Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S938964AbZDJRRJ (ORCPT ); Fri, 10 Apr 2009 13:17:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S938583AbZDJRQA (ORCPT ); Fri, 10 Apr 2009 13:16:00 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:57759 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S938784AbZDJRP7 (ORCPT ); Fri, 10 Apr 2009 13:15:59 -0400 Date: Fri, 10 Apr 2009 18:14:15 +0100 From: Al Viro To: Linus Torvalds Cc: Ingo Molnar , Tejun Heo , Mike Travis , Christoph Lameter , Heiko Carstens , Martin Schwidefsky , Linux Kernel Mailing List Subject: Re: [PATCH] unbreak alpha percpu Message-ID: <20090410171415.GA6033@ZenIV.linux.org.uk> References: <20090410151224.GM26366@ZenIV.linux.org.uk> <20090410154704.GN26366@ZenIV.linux.org.uk> <20090410165030.GQ26366@ZenIV.linux.org.uk> <20090410170507.GR26366@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090410170507.GR26366@ZenIV.linux.org.uk> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7157 Lines: 201 On Fri, Apr 10, 2009 at 06:05:07PM +0100, Al Viro wrote: > On Fri, Apr 10, 2009 at 05:50:30PM +0100, Al Viro wrote: > > On Fri, Apr 10, 2009 at 09:21:08AM -0700, Linus Torvalds wrote: > > > > > > Hmm. I certainly personally _much_ prefer this version. > > > > > > It looks like this actually simplifies things for S390 too (no more > > > simple_identifier_##var games), and generally just looks better. And > > > seeing that the S390 special case is no longer S390-specific is also a > > > good sign, imho. > > > > simple_identifier_##var has been debris from back when Ingo forced > > s390 to use asm-generic/percpu.h; if you look at it, you'll see that > > a) it hadn't worked (look at the argument list carefully) and > > b) get_cpu_var() has the working version anyway > > > > Less obvious part is that if it actually *would* work, we'd be screwed - > > unlike get_cpu_var() this sucker is called for things that are not > > simple variables; didn't happen for alpha, but did for s390. > > > > IOW, that's just an old piece of junk that got removed now. > > Fsck... It breaks per_cpu_ptr() :-/ OK, back to square one, then... ... and the reason we didn't step into that one on alpha et.al. is that it doesn't have HAVE_DYNAMIC_PER_CPU_AREA - only x86 does. It's *still* fixable, but we need a different primitive for that one. diff --git a/arch/alpha/include/asm/percpu.h b/arch/alpha/include/asm/percpu.h index 3495e8e..1c52a2d 100644 --- a/arch/alpha/include/asm/percpu.h +++ b/arch/alpha/include/asm/percpu.h @@ -3,33 +3,8 @@ #include #include -/* - * Determine the real variable name from the name visible in the - * kernel sources. - */ -#define per_cpu_var(var) per_cpu__##var - #ifdef CONFIG_SMP - -/* - * per_cpu_offset() is the offset that has to be added to a - * percpu variable to get to the instance for a certain processor. - */ -extern unsigned long __per_cpu_offset[NR_CPUS]; - -#define per_cpu_offset(x) (__per_cpu_offset[x]) - -#define __my_cpu_offset per_cpu_offset(raw_smp_processor_id()) -#ifdef CONFIG_DEBUG_PREEMPT -#define my_cpu_offset per_cpu_offset(smp_processor_id()) -#else -#define my_cpu_offset __my_cpu_offset -#endif - -#ifndef MODULE -#define SHIFT_PERCPU_PTR(var, offset) RELOC_HIDE(&per_cpu_var(var), (offset)) -#define PER_CPU_ATTRIBUTES -#else +#ifdef MODULE /* * To calculate addresses of locally defined variables, GCC uses 32-bit * displacement from the GP. Which doesn't work for per cpu variables in @@ -39,40 +14,15 @@ extern unsigned long __per_cpu_offset[NR_CPUS]; * ldq instruction with a 'literal' relocation. */ #define SHIFT_PERCPU_PTR(var, offset) ({ \ - extern int simple_identifier_##var(void); \ unsigned long __ptr, tmp_gp; \ asm ( "br %1, 1f \n\ 1: ldgp %1, 0(%1) \n\ ldq %0, per_cpu__" #var"(%1)\t!literal" \ : "=&r"(__ptr), "=&r"(tmp_gp)); \ (typeof(&per_cpu_var(var)))(__ptr + (offset)); }) - -#define