Re: [PATCH 5.10-rt] arm64: signal: Use ARCH_RT_DELAYS_SIGNAL_SEND

[Luis Claudio R. Goncalves]

On Tue, Sep 12, 2023 at 03:14:28PM +0800, yang.yang29@xxxxxxxxxx wrote:
> From: Wang Yong <wang.yong12@xxxxxxxxxx>
> 
> 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@xxxxxxxxxx>
> Cc: Xuexin Jiang <jiang.xuexin@xxxxxxxxxx>
> Cc: Yang Yang <yang.yang29@xxxxxxxxxx>
> Cc: Xiaokai Ran <ran.xiaokai@xxxxxxxxxx>
> ---

Thank you for this fix. I will add it to the release candidate that will
be posted on Friday.

Best regards,
Luis

>  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
> 
---end quoted text---