Re: [PATCH]Timer list init is done AFTER use

[Andrew Morton]

george anzinger wrote:
> 
> ...
> I am not sure.  The first question is when does the online
> bit get set for cpu 0.  The next is that it does inhibit a
> rather large block of printks.  Is this ok?
> 

The boot cpu is set online extremely late.  Strangely late.  Why
is this?

How about something like the below?  We mark the boot cpu 
online in generic code as soon as it has initialised its per-cpu
storage (seems appropriate?)

This will then allow that cpu to actually start calling into console
drivers, if they have been registered.  If those drivers do a mod_timer()
(as the vga console does) then that will work OK.

Secondary CPUs also are not marked online until their per-cpu storage is
initialised, and their notifiers have been called.

If a non-online cpu calls printk, its output will be buffered.  It will
be displayed by the next call to printk by an online CPU.

(The patch needs set_cpu_online()/set_cpu_possible() implementations
done for the other architectures)

 arch/i386/kernel/smpboot.c |    5 -----
 include/asm-i386/smp.h     |   29 +++++++++++++++++++++++------
 include/linux/smp.h        |    7 ++++++-
 init/main.c                |    8 ++++++++
 kernel/printk.c            |    6 +++++-
 5 files changed, 42 insertions(+), 13 deletions(-)

--- 25/kernel/printk.c~ga	Sat Dec 21 23:27:08 2002
+++ 25-akpm/kernel/printk.c	Sat Dec 21 23:27:08 2002
@@ -43,7 +43,11 @@
 #define LOG_BUF_MASK	(LOG_BUF_LEN-1)
 
 #ifndef arch_consoles_callable
-#define arch_consoles_callable() (1)
+/*
+ * Some console drivers may assume that per-cpu resources have been allocated.
+ * So don't allow them to be called by this CPU until it is officially up.
+ */
+#define arch_consoles_callable() cpu_online(smp_processor_id())
 #endif
 
 /* printk's without a loglevel use this.. */
--- 25/init/main.c~ga	Sat Dec 21 23:48:03 2002
+++ 25-akpm/init/main.c	Sat Dec 21 23:55:00 2002
@@ -361,6 +361,14 @@ asmlinkage void __init start_kernel(void
 	printk(linux_banner);
 	setup_arch(&command_line);
 	setup_per_cpu_areas();
+
+	/*
+	 * Once the boot CPU's per-cpu memory is set up it may be considered
+	 * online.  This is mainly to turn on printk output.
+	 */
+	set_cpu_online(smp_processor_id());
+	set_cpu_possible(smp_processor_id());
+
 	build_all_zonelists();
 	page_alloc_init();
 	printk("Kernel command line: %s\n", saved_command_line);
--- 25/include/asm-i386/smp.h~ga	Sat Dec 21 23:49:43 2002
+++ 25-akpm/include/asm-i386/smp.h	Sat Dec 21 23:54:16 2002
@@ -80,15 +80,32 @@ extern volatile int logical_apicid_to_cp
 
 extern volatile unsigned long cpu_callout_map;
 
-#define cpu_possible(cpu) (cpu_callout_map & (1<<(cpu)))
-#define cpu_online(cpu) (cpu_online_map & (1<<(cpu)))
+static inline int cpu_possible(int cpu)
+{
+	return cpu_callout_map & (1 << cpu);
+}
+
+static inline void set_cpu_possible(int cpu)
+{
+	cpu_callout_map |= (1 << cpu);
+}
+
+static inline int cpu_online(int cpu)
+{
+	return cpu_online_map & (1 << cpu);
+}
+
+static inline void set_cpu_online(int cpu)
+{
+	cpu_online_map |= (1 << cpu);
+}
 
-extern inline unsigned int num_online_cpus(void)
+static inline unsigned int num_online_cpus(void)
 {
 	return hweight32(cpu_online_map);
 }
 
-extern inline int any_online_cpu(unsigned int mask)
+static inline int any_online_cpu(unsigned int mask)
 {
 	if (mask & cpu_online_map)
 		return __ffs(mask & cpu_online_map);
@@ -96,13 +113,13 @@ extern inline int any_online_cpu(unsigne
 	return -1;
 }
 
-static __inline int hard_smp_processor_id(void)
+static inline int hard_smp_processor_id(void)
 {
 	/* we don't want to mark this access volatile - bad code generation */
 	return GET_APIC_ID(*(unsigned long *)(APIC_BASE+APIC_ID));
 }
 
-static __inline int logical_smp_processor_id(void)
+static inline int logical_smp_processor_id(void)
 {
 	/* we don't want to mark this access volatile - bad code generation */
 	return GET_APIC_LOGICAL_ID(*(unsigned long *)(APIC_BASE+APIC_LDR));
--- 25/arch/i386/kernel/smpboot.c~ga	Sat Dec 21 23:52:51 2002
+++ 25-akpm/arch/i386/kernel/smpboot.c	Sat Dec 21 23:54:43 2002
@@ -992,11 +992,6 @@ static void __init smp_boot_cpus(unsigne
 	printk("CPU%d: ", 0);
 	print_cpu_info(&cpu_data[0]);
 
-	/*
-	 * We have the boot CPU online for sure.
-	 */
-	set_bit(0, &cpu_online_map);
-	set_bit(0, &cpu_callout_map);
 	boot_cpu_logical_apicid = logical_smp_processor_id();
 	map_cpu_to_boot_apicid(0, boot_cpu_apicid);
 
--- 25/include/linux/smp.h~ga	Sun Dec 22 00:29:05 2002
+++ 25-akpm/include/linux/smp.h	Sun Dec 22 00:30:15 2002
@@ -94,7 +94,12 @@ static inline void smp_send_reschedule_a
 #define cpu_online(cpu)				({ BUG_ON((cpu) != 0); 1; })
 #define num_online_cpus()			1
 #define num_booting_cpus()			1
-#define cpu_possible(cpu)				({ BUG_ON((cpu) != 0); 1; })
+#define cpu_possible(cpu)			({ BUG_ON((cpu) != 0); 1; })
+static inline void set_cpu_online(int cpu)
+{}
+static inline void set_cpu_possible(int cpu)
+{}
+
 
 struct notifier_block;
 

_