Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 14 Feb 2003 06:43:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 14 Feb 2003 06:43:29 -0500 Received: from modemcable092.130-200-24.mtl.mc.videotron.ca ([24.200.130.92]:20311 "EHLO montezuma.mastecende.com") by vger.kernel.org with ESMTP id ; Fri, 14 Feb 2003 06:43:27 -0500 Date: Fri, 14 Feb 2003 06:51:54 -0500 (EST) From: Zwane Mwaikambo X-X-Sender: zwane@montezuma.mastecende.com To: Linux Kernel cc: Richard T Henderson , Linus Torvalds Subject: [PATCH][2.5] Protect smp_call_function_data w/ spinlocks on Alpha Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2352 Lines: 81 Hi Richard, This is an untested patch to remove the custom mutex, however it doesn't maintain the same semantics wrt 'retry' and unconditionally blocks on contention. A version of this patch is in the smp_call_function_on_cpu patch i posted for Alpha so they are mutually exclusive. Index: linux-2.5.60-uml/arch/alpha/kernel/smp.c =================================================================== RCS file: /build/cvsroot/linux-2.5.60/arch/alpha/kernel/smp.c,v retrieving revision 1.1.1.1 diff -u -r1.1.1.1 smp.c --- linux-2.5.60-uml/arch/alpha/kernel/smp.c 10 Feb 2003 22:14:47 -0000 1.1.1.1 +++ linux-2.5.60-uml/arch/alpha/kernel/smp.c 14 Feb 2003 11:49:53 -0000 @@ -668,38 +667,7 @@ }; static struct smp_call_struct *smp_call_function_data; - -/* Atomicly drop data into a shared pointer. The pointer is free if - it is initially locked. If retry, spin until free. */ - -static int -pointer_lock (void *lock, void *data, int retry) -{ - void *old, *tmp; - - mb(); - again: - /* Compare and swap with zero. */ - asm volatile ( - "1: ldq_l %0,%1\n" - " mov %3,%2\n" - " bne %0,2f\n" - " stq_c %2,%1\n" - " beq %2,1b\n" - "2:" - : "=&r"(old), "=m"(*(void **)lock), "=&r"(tmp) - : "r"(data) - : "memory"); - - if (old == 0) - return 0; - if (! retry) - return -EBUSY; - - while (*(void **)lock) - barrier(); - goto again; -} +static spinlock_t call_lock = SPIN_LOCK_UNLOCKED; void handle_ipi(struct pt_regs *regs) @@ -829,9 +797,8 @@ atomic_set(&data.unstarted_count, num_cpus_to_call); atomic_set(&data.unfinished_count, num_cpus_to_call); - /* Acquire the smp_call_function_data mutex. */ - if (pointer_lock(&smp_call_function_data, &data, retry)) - return -EBUSY; + spin_lock(&call_lock); + smp_call_function_data = &data; /* Send a message to the requested CPUs. */ send_ipi_message(to_whom, IPI_CALL_FUNC); @@ -865,7 +832,8 @@ /* We either got one or timed out -- clear the lock. */ mb(); - smp_call_function_data = 0; + smp_call_function_data = NULL; + spin_unlock(&call_lock); /* * If after both the initial and long timeout periods we still don't - 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/