Re: [PATCH][2.5][10/14] smp_call_function_on_cpu - sparc64

From: Zwane Mwaikambo (zwane@holomorphy.com)
Date: Fri Feb 14 2003 - 07:52:42 EST


One liner to fix num_cpus == 0 on SMP kernel w/ UP box

Index: linux-2.5.60/arch/sparc64/kernel/smp.c
===================================================================
RCS file: /build/cvsroot/linux-2.5.60/arch/sparc64/kernel/smp.c,v
retrieving revision 1.1.1.1
diff -u -r1.1.1.1 smp.c
--- linux-2.5.60/arch/sparc64/kernel/smp.c 10 Feb 2003 22:14:11 -0000 1.1.1.1
+++ linux-2.5.60/arch/sparc64/kernel/smp.c 14 Feb 2003 12:23:46 -0000
@@ -487,18 +487,34 @@
 extern unsigned long xcall_call_function;
 
 /*
+ * smp_call_function_on_cpu - Runs func on all processors in the mask
+ *
+ * @func: The function to run. This must be fast and non-blocking.
+ * @info: An arbitrary pointer to pass to the function.
+ * @wait: If true, wait (atomically) until function has completed on other CPUs.
+ * @mask The bitmask of CPUs to call the function
+ *
+ * Returns 0 on success, else a negative status code. Does not return until
+ * remote CPUs are nearly ready to execute func or have executed it.
+ *
  * You must not call this function with disabled interrupts or from a
  * hardware interrupt handler or from a bottom half handler.
  */
-int smp_call_function(void (*func)(void *info), void *info,
- int nonatomic, int wait)
+
+int smp_call_function_on_cpu(void (*func)(void *info), void *info,
+ int wait, unsigned long mask)
 {
         struct call_data_struct data;
- int cpus = num_online_cpus() - 1;
+ int num_cpus, cpu;
         long timeout;
 
- if (!cpus)
+ cpu = get_cpu();
+ mask &= ~(1UL << cpu);
+ num_cpus = hweight64(mask);
+ if (num_cpus == 0) {
+ put_cpu_no_resched();
                 return 0;
+ }
 
         data.func = func;
         data.info = info;
@@ -506,32 +522,34 @@
         data.wait = wait;
 
         spin_lock(&call_lock);
-
         call_data = &data;
-
- smp_cross_call(&xcall_call_function, 0, 0, 0);
+ smp_cross_call_masked(&xcall_call_function, 0, 0, 0, mask);
 
         /*
- * Wait for other cpus to complete function or at
+ * Wait for target cpus to complete function or at
          * least snap the call data.
          */
         timeout = 1000000;
- while (atomic_read(&data.finished) != cpus) {
- if (--timeout <= 0)
- goto out_timeout;
+ while (atomic_read(&data.finished) != num_cpus) {
+ if (--timeout <= 0) {
+ printk("XCALL: Remote cpus not responding, ncpus=%d finished=%d\n",
+ num_cpus, atomic_read(&data.finished));
+ goto out;
+ }
                 barrier();
                 udelay(1);
         }
 
+out:
         spin_unlock(&call_lock);
-
+ put_cpu_no_resched();
         return 0;
+}
 
-out_timeout:
- spin_unlock(&call_lock);
- printk("XCALL: Remote cpus not responding, ncpus=%d finished=%d\n",
- num_online_cpus() - 1, atomic_read(&data.finished));
- return 0;
+int smp_call_function (void (*func) (void *info), void *info, int nonatomic,
+ int wait)
+{
+ return smp_call_function_on_cpu(func, info, wait, cpu_online_map);
 }
 
 void smp_call_function_client(int irq, struct pt_regs *regs)
-
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