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SubjectRe: [PATCH][2.5][7/14] smp_call_function_on_cpu - PPC64
One liner to fix num_cpus == 0 on SMP kernel w/ UP box

Index: linux-2.5.60/arch/ppc64/kernel/smp.c
===================================================================
RCS file: /build/cvsroot/linux-2.5.60/arch/ppc64/kernel/smp.c,v
retrieving revision 1.1.1.1
diff -u -r1.1.1.1 smp.c
--- linux-2.5.60/arch/ppc64/kernel/smp.c 10 Feb 2003 22:15:14 -0000 1.1.1.1
+++ linux-2.5.60/arch/ppc64/kernel/smp.c 14 Feb 2003 12:23:03 -0000
@@ -452,29 +452,34 @@
#define SMP_CALL_TIMEOUT (1UL << (30 + 3))

/*
- * This function sends a 'generic call function' IPI to all other CPUs
- * in the system.
+ * smp_call_function_on_cpu - Runs func on all processors in the mask
*
- * [SUMMARY] Run a function on all other CPUs.
- * <func> The function to run. This must be fast and non-blocking.
- * <info> An arbitrary pointer to pass to the function.
- * <nonatomic> currently unused.
- * <wait> If true, wait (atomically) until function has completed on other CPUs.
- * [RETURNS] 0 on success, else a negative status code. Does not return until
- * remote CPUs are nearly ready to execute <<func>> or are or have executed.
+ * @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 ret = -1, cpus = num_online_cpus()-1;
+ int ret, cpu, i, num_cpus;
unsigned 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;
@@ -487,11 +492,18 @@
call_data = &data;
wmb();
/* Send a message to all other CPUs and wait for them to respond */
- smp_message_pass(MSG_ALL_BUT_SELF, PPC_MSG_CALL_FUNCTION, 0, 0);
+ if (mask == (cpu_online_map & ~(1UL << cpu))) {
+ smp_message_pass(MSG_ALL_BUT_SELF, PPC_MSG_CALL_FUNCTION, 0, 0);
+ } else {
+ for (i = 0; i < NR_CPUS; i++) {
+ if (cpu_online(i) && ((1UL << i) & mask))
+ smp_message_pass(i, PPC_MSG_CALL_FUNCTION, 0, 0);
+ }
+ }

/* Wait for response */
timeout = SMP_CALL_TIMEOUT;
- while (atomic_read(&data.started) != cpus) {
+ while (atomic_read(&data.started) != num_cpus) {
HMT_low();
if (--timeout == 0) {
#ifdef CONFIG_DEBUG_KERNEL
@@ -499,15 +511,16 @@
debugger(0);
#endif
printk("smp_call_function on cpu %d: other cpus not "
- "responding (%d)\n", smp_processor_id(),
+ "responding (%d)\n", cpu,
atomic_read(&data.started));
+ ret = -EIO;
goto out;
}
}

if (wait) {
timeout = SMP_CALL_TIMEOUT;
- while (atomic_read(&data.finished) != cpus) {
+ while (atomic_read(&data.finished) != num_cpus) {
HMT_low();
if (--timeout == 0) {
#ifdef CONFIG_DEBUG_KERNEL
@@ -516,20 +529,27 @@
#endif
printk("smp_call_function on cpu %d: other "
"cpus not finishing (%d/%d)\n",
- smp_processor_id(),
+ cpu,
atomic_read(&data.finished),
atomic_read(&data.started));
+ ret = -EIO;
goto out;
}
}
}

ret = 0;
-
out:
HMT_medium();
spin_unlock(&call_lock);
+ put_cpu_no_resched();
return ret;
+}
+
+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_interrupt(void)
-
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