6.6-stable review patch. If anyone has any objections, please let me know.
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From: HariBabu Gattem haribabu.gattem@xilinx.com
[ Upstream commit daed80ed07580e5adc0e6d8bc79933a35154135a ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/soc/xilinx/xlnx_event_manager.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/soc/xilinx/xlnx_event_manager.c b/drivers/soc/xilinx/xlnx_event_manager.c index 86a048a10a13..edfb1d5c10c6 100644 --- a/drivers/soc/xilinx/xlnx_event_manager.c +++ b/drivers/soc/xilinx/xlnx_event_manager.c @@ -555,7 +555,7 @@ static void xlnx_disable_percpu_irq(void *data) static int xlnx_event_init_sgi(struct platform_device *pdev) { int ret = 0; - int cpu = smp_processor_id(); + int cpu; /* * IRQ related structures are used for the following: * for each SGI interrupt ensure its mapped by GIC IRQ domain @@ -592,9 +592,12 @@ static int xlnx_event_init_sgi(struct platform_device *pdev) sgi_fwspec.param[0] = sgi_num; virq_sgi = irq_create_fwspec_mapping(&sgi_fwspec);
+ cpu = get_cpu(); per_cpu(cpu_number1, cpu) = cpu; ret = request_percpu_irq(virq_sgi, xlnx_event_handler, "xlnx_event_mgmt", &cpu_number1); + put_cpu(); + WARN_ON(ret); if (ret) { irq_dispose_mapping(virq_sgi);