Messages in this thread | | | Date | Tue, 11 Dec 2012 16:04:55 +0800 | From | Zhang Yanfei <> | Subject | Re: [PATCH] x86/kexec: crash_vmclear_local_vmcss needs __rcu |
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于 2012年12月11日 04:30, Marcelo Tosatti 写道: > On Fri, Dec 07, 2012 at 01:40:56PM +0800, Zhang Yanfei wrote: >> This removes the sparse warning: >> arch/x86/kernel/crash.c:49:32: sparse: incompatible types in comparison expression (different address spaces) >> >> Reported-by: kbuild test robot <fengguang.wu@intel.com> >> Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> >> --- >> arch/x86/include/asm/kexec.h | 4 +++- >> arch/x86/kernel/crash.c | 4 ++-- >> 2 files changed, 5 insertions(+), 3 deletions(-) >> >> diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h >> index 28feeba..16882cd 100644 >> --- a/arch/x86/include/asm/kexec.h >> +++ b/arch/x86/include/asm/kexec.h >> @@ -163,7 +163,9 @@ struct kimage_arch { >> }; >> #endif >> >> -extern void (*crash_vmclear_loaded_vmcss)(void); >> +extern void __rcu (*crash_vmclear_loaded_vmcss)(void); >> +#define vmclear_func_rcu(vmclear_func) \ >> + ((void (*)(void)) rcu_dereference(vmclear_func)) >> >> #endif /* __ASSEMBLY__ */ >> >> diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c >> index 2f6b8e8..50ce1d6 100644 >> --- a/arch/x86/kernel/crash.c >> +++ b/arch/x86/kernel/crash.c >> @@ -38,7 +38,7 @@ int in_crash_kexec; >> * >> * protected by rcu. >> */ >> -void (*crash_vmclear_loaded_vmcss)(void) = NULL; >> +void __rcu (*crash_vmclear_loaded_vmcss)(void) = NULL; > > Isnt this (__rcu AS tag) sufficient? After all, sparse is complaining > about namespaces. > > Creating a #define to cast seems excessive. > >
I am not very familiar with the rcu. Adding __rcu tag could solve the problem. But it imported another warning when I try to assign rcu_dereference(crash_vmclear_loaded_vmcss) to do_vmclear_operation:
arch/x86/kernel/crash.c:49:30: warning: incorrect type in assignment (different modifiers) arch/x86/kernel/crash.c:49:30: expected void ( *do_vmclear_operation )( ... ) arch/x86/kernel/crash.c:49:30: got void ( [noderef] *<noident> )( ... ) arch/x86/kernel/crash.c:49:30: warning: incorrect type in assignment (different modifiers) arch/x86/kernel/crash.c:49:30: expected void ( *do_vmclear_operation )( ... ) arch/x86/kernel/crash.c:49:30: got void ( [noderef] *<noident> )( ... )
So I made the #define to cast its type.
If you have any suggestion, that'll be helpful.
Thanks Zhang Yanfei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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