PER_CPU_ATTRIBUTES __used - #endif /* MODULE */ - -/* - * A percpu variable may point to a discarded regions. The following are - * established ways to produce a usable pointer from the percpu variable - * offset. - */ -#define per_cpu(var, cpu) \ - (*SHIFT_PERCPU_PTR(var, per_cpu_offset(cpu))) -#define __get_cpu_var(var) \ - (*SHIFT_PERCPU_PTR(var, my_cpu_offset)) -#define __raw_get_cpu_var(var) \ - (*SHIFT_PERCPU_PTR(var, __my_cpu_offset)) - -#else /* ! SMP */ - -#define per_cpu(var, cpu) (*((void)(cpu), &per_cpu_var(var))) -#define __get_cpu_var(var) per_cpu_var(var) -#define __raw_get_cpu_var(var) per_cpu_var(var) - -#define PER_CPU_ATTRIBUTES - #endif /* SMP */ -#define DECLARE_PER_CPU(type, name) extern __typeof__(type) per_cpu_var(name) +#include #endif /* __ALPHA_PERCPU_H */ diff --git a/arch/s390/include/asm/percpu.h b/arch/s390/include/asm/percpu.h index 408d60b..6a71d73 100644 --- a/arch/s390/include/asm/percpu.h +++ b/arch/s390/include/asm/percpu.h @@ -13,20 +13,18 @@ */ #if defined(__s390x__) && defined(MODULE) -#define SHIFT_PERCPU_PTR(ptr,offset) (({ \ - extern int simple_identifier_##var(void); \ +#define SHIFT_PERCPU_PTR(var,offset) (({ \ unsigned long *__ptr; \ asm ( "larl %0, %1@GOTENT" \ - : "=a" (__ptr) : "X" (ptr) ); \ - (typeof(ptr))((*__ptr) + (offset)); })) + : "=a" (__ptr) : "X" (&per_cpu_var(var)) ); \ + (typeof(&per_cpu_var(var)))((*__ptr) + (offset)); })) #else -#define SHIFT_PERCPU_PTR(ptr, offset) (({ \ - extern int simple_identifier_##var(void); \ +#define SHIFT_PERCPU_PTR(var, offset) (({ \ unsigned long __ptr; \ - asm ( "" : "=a" (__ptr) : "0" (ptr) ); \ - (typeof(ptr)) (__ptr + (offset)); })) + asm ( "" : "=a" (__ptr) : "0" (&per_cpu_var(var)) ); \ + (typeof(&per_cpu_var(var))) (__ptr + (offset)); })) #endif diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h index aee103b..5ff94d2 100644 --- a/arch/x86/include/asm/percpu.h +++ b/arch/x86/include/asm/percpu.h @@ -202,4 +202,6 @@ DECLARE_PER_CPU(unsigned long, this_cpu_off); #endif /* !CONFIG_SMP */ +#define PERCPU_PTR RELOC_HIDE + #endif /* _ASM_X86_PERCPU_H */ diff --git a/include/asm-generic/percpu.h b/include/asm-generic/percpu.h index 00f45ff..4543078 100644 --- a/include/asm-generic/percpu.h +++ b/include/asm-generic/percpu.h @@ -42,10 +42,10 @@ extern unsigned long __per_cpu_offset[NR_CPUS]; /* * Add a offset to a pointer but keep the pointer as is. * - * Only S390 provides its own means of moving the pointer. + * Only S390 and Alpha provide their own means of moving the pointer. */ #ifndef SHIFT_PERCPU_PTR -#define SHIFT_PERCPU_PTR(__p, __offset) RELOC_HIDE((__p), (__offset)) +#define SHIFT_PERCPU_PTR(__v, __offset) RELOC_HIDE((&per_cpu_var(__v)), (__offset)) #endif /* @@ -54,11 +54,11 @@ extern unsigned long __per_cpu_offset[NR_CPUS]; * offset. */ #define per_cpu(var, cpu) \ - (*SHIFT_PERCPU_PTR(&per_cpu_var(var), per_cpu_offset(cpu))) + (*SHIFT_PERCPU_PTR(var, per_cpu_offset(cpu))) #define __get_cpu_var(var) \ - (*SHIFT_PERCPU_PTR(&per_cpu_var(var), my_cpu_offset)) + (*SHIFT_PERCPU_PTR(var, my_cpu_offset)) #define __raw_get_cpu_var(var) \ - (*SHIFT_PERCPU_PTR(&per_cpu_var(var), __my_cpu_offset)) + (*SHIFT_PERCPU_PTR(var, __my_cpu_offset)) #ifdef CONFIG_HAVE_SETUP_PER_CPU_AREA diff --git a/include/linux/percpu.h b/include/linux/percpu.h index ee5615d..11a8a11 100644 --- a/include/linux/percpu.h +++ b/include/linux/percpu.h @@ -120,7 +120,7 @@ extern ssize_t __init pcpu_embed_first_chunk( * dynamically allocated. Non-atomic access to the current CPU's * version should probably be combined with get_cpu()/put_cpu(). */ -#define per_cpu_ptr(ptr, cpu) SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu))) +#define per_cpu_ptr(ptr, cpu) PERCPU_PTR((ptr), per_cpu_offset((cpu))) extern void *__alloc_reserved_percpu(size_t size, size_t align); -- 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/