Re: [PATCH v2 05/11] sched,livepatch: Use wake_up_if_idle()
From: Arnd Bergmann <arnd@kernel.org>
Date: 2021-10-13 19:37:22
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On Wed, Sep 29, 2021 at 6:10 PM Peter Zijlstra [off-list ref] wrote:
quoted hunk ↗ jump to hunk
Make sure to prod idle CPUs so they call klp_update_patch_state(). Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- kernel/livepatch/transition.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)--- a/kernel/livepatch/transition.c +++ b/kernel/livepatch/transition.c@@ -413,8 +413,11 @@ void klp_try_complete_transition(void) for_each_possible_cpu(cpu) { task = idle_task(cpu); if (cpu_online(cpu)) { - if (!klp_try_switch_task(task)) + if (!klp_try_switch_task(task)) { complete = false; + /* Make idle task go through the main loop. */ + wake_up_if_idle(cpu); + }
This caused a build regression on non-SMP kernels:
x86_64-linux-ld: kernel/livepatch/transition.o: in function
`klp_try_complete_transition':
transition.c:(.text+0x106e): undefined reference to `wake_up_if_idle'
Maybe add a IS_ENABLED(CONFIG_SMP) check to one of the if() conditions?
Arnd