[PATCH] soc: fsl: dpio: protect smp_processor_id when get processor id
Robin Murphy
robin.murphy at arm.com
Fri Oct 15 06:39:50 PDT 2021
On 2021-10-15 07:36, Meng.Li at windriver.com wrote:
> From: Meng Li <meng.li at windriver.com>
>
> When enable debug kernel configs,there will be calltrace as below:
>
> BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1
> caller is debug_smp_processor_id+0x20/0x30
> CPU: 6 PID: 1 Comm: swapper/0 Not tainted 5.10.63-yocto-standard #1
> Hardware name: NXP Layerscape LX2160ARDB (DT)
> Call trace:
> dump_backtrace+0x0/0x1a0
> show_stack+0x24/0x30
> dump_stack+0xf0/0x13c
> check_preemption_disabled+0x100/0x110
> debug_smp_processor_id+0x20/0x30
> dpaa2_io_query_fq_count+0xdc/0x154
> dpaa2_eth_stop+0x144/0x314
> __dev_close_many+0xdc/0x160
> __dev_change_flags+0xe8/0x220
> dev_change_flags+0x30/0x70
> ic_close_devs+0x50/0x78
> ip_auto_config+0xed0/0xf10
> do_one_initcall+0xac/0x460
> kernel_init_freeable+0x30c/0x378
> kernel_init+0x20/0x128
> ret_from_fork+0x10/0x38
>
> Because smp_processor_id() should be invoked in preempt disable status.
> So, add preempt_disable/enable() to protect smp_processor_id().
If preemption doesn't matter anyway, as the comment in the context
implies, then it probably makes more sense just to use
raw_smp_processor_id() instead.
Robin.
> Fixes: c89105c9b390 ("staging: fsl-mc: Move DPIO from staging to drivers/soc/fsl")
> Cc: stable at vger.kernel.org
> Signed-off-by: Meng Li <Meng.Li at windriver.com>
> ---
> drivers/soc/fsl/dpio/dpio-service.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/soc/fsl/dpio/dpio-service.c b/drivers/soc/fsl/dpio/dpio-service.c
> index 19f47ea9dab0..afc3b89b0fc5 100644
> --- a/drivers/soc/fsl/dpio/dpio-service.c
> +++ b/drivers/soc/fsl/dpio/dpio-service.c
> @@ -58,8 +58,11 @@ static inline struct dpaa2_io *service_select_by_cpu(struct dpaa2_io *d,
> * If cpu == -1, choose the current cpu, with no guarantees about
> * potentially being migrated away.
> */
> - if (cpu < 0)
> - cpu = smp_processor_id();
> + if (cpu < 0) {
> + preempt_disable();
> + cpu = smp_processor_id();
> + preempt_enable();
> + }
>
> /* If a specific cpu was requested, pick it up immediately */
> return dpio_by_cpu[cpu];
>
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