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When preemption is enabled in kernel and if any task which can be preempted should not use smp_processor_id() directly, since CPU switch can happen at any time, the previous value of cpu_id differs with current cpu_id. As a result we see the below call trace during xlnx_event_manager_probe. [ 6.140197] dump_backtrace+0x0/0x190 [ 6.143884] show_stack+0x18/0x40 [ 6.147220] dump_stack_lvl+0x7c/0xa0 [ 6.150907] dump_stack+0x18/0x34 [ 6.154241] check_preemption_disabled+0x124/0x134 [ 6.159068] debug_smp_processor_id+0x20/0x2c [ 6.163453] xlnx_event_manager_probe+0x48/0x250 To protect cpu_id, It is recommended to use get_cpu()/put_cpu() to disable preemption, get the cpu_id and enable preemption respectively. (For Reference, Documentation/locking/preempt-locking.rst and Documentation/kernel-hacking/hacking.rst) Use preempt_disable()/smp_processor_id()/preempt_enable() API's to achieve the same. Signed-off-by: HariBabu Gattem <haribabu.gattem@xilinx.com> Signed-off-by: Jay Buddhabhatti <jay.buddhabhatti@amd.com> Link: https://lore.kernel.org/r/20231027055622.21544-1-jay.buddhabhatti@amd.com Signed-off-by: Michal Simek <michal.simek@amd.com> |
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