tree 1c2b6ff25ed7291973cb63f3c441fc8d7e8c43f9
parent f1013d8405af0f4fe1812b5901cbac9ce4d1fb6f
author HariBabu Gattem <haribabu.gattem@xilinx.com> 1698386182 -0700
committer Michal Simek <michal.simek@amd.com> 1700056945 +0100

soc: xilinx: Fix for call trace due to the usage of smp_processor_id()

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>