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From:   Meng.Li@windriver.com
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Subject: [PATCH] soc: fsl: dpio: protect smp_processor_id when get processor id
Date:   Fri, 15 Oct 2021 14:36:01 +0800
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From: Meng Li <meng.li@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().

Fixes: c89105c9b390 ("staging: fsl-mc: Move DPIO from staging to drivers/soc/fsl")
Cc: stable@vger.kernel.org
Signed-off-by: Meng Li <Meng.Li@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];
-- 
2.17.1