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A call to exit the PMU state machine/kthread must be prioritized over any other state change. It was possible to set the state as PMU_STATE_EXIT, signal the kthread and overwrite the state before the kthread has had the chance to exit its loop. This may lead to a "lost" signal, resulting in indefinite wait during the destroy sequence. Faulting sequence: 1. pmu_state = PMU_STATE_EXIT in nvgpu_pmu_destroy() 2. cond_signal() 3. pmu_state = PMU_STATE_LOADING_PG_BUF 4. PMU kthread wakes up 5. PMU kthread processes PMU_STATE_LOADING_PG_BUF 6. PMU kthread sleeps 7. nvgpu_pmu_destroy() waits indefinitely This patch adds a sticky flag to indicate PMU_STATE_EXIT, irrespective of any subsequent changes to pmu_state. The PMU PG init kthread may wait on a call to NVGPU_COND_WAIT_INTERRUPTIBLE, which requires a corresponding call to nvgpu_cond_signal_interruptible() as the core kernel code requires this task mask to wake-up an interruptible task. Bug 2658750 Bug 200532122 Change-Id: I61beae80673486f83bf60c703a8af88b066a1c36 Signed-off-by: Divya Singhatwaria <dsinghatwari@nvidia.com> Reviewed-on: https://git-master.nvidia.com/r/2181926 Reviewed-by: svc-mobile-coverity <svc-mobile-coverity@nvidia.com> Reviewed-by: svc-mobile-misra <svc-mobile-misra@nvidia.com> Reviewed-by: Mahantesh Kumbar <mkumbar@nvidia.com> GVS: Gerrit_Virtual_Submit Reviewed-by: Deepak Nibade <dnibade@nvidia.com> Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com> Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>