Messages in this thread Patch in this message | | | Date | Wed, 27 Nov 2019 18:02:35 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH] ptrace/x86: introduce TS_COMPAT_RESTART to fix get_nr_restart_syscall() |
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On 11/26, Linus Torvalds wrote: > > On Tue, Nov 26, 2019 at 3:08 AM Oleg Nesterov <oleg@redhat.com> wrote: > > > > Alternatively we could add ->compat_restart into struct restart_block, > > logically this is the same thing. > > That sounds like the better model to me. That's what the restart_block > is about: it's supposed to contain the restart information.
I knew ;) OK, I won't argue, I'll send V2.
> I'd much rather see the system call number added into the restart > block (or just the "compat bit" - but we have that X32 case too, so > why not put it all there).
apart from x86, who else can use it? after the quick grep I think nobody, even arm64 and mips which have compat nr_restart's do not need it.
restart_block.arch_restart_block_infp makes more sense, but that would be even more painful, I do not want to add asm/restart_block.h or HAVE_ARCH_RESTART_INFO, or use CONFIG_IA32_EMULATION.
OK, lets add the new restart_block.nr_restart_syscall field, then we need
void set_restart_block_fn(restart, fn) { restart->nr_restart_syscall = arch_get_nr_restart_syscall() restart->fn = fn; }
but somehow I do not see a good place for
#ifndef arch_get_nr_restart_syscall() #define arch_get_nr_restart_syscall() 0 #endif
Can you suggest a simple solution?
Hmm. Or may be HAVE_ARCH_RESTART is better after all? Say, just
--- a/include/linux/restart_block.h +++ b/include/linux/restart_block.h @@ -24,6 +24,9 @@ enum timespec_type { */ struct restart_block { long (*fn)(struct restart_block *); +#ifdef CONFIG_HAVE_ARCH_RESTART_XXX + int nr_restart_syscall; +#endif union { /* For futex_wait and futex_wait_requeue_pi */ struct { @@ -55,6 +58,15 @@ struct restart_block { }; }; +static inline void set_restart_block_fn(restart, fn) +{ +#ifdef CONFIG_HAVE_ARCH_RESTART_XXX + extern int arch_get_nr_restart_syscall(); + restart->nr_restart_syscall = arch_get_nr_restart_syscall(); +#endif + restart->fn = fn; +} + extern long do_no_restart_syscall(struct restart_block *parm); #endif /* __LINUX_RESTART_BLOCK_H */
?
Oleg.
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