SPARC: SMP: Remove call to ipi_call_lock_irq()/ipi_call_unlock_irq()
Yong Zhang [Tue, 29 May 2012 08:27:33 +0000 (16:27 +0800)]
ipi_call_lock/unlock() lock resp. unlock call_function.lock. This lock
protects only the call_function data structure itself, but it's
completely unrelated to cpu_online_mask. The mask to which the IPIs
are sent is calculated before call_function.lock is taken in
smp_call_function_many(), so the locking around set_cpu_online() is
pointless and can be removed.

Delay irq enable to after set_cpu_online().

[ tglx: Massaged changelog ]

Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Cc: ralf@linux-mips.org
Cc: sshtylyov@mvista.com
Cc: david.daney@cavium.com
Cc: nikunj@linux.vnet.ibm.com
Cc: paulmck@linux.vnet.ibm.com
Cc: axboe@kernel.dk
Cc: peterz@infradead.org
Cc: sparclinux@vger.kernel.org
Link: http://lkml.kernel.org/r/20120529082732.GA4250@zhy
Acked-by: "David S. Miller" <davem@davemloft.net>
Acked-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/sparc/kernel/smp_64.c

index f591598..781bcb1 100644 (file)
@@ -103,8 +103,6 @@ void __cpuinit smp_callin(void)
        if (cheetah_pcache_forced_on)
                cheetah_enable_pcache();
 
-       local_irq_enable();
-
        callin_flag = 1;
        __asm__ __volatile__("membar #Sync\n\t"
                             "flush  %%g6" : : : "memory");
@@ -124,9 +122,8 @@ void __cpuinit smp_callin(void)
        while (!cpumask_test_cpu(cpuid, &smp_commenced_mask))
                rmb();
 
-       ipi_call_lock_irq();
        set_cpu_online(cpuid, true);
-       ipi_call_unlock_irq();
+       local_irq_enable();
 
        /* idle thread is expected to have preempt disabled */
        preempt_disable();
@@ -1308,9 +1305,7 @@ int __cpu_disable(void)
        mdelay(1);
        local_irq_disable();
 
-       ipi_call_lock();
        set_cpu_online(cpu, false);
-       ipi_call_unlock();
 
        cpu_map_rebuild();