From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from natsmtp00.rzone.de ([81.169.145.165]:55977 "EHLO natsmtp00.rzone.de") by vger.kernel.org with ESMTP id S264379AbUEDOSS convert rfc822-to-8bit (ORCPT ); Tue, 4 May 2004 10:18:18 -0400 From: Arnd Bergmann Subject: Re: static DEFINE_PER_CPU vs. modules Date: Tue, 4 May 2004 16:17:29 +0200 References: <200405031741.52504.arnd@arndb.de> <20040503193835.72c62ad8.akpm@osdl.org> In-Reply-To: <20040503193835.72c62ad8.akpm@osdl.org> MIME-Version: 1.0 Content-Disposition: inline Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8BIT Message-Id: <200405041617.37371.arnd@arndb.de> To: Andrew Morton Cc: rusty@rustcorp.com.au, linux-arch@vger.kernel.org, epasch@de.ibm.com, hare@suse.de List-ID: On Tuesday 04 May 2004 04:38, Andrew Morton wrote: > Arnd Bergmann wrote: > > > > The idea I had for preventing the same bug from happening > >  in the future is to provoke a compile error for modules using > >  'static DEFINE_PER_CPU', see patch below. > > It's not a big success with CONFIG_SMP=n. > > kernel/fork.c:55: warning: return-type defaults to `int' > kernel/fork.c: In function `__PER_CPU_NOSTATIC': Sorry about that, I accidentally defined __PER_CPU_NOSTATIC inside '#ifdef CONFIG_SMP'. This now builds with and without SMP. Arnd <>< ===== drivers/scsi/scsi.c 1.142 vs edited ===== --- 1.142/drivers/scsi/scsi.c Sun Apr 4 17:01:05 2004 +++ edited/drivers/scsi/scsi.c Thu Apr 29 17:59:34 2004 @@ -672,7 +672,7 @@ /* * Per-CPU I/O completion queue. */ -static DEFINE_PER_CPU(struct list_head, scsi_done_q); +DEFINE_PER_CPU(struct list_head, scsi_done_q); /** * scsi_done - Enqueue the finished SCSI command into the done queue. ===== include/asm-generic/percpu.h 1.10 vs edited ===== --- 1.10/include/asm-generic/percpu.h Mon Jan 19 07:28:34 2004 +++ edited/include/asm-generic/percpu.h Tue May 4 15:59:18 2004 @@ -3,12 +3,23 @@ #include #define __GENERIC_PER_CPU + +/* modules must not use "static DEFINE_PER_CPU", so add an + * extern declaration that causes a compile error if somebody + * attempts */ +#ifndef MODULE +#define __PER_CPU_NOSTATIC(decl) +#else +#define __PER_CPU_NOSTATIC(decl) extern decl; +#endif + #ifdef CONFIG_SMP extern unsigned long __per_cpu_offset[NR_CPUS]; /* Separate out the type, so (int[3], foo) works. */ #define DEFINE_PER_CPU(type, name) \ + __PER_CPU_NOSTATIC(__typeof__(type) per_cpu__##name) \ __attribute__((__section__(".data.percpu"))) __typeof__(type) per_cpu__##name /* var is in discarded region: offset to particular copy we want */ @@ -27,6 +38,7 @@ #else /* ! SMP */ #define DEFINE_PER_CPU(type, name) \ + __PER_CPU_NOSTATIC(__typeof__(type) per_cpu__##name) \ __typeof__(type) per_cpu__##name #define per_cpu(var, cpu) (*((void)cpu, &per_cpu__##var)) ===== net/ipv6/icmp.c 1.49 vs edited ===== --- 1.49/net/ipv6/icmp.c Fri Apr 16 22:54:44 2004 +++ edited/net/ipv6/icmp.c Thu Apr 29 17:59:58 2004 @@ -76,7 +76,7 @@ * * On SMP we have one ICMP socket per-cpu. */ -static DEFINE_PER_CPU(struct socket *, __icmpv6_socket) = NULL; +DEFINE_PER_CPU(struct socket *, __icmpv6_socket) = NULL; #define icmpv6_socket __get_cpu_var(__icmpv6_socket) static int icmpv6_rcv(struct sk_buff **pskb, unsigned int *nhoffp);