Re: [PATCH 0/6] Allow signals for IO threads

Stefan Metzmacher
2021-03-27T01:47:36Z

Hi Jens,

> root@ub1704-166:~# LANG=C gdb --pid 1320
> GNU gdb (Ubuntu 9.2-0ubuntu1~20.04) 9.2
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> Attaching to process 1320
> [New LWP 1321]
> [New LWP 1322]
>
> warning: Selected architecture i386:x86-64 is not compatible with reported target architecture i386
>
> warning: Architecture rejected target-supplied description
> syscall () at ../sysdeps/unix/sysv/linux/x86_64/syscall.S:38
> 38 ../sysdeps/unix/sysv/linux/x86_64/syscall.S: No such file or directory.
> (gdb)

Ok, the following makes gdb happy again:

--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -163,6 +163,8 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg,
/* Kernel thread ? */
if (unlikely(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
memset(childregs, 0, sizeof(struct pt_regs));
+ if (p->flags & PF_IO_WORKER)
+ childregs->cs = current_pt_regs()->cs;
kthread_frame_init(frame, sp, arg);
return 0;
}

I'm wondering if we should decouple the PF_KTHREAD and PF_IO_WORKER cases even more
and keep as much of a userspace-like copy_thread as possible.

metze