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Re: [PATCH] MIPS: add smp_call_function_single()

To: Ralf Baechle <ralf@linux-mips.org>
Subject: Re: [PATCH] MIPS: add smp_call_function_single()
From: Stephane Eranian <eranian@hpl.hp.com>
Date: Fri, 27 Jul 2007 06:53:23 -0700
Address: HP Labs, 1U-17, 1501 Page Mill road, Palo Alto, CA 94304, USA.
Cc: linux-kernel@vger.kernel.org, mucci@cs.utk.edu, linux-mips@linux-mips.org, ak@suse.de, akpm@linux-foundation.org
E-mail: eranian@hpl.hp.com
In-reply-to: <20070727125533.GD5118@linux-mips.org>
Organisation: HP Labs Palo Alto
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20070727124451.GC9828@frankl.hpl.hp.com> <20070727125533.GD5118@linux-mips.org>
Reply-to: eranian@hpl.hp.com
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.4.1i
Ralf,

Here is take 2.

[MIPS] add smp_call_function_single (take 2)

signed-off-by: Stephane Eranian <eranian@hpl.hp.com>
signed-off-by: Phil Mucci <mucci@cs.utk.edu>

diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
index be7362b..d47234c 100644
--- a/arch/mips/kernel/smp.c
+++ b/arch/mips/kernel/smp.c
@@ -193,6 +193,53 @@ void smp_call_function_interrupt(void)
        }
 }
 
+int smp_call_function_single(int cpu, void (*func) (void *info), void *info, 
int retry,
+                            int wait)
+{
+       struct call_data_struct data;
+       int me = smp_processor_id();
+
+       /*
+        * Can die spectacularly if this CPU isn't yet marked online
+        */
+       BUG_ON(!cpu_online(me));
+       if (cpu == me) {
+               WARN_ON(1);
+               return -EBUSY;
+       }
+
+       /* Can deadlock when called with interrupts disabled */
+       WARN_ON(irqs_disabled());
+
+       data.func = func;
+       data.info = info;
+       atomic_set(&data.started, 0);
+       data.wait = wait;
+       if (wait)
+               atomic_set(&data.finished, 0);
+
+       spin_lock(&smp_call_lock);
+       call_data = &data;
+       mb();
+
+       /* Send a message to the other CPU */
+       core_send_ipi(cpu, SMP_CALL_FUNCTION);
+
+       /* Wait for response */
+       /* FIXME: lock-up detection, backtrace on lock-up */
+       while (atomic_read(&data.started) != 1)
+               barrier();
+
+       if (wait)
+               while (atomic_read(&data.finished) != 1)
+                       barrier();
+       call_data = NULL;
+       spin_unlock(&smp_call_lock);
+
+       return 0;
+}
+EXPORT_SYMBOL(smp_call_function_single);
+
 static void stop_this_cpu(void *dummy)
 {
        /*

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