPUS as last argument, fn_result member must be filled only if an error happens since it is shared across all cpus. Assume CPU1 detects an error and set fn_result to -1, then CPU2 doesn't detect an error and set fn_result to 0. The error detected by CPU1 will be ignored. Note that in case multiple failures occur on different CPUs, only the last error will be reported. Signed-off-by: Gregory Herrero Reviewed-by: Wei Liu --- xen/common/stop_machine.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/xen/common/stop_machine.c b/xen/common/stop_machine.c index 304b783aae..ce6f5624c4 100644 --- a/xen/common/stop_machine.c +++ b/xen/common/stop_machine.c @@ -94,6 +94,7 @@ int stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu) stopmachine_data.fn_data = data; stopmachine_data.nr_cpus = nr_cpus; stopmachine_data.fn_cpu = cpu; + stopmachine_data.fn_result = 0; atomic_set(&stopmachine_data.done, 0); stopmachine_data.state = STOPMACHINE_START; @@ -112,7 +113,11 @@ int stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu) stopmachine_set_state(STOPMACHINE_INVOKE); if ( (cpu == smp_processor_id()) || (cpu == NR_CPUS) ) - stopmachine_data.fn_result = (*fn)(data); + { + ret = (*fn)(data); + if ( ret ) + write_atomic(&stopmachine_data.fn_result, ret); + } stopmachine_wait_state(); ret = stopmachine_data.fn_result; @@ -150,8 +155,12 @@ static void stopmachine_action(unsigned long cpu) case STOPMACHINE_INVOKE: if ( (stopmachine_data.fn_cpu == smp_processor_id()) || (stopmachine_data.fn_cpu == NR_CPUS) ) - stopmachine_data.fn_result = - stopmachine_data.fn(stopmachine_data.fn_data); + { + int ret = stopmachine_data.fn(stopmachine_data.fn_data); + + if ( ret ) + write_atomic(&stopmachine_data.fn_result, ret); + } break; default: break; -- 2.30.2