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Date:   Tue, 12 Sep 2023 15:14:28 +0800 (CST)
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From: Wang Yong <wang.yong12@zte.com.cn>

The ltp test prompts the following bug information under the 5.10 kernel:
BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:969
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 796, name: cat
Preemption disabled at:
[<ffffffe40f433980>] do_debug_exception+0x60/0x180
CPU: 3 PID: 796 Comm: cat Not tainted 5.10.59-rt52-KERNEL_VERSION #38
Hardware name: linux,dummy-virt (DT)
Call trace:
 dump_backtrace+0x0/0x198
 show_stack+0x20/0x30
 dump_stack+0xf0/0x13c
 ___might_sleep+0x140/0x178
 rt_spin_lock+0x30/0x90
 force_sig_info_to_task+0x30/0xe0
 force_sig_fault_to_task+0x54/0x78
 force_sig_fault+0x1c/0x28
 arm64_force_sig_fault+0x48/0x78
 send_user_sigtrap+0x4c/0x80
 brk_handler+0x3c/0x68
 do_debug_exception+0xac/0x180
 el0_dbg+0x34/0x58
 el0_sync_handler+0x50/0xb8
 el0_sync+0x180/0x1c0

It has been fixed by
0c34700de5e7 ("arm64: signal: Use ARCH_RT_DELAYS_SIGNAL_SEND.") in
higher versions of the kernel. This patch needs to be compatible with 5.10.
5.10 kernel does not have signal.h file, so adding signal.h file to
define ARCH_RT_DELAYS_SIGNAL_SEND.

Signed-off-by: Wang Yong <wang.yong12@zte.com.cn>
Cc: Xuexin Jiang <jiang.xuexin@zte.com.cn>
Cc: Yang Yang <yang.yang29@zte.com.cn>
Cc: Xiaokai Ran <ran.xiaokai@zte.com.cn>
---
 arch/arm64/include/asm/signal.h | 12 ++++++++++++
 arch/arm64/kernel/signal.c      |  9 +++++++++
 2 files changed, 21 insertions(+)
 create mode 100644 arch/arm64/include/asm/signal.h

diff --git a/arch/arm64/include/asm/signal.h b/arch/arm64/include/asm/signal.h
new file mode 100644
index 000000000..0fb418cf4
--- /dev/null
+++ b/arch/arm64/include/asm/signal.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ARM64_ASM_SIGNAL_H
+#define __ARM64_ASM_SIGNAL_H
+
+#include <uapi/asm/signal.h>
+#include <uapi/asm/siginfo.h>
+
+#if defined(CONFIG_PREEMPT_RT)
+#define ARCH_RT_DELAYS_SIGNAL_SEND
+#endif
+
+#endif
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index fe94a3e1f..538d4aadb 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -927,6 +927,15 @@ asmlinkage void do_notify_resume(struct pt_regs *regs,
 		} else {
 			local_daif_restore(DAIF_PROCCTX);

+#ifdef ARCH_RT_DELAYS_SIGNAL_SEND
+			if (unlikely(current->forced_info.si_signo)) {
+				struct task_struct *t = current;
+
+				force_sig_info(&t->forced_info);
+				t->forced_info.si_signo = 0;
+			}
+#endif
+
 			if (thread_flags & _TIF_UPROBE)
 				uprobe_notify_resume(regs);

-- 
2.25.